Drought Tolerant Plantings: A Review of Riverplace and South Waterfront, Summer ‘12 (updated Aug. ’14)

 

Riverplace Esplanade Bank looking south along the Marina toward the Marquam Bridge

Riverplace Esplanade Bank looking south along the Marina toward the Marquam Bridge.  My last big xeriscape experiment.

The following is an evaluation I initially did while still working for Portland Parks and Recreation.  I’ve edited it a bit and added a few things to make it more current.  I think it’s important for people to know what others are doing, what they’ve tried and what were the successes and failures.  While kind of long it is still a brief look at the conditions on a few sites that were under my care and my observations concerning their performance.  As Downtown area Parks these landscapes are very accessible for those curious to see how these plants have done on the ground.  Now, most of you if your gardening is limited to your own backyards will never have to deal with landscapes so large, nor will your growing conditions, specifically your soil, be the same, I thought that it would be interesting to share this anyway, in addition to letting you know where you can come see how these plants can look in a landscape.  All were planted small as they tend to better adapt to their sites when small, but some are beginning to mature and show what they can do.  Anyway, I view our Parks as a public asset.  There are many valuable and important plantings around us, that the public is largely unaware of.  Part of my role here is to change this situation through promotions like this and by continuing to work with horticulturist to create some kind of database of public and private plantings that is accessible for viewing by the general public.

I started changing plantings out on these two sites in an attempt to move away from doing any irrigation. Irrigation was leading to an ever heavier weed load due in part, more than likely, to the loss of effective herbicides and staff spread more thinly. Both of these sites border the Willamette and long ago were filled with some of the regions most noxious and invasive weeds. The lower portion has ‘always’ been armored with rip-rap. These are created sites, built up to help contain the River, over the decades with whatever soils and fill were available. Some of this area was used for early production of electricity. They have compacted mineral soils, with a relatively steep slope compared to typical riverbank. Riverplace is full of fist size and smaller rock embedded in high clay content soil, making digging even more difficult. When dry both sites are very hard. I used a pick-axe or rock bar as necessary to break the soil for root penetration. South Waterfront Park when built in ’98-’99 was capped with a foot and a half of sandy loam, supposedly, bladed and compacted to the point when it was planted using augers, the sides of the holes were like brick. Needless to say this makes the root zone shallow and inhospitable. Most of this area receives full sun up to at least mid-afternoon. This area is hot and dry despite its proximity to the river.

For over 20 years the Riverplace bank was dominated by mature English Ivy. It had scattered clumps of Red Twig Dogwood and a few small groves of Bald Cypress. The irrigation system was not operational. The Ivy was sprayed and several weeks later large track hoes raked the top and root growth off of the site prior to planting. The area is over 800’ long so this took many 12 yd. dump truck loads. The thin organic top layer was hauled off with it. No topsoil was replaced. No amendments were added.

It was then planted in large sweeps, most stretching from the top of the bank down to the rip-rap level. These were mostly pure single species stands that were very quickly inundated with weeds. No tree layer was planted. Shrubs, Ceanothus ‘Vandenberg’ were planted in clumps 30”o.c. which caused the plants to grow tall and weak resulting in them being broken down by heavy snows a few years later resulting in large open ‘dead’ areas within the plantings. (This process continues to this day, Summer ’14, though now the remaining gawky plants are gradually leveraging themselves out of the ground.)

I began doing supplemental plantings trying to preserve much of the view while adding a more diverse shrub ‘layer’ and trees that would be both drought tolerant and competitive with the weeds that had been moving in from the river. Plants were also added to the ground herbaceous level to diversify the heavy reliance on single species planting of bunch grasses. All of these have been moderately successful to this point.

All of the plantings I’ll discuss were done in the falls of 2009, ‘10 and ‘11 early enough to get their roots established. (I also added a smaller number fall ’12.) None have received any auxiliary irrigation. The last two springs, ’11 and ‘12 were cooler and wetter than normal (’13 was warmer with a much drier June) and have run through June, probably improving the plantings chances for survival. The summer of ’12 was nearly a record dry summer stressing some plants that had done well through the previous summer.

 

Reference is made in my evaluations below to clumps of Bald Cypress, Taxodium distichum. These were planted when Riverplace was first constructed, so around ’85. They have done okay even though they prefer wet conditions. (There has been no regular irrigation on site for many years other than for a couple of years after the replanting project in ’06???) A couple of these have proven to be a little brittle and have suffered some breakage over the years. Many of the neighbors dislike them because they block the views from their condos and have repeatedly argued to have them removed. They don’t want any trees on site. The Oaks I have planted will be an issue for them as they grow up, but more canopy will be advantageous over time regarding site maintenance and limiting weed growth.

 

 

The following observations were made in Nov. of ’12. (update Aug. ’14)

 

Arctostaphylos Species and Varieties (The numbered sections referred to below are the grassy swathes between the Bald Cypress and Ceanothus plantings along the Riverplace Esplanade. They start from the north end.) This is a drought tolerant genus of 60 species native mostly to the west coast of North America ranging from central and northern Mexico to southern British Columbia. Three species, the Bearberries, A. alpina, A. rubra and A. uva-ursi are circumpolar and can be found in arctic and sub-arctic regions. Most are chaparral dwellers preferring winter wet and summer dry conditions. All but one is evergreen. In general, they are intolerant of overhead irrigation in the warm summer months. Irrigation can lead to fatal fungal diseases. As a group they prefer well-drained soils. Xera Plants among a few others have been testing performance in the NW and offer a selection of dependable performers given that they are well sited and conditions are maintained to their liking. Cistus Design Nursery also is a good source.

Arctostaphylos bakeri ‘Louis Edmonds’ was planted in the fall of ’10 on the bank in section 3. This is the area between the groupings of Bald Cypress that centers on the Bean and Tree coffee shop. Most of these have survived and show at least moderate growth. One shows considerable stress.

Arctostaphylos canescens ‘Sonomaensis’ was planted in the fall of ’10 and ’11 in the little triangles south of the floating restaurant in South Waterfront Park just inside the Esplanade next to the Garden. The soils in these two areas were amended with a couple inches of pumice. These have grown slowly but look healthy.

Arctostaphylos densiflora ‘Harmony’ was planted in the fall of ’10 on the bank in section 4. This is the area between the groupings of Bald Cypress that overlaps the north end of The Harborside restaurant. These have done okay though they were showing stress in early Sept. ’12 and three look like they’ve been broken by Park abusers. (Fireworks observers spread blankets on the bank and have crushed many plants some that have not recovered.) In November two of these, the smashed ones, were dead.

Arctostaphylos densiflora ‘Howard McMinn’ was planted in the fall of ’07 on the bank just north of section 4 above some Ceanothus ‘Vandenburg’. It did receive some summer water its first two years, but none since, and has grown slowly, as is typical, over the period. The plants are healthy. I also planted these in the steep west facing strip next to the parking lot in lower Duniway Park about 15 years ago. These later were watered the first summer with a soaker hose one day a week. They have grown slowly but steadily.

Arctostaphylos pajaroense ‘Warren Roberts’ was planted in the fall of ’10 in section 1. It is a medium grower I’m more familiar with and has done okay but is now showing some stress in Sept. ’12. As October wore on, the foliage reddened and dulled, as drought further stressed them. In November, with the onset of rains the color and foliage has improved. At South Waterfront where it was planted with a more northerly aspect facing the south end of the Marina, it shows less stress. Another was planted at Waterfront Park’s Mast Bed in ’08 and shows excellent vigor (These beds have deeper better drained soil).

Arctostaphylos rudis I’ve planted this fall,’12, at South Waterfront at the top of Bank between the Restaurant Ramp and the North Overlook with the Ceanothus ‘Skylark’ and C.‘Centennial’.  Thus far it has performed well, exhibiting good color and vigor.

Arctostaphylos x ‘Austin Griffiths’ has done well immediately wherever I have planted it which includes at Riverplace in section 2 adjacent to The Little River Café, in a band south of the garbage can enclosure at South Waterfront and a single plant at the Waterfront Park Mast Bed. These plantings were made in ’10. This is the largest grower I have tried, to 10’+, and it is growing with vigor. The least vigorous is the section 2 Riverplace planting, probably 30% shorter. One plant, at the north end of this section, the most exposed, is dead. In fall ’12 I’ve planted a few below the viewpoint at 5 Flags. This section is much steeper and has not had all of the Ivy removed yet.

Arctostaphylos x ‘Pacific Mist’ was planted in fall ’10 at the top of the bank at South Waterfront in front of the transformers, above the Marina ramp, adjacent to the Newport Grill’s garbage enclosure and a small narrow triangle island in the esplanade just south. It is more of a groundcover and is said to be somewhat tolerant of occasional irrigation. The garbage enclosure and the triangle plantings have gotten no water and have done well though the Zauschneria and Penstemon plantings are crowding. The plantings at the top of the ramp are suffering from the competition with their neighbors, specifically an established planting of the now out of place Japanese Maples which are very thirsty and Penstemons around the electric transformers to the other side. These two latter plantings have required supplemental irrigation due to the root competition so I don’t know how successful they will be. The others should be fine. One of the plants in the triangle lost over 1/3 of its growth when someone kicked it.

Arctostaphylos x ‘John Dourley’ I’ll be planting at 5 Flags this fall ’12. (These have struggled. Several of died, the others have died to their base later coming back slowly. This area was beefed up with a few Arctostaphylos x ‘Sunset’ in the fall of ’13.)

Arctostaphylos x ‘Sunset’ was planted in the fall of ‘ll at the top of the bank above the floating restaurant (Newport Grill) around the natural gas regulator. These look healthy and are showing good vigor. They have received no supplemental water this summer. A planting was made further south between the south overlook and the south ramp the year before. These are struggling. This area is different in that turf irrigation sheets off into the area from the lawn to the west. The area supports an increasing colony of Horsetail. Other drought type plantings are struggling in the same area including Pacific Madrone and Aesculus californica. (This area was severely set back by a Northwest Natural Gas project in fall/winter ’13. The area was within their right-of-way and they dug two large holes with equipment directly and indirectly killing many plants in the area. The same project removed more than 10 Red Alder trees, a large swath of Clethra alnifolia ‘Hummingbird’, Salal and others from adjacent irrigated, more interior beds in the Park. Renovation is still forthcoming.)

            Arctostaphylos viscida ‘Sweet Adinah’ was planted in ’11. I just had a few and planted them in the dead centers of the Ceanothus ‘Vandenberg’ plantings. These sites were very exposed and had a heavy layer of accumulated Ceanothus leaves. In section 2 it has done okay, not showing a lot of vigor. In section 4 they are dead though some of these areas have been used by the homeless and were physically ‘abused’. I don’t think this was a fair test. This plant is less available. (A few were replanted in fall ’12, including one between the Marina and Restaurant ramps, which died as of this summer ‘14.)

 

Ceanothus Species and Varieties (Of all of the plants discussed here I am most familiar with these over my gardening career as I started growing them over 20 years ago.) Ceanothus have a reputation for being short lived here. If the planter takes into consideration their preferred conditions they can be much more ‘durable’. Provide them with full sun. They need no summer water here. Prefer good drainage. Commonly grow in nutrient poor soils with low organic content. These were all planted in smaller sizes in the fall with enough time for their roots to extend into surrounding soil before our summer drought period began. In one case, at the Battleship Oregon Mast, sand was added along with pumice to the soil, a few were amended with pumice alone at South Waterfront next to the Garden, these were on essentially flat grades, while the remainder were unamended. These last plantings, where the bulk of the plantings were made, are on the river bank with significant slope which speeds surface runoff. Organic mulch should be avoided. If mulch is desired use ¼-12 gravel. These planting instructions hold for most of the plants discussed in this review.

 

Ceanothus cuneatusBlue Sierra’ is brand new to me. I’ve just planted it in sections 2 and 3. (As of summer ’14 these, three individual plants, are alive and doing well.)

Ceanothus gloriosus exaltatus ‘Emily Brown’ I first planted this in about ’06 at Waterfront’s Mast. The plant proved way more vigorous than I expected and I removed it as it overwhelmed its neighbors and grew out of scale (It is a relatively low dense plant for a Ceanothus). I planted it at Riverplace in ’10. In section 4 it is proving slow but steady and has been able to compete with the various grasses that crowd it including Festuca rubra commutata and one of the nasty annual Bromes. It has been best performing t the top of the bank between the marina and restaurant ramps.

Ceanothus impressus ‘Vandenberg’ was part of the original planting in’05. This has proven to be a tough performer for me over the years. I first started growing it over 12 years ago at home where it grew to 7’ in my parking strip. It tolerates minimal irrigation. In full sun it is a dense stout shrub. Planted on 30” centers, as it was at Riverplace, it grew quickly stretching and flopping over leaving large, ugly, dead centers, sometimes uprooting itself on the compacted soil.

Ceanothus (thrysiflorus x dellianus?)‘Tuxedo’ I planted one in ’10 as an experiment above the transformers at the south end of Riverplace. Because of the way the irrigation is piped, I have had to water this area to supplement another bed that was showing stress. C. ‘Tuxedo’ is a hybrid of our west coast native C. thyrsiflorus and C. dellianus, an East Coast species tolerant of summer wet (a sport of Ceanothus Autumnal Blue). The first summer this looked wonderful. This year, by late September, it began to defoliate though the cambium still looks good. By summer, ’13, I thought it dead so I cut it to the ground. Walking by it in July ’14, I saw that it had resprouted. Who knows?

Ceanothus thyrsiflorus ‘Eldorado’ I first grew this variegated cultivar at home in ‘06 on a south facing wall. It’s a yellow leaf margins that really sets off its flowers. So I tried it in the Parks. I planted in the ‘Biotope’ soil at Tanner Springs where it did poorly, many plants have struggled and died in this coarse, mineral, excuse for soil. At Riverplace in section 2 it is a weak performer while in section 4 it is double the size at around 5’. Both plants are just north of Bald Cypress plantings and receive some protection from the most intense sun. This one seems to require deeper soil. There is another one, planted in ’09, that is struggling at the base of the North Overlook at South Waterfront its leaves are quite stunted.

Ceanothus thyrsiflorus ‘Repens’ I will be planting at 5 Flags this fall, ’12. (This planting failed. The pots were small, so the plants had too little energy in reserve to get their roots established on this difficult site.)

Ceanothus thyrsiflorus ‘Skylark’ is one of my favorite as it is more compact than the most commonly found C. Victoria with very nice glossy foliage. I was growing this one at home as early as ‘97. It has been by the Park sign at Tanner Springs in the upland portion since ’09 and has done well. There is one near the garbage enclosure above the Riverplace Marina, planted in ’09, that shows good vigor. Another planting was done at South Waterfront on the bank immediately below and north of the North Overlook.   These have been slow with stunted growth. Also in this area is Snowberry that has never done very well. I have added one to the 5 Flags project in ’12 and a loose sweep of them near the top of the bank in South Waterfront north of the earlier planting.

Ceanothus thyrsiflorus ‘OregonMist’ is a tall form, to 15’, I’ve planted in ’12, one above the ramp to the north of the breakwater and a few others in open areas near the still declining Ceanothus ‘Vandenberg’ along Riverplace. Another stands by itself north of the North Overlook at South Waterfront just south of where the Fremontodendron is planted.

Ceanothus foliosus x griseus ‘Centennial’ I’ve just planted at South Waterfront at the top of the bank in front of the new C. ‘Skylark’ plantings, fall ’12. These are on flat ground adjacent to the Esplanade have been stomped by unobservant people and/or dog walkers who ‘use’ the area.  They are gone.

 

West Coast (+) Oaks These have been planted at South Waterfront and Riverplace to eventually replace the original plantings of Red Alder which I have been removing gradually to give more room to the Oaks (primarily Q. garryana) as the grow. Other Oaks were planted to interrupt sun, thus reducing weed growth, and framing views across the river. The Alders have been managed as place-holders.

 

Quercus chrysolepsis were planted in ’09, out of 5gal pots, in sections 3 and 4 near the C. ‘Vandenberg’. These have done well being both bushy and putting on good vertical growth. Next year (’13) they should be above the Ceanothus. The low bushy growth will be left on to help keep the Beaver away from the trunk.

 

Quercus garryana has been planted gradually since ‘02 at South Waterfront. They were planted from deep pots and have been slow, as is typical and to be expected. The oldest and most vigorous, planted just toward the River from the Garbage Enclosure was about 2” caliper when Beaver cut it down and then chewed all of the sprouts off in summer, ‘ll. It has come back weakly. I’ve been making room as needed for some of the others by removing Alders.

 

Quercus hypoleucoides, the Mexican Silver Oak, has been proven around town as a good xeric street tree. I planted 3, in 5gal pots, in ’09 at South Waterfront above the Riverplace Marina. The one closest to the restaurant ramp has shown excellent vigor the other two have been significantly slower. All three were planted in the same soil conditions where the original soil covered with mature Ivy, was peeled off and replaced with sandy/loam from the same source used throughout South Waterfront. There is a Garry Oak growing strongly in this same area. The Calmagrostis planted here grows thin and weakly due to lack of irrigation.

 

Quercus kellogii was planted fall ’11 down near the Marquam Bridge. They have shown good growth since. This site is somewhat shaded by the Bridge, though it receives unobstructed rainfall. 4gal pots were planted.

 

Quercus suber, while not a West Coast Oak, it is a Mediterranean, I’m including it here. I planted 3 in ’11 in the same area as the Q. Kellogii and all have established without irrigation. 4gal pots were planted.

 

Quercus wisleznii was planted in ’09 at the north end of Riverplace in section 1. These showed good vigor, but were cut to the ground by Beaver in the summer of ’10. They have recovered strongly growing very bushy. I planted a few more on the bank at South Waterfront south of the North overlook. These looked good in November without putting on much new growth. (All are doing well as of Aug. ’14.)

 

 

Other Californians

 

Aesculus californica I planted one in the south east corner of the meadow at Tanner Springs in fall. It receives no irrigation. For some reason it has been stomped, smashed to the ground two years running, yet has come back. I also planted three at the south end of South Waterfront on the bank south of the South Overlook and north of the South Ramp. These, like several of the other drought tolerant plantings have grown weakly. Again, this is where irrigation sheets off from the adjacent turf area to the west and where Horsetail has been colonizing.

 

Calycanthus occidentalis I have planted three of these in South Waterfront, two in the shade of the remaining Red Alders north of the North overlook and one across the Esplanade with the Germander in the large triangle bed. The three look healthy and are growing slowly. They started blooming in summer of ’12.

 

Carpenteria californica I first planted this around ‘02 at home. It has grown strongly with late afternoon shade and minimal irrigation. I planted it at Ira Keller, down in the ‘pit’ in fall ’10 where it has grown well and begun blooming in similar conditions. I also planted these fall ’09 at Riverplace on the north side of several of the Bald Cypress clumps where they would get some protection from the hottest sun and late afternoon shade from the buildings. At the top of section 4 it is growing with some vigor. None have bloomed yet. In section 3 it is being engulfed by a volunteer Spiarea douglasii. The one in section 2 is okay, but weaker. There is another one next to the restaurant’s gas meter and another where the floating ramp takes off to the Newport Grill. Both of these are okay with good color while a little slow.

 

Cercis occidentalis I planted one of these just north of South Waterfront’s South and North Overlooks and another one down-slope from Riverplace’s electrical transformers. These were planted in fall ’10 and are established though none are thriving. They have grown weakly, defoliate early with very little bloom. Disappointing. At Riverplace section 1 and 2 both defoliated in August. Cambial tissue appears dead. Waiting to see if these come back from the base. These appear to need a more sheltered site, from the sun, and/or deeper soils. The Riverplace plantings are dead and gone by summer ’13.

 

Fremontedendron ‘San Gabriel’ I have not tried this yet but Stephan Bump planted one a few years ago in Washington Park at the front circle next to the ‘City Center’ sign at the base of a mature Doug Fir. It receives regular summer water, something you would normally think would cause its death, but apparently the Fir sucks away the extra moisture and the wet foliage does not lead to any foliar diseases. It blooms well for weeks. Stephan has given me one to try. I planted it fall ‘12 just north of the North Overlook at South Waterfront halfway down the bank. Though stomped and partially uprooted by people pushing through the Spiraea it is still growing, Aug. ’14, all be it slowly.

 

 

Rhamnus californica I planted these in scattered places along Riverplace below or adjacent to the clumps of Bald Cypress, in the fall of ‘10. All are still alive, have not defoliated. All are still alive and are performing with variable vigor, as of Aug. ’14. They are in sections 4, 3 and 2.

 

Romneya coulterii These are always iffy. I planted my first at home in good soil around 20 years ago on a south facing steep bank. It grew vigorously and bloomed profusely. In fact, it was too vigorous and I could not contain it. I removed it. Though not as aggressive as running bamboos, they will move steadily if conditions are to their liking. This plant does not behave itself in the garden that is tended fussily. I planted two more at Duniway Park one in the narrow sloped parking lot strip, which is still there and the other at the north end of the track. The later died after struggling for a couple of years. The three I planted a Riverplace died out, though these were not very vigorous to begin with. I planted three at South Waterfront on the bank. One, planted in ’10, is still growing, though without a lot of vigor, near the gas meter above the Newport Grill restaurant. Another was planted next the restaurant’s garbage enclosure, got stomped, and has since died. The third is just south of the South Overlook, and is growing now with some vigor. It started blooming in the summer or ’12.

 

Northwest Native Woodies: Trees and Shrubs (Oaks Above)

 

Amelanchier alnifolia These were planted in fall ’09 at Tanner Springs in the Biotope within a couple of feet of the rills that run year round. A dwarf form these have down okay though lack the expected vigor (It should be noted that they are planted in the Biotope, a soil, consisting of sand to rock of something less than 1/8” grit size. The specs were quite specific and suppliers had trouble delivering it.) After the first summer, the irrigation was turned off ‘below’ the turf area.

 

Amelanchier x grandiflora ‘Autumn Brilliance’ I planted these in ’10 at Tanner springs, two in a bed in the upper lawn area, which is not irrigated separately, and two in the upper portion of the meadow on the western side. These had been left in their pots too long and have shown limited growth so far. The two in the meadow showed leaf stress by late summer. All four are in full sun that for a woodland edge tree may be too much. The meadow trees are still really struggling (Aug. ’14).

 

Arbutus menziesii I first started planting these at least 20 years ago at Kelley Point when I noticed them volunteering elsewhere in the Park. Most of them died, but some hung on. At first I planted them bare root and later tried them in deep pots. Now I plant them in deep pots, two in a spot narrowly separated. My failure rate is still probably in the 50% range. But this is an iconic tree of the Willamette Valley and so worth the effort. These are intolerant of summer irrigation. 15 to 20 years ago there was still a beautiful specimen growing in a small tr iangle in the roadway along Mock’s Crest, Willamette Blvd. The Maintenance Bureau added a sprinkler system and it was dead within a year. Historically these were common along the River along steep rocky, well-drained hillsides and cliffs, places like the slopes at nearby Elk Rock Garden. There is one I planted 15 years ago at Duniway Park’s parking lot along Barbur. There are much younger trees at Riverplace and South Waterfront on the bank planted after ’06. I have added three more to the south side of 5 Flags in fall ‘12 to balance the plantings on the north side. Several are growing vigorously on either side of the Marina ramp that I planted in fall ’10. I cannot over emphasize how important it is to not water these. Plant small in the fall and cross your fingers. Several have died at South Waterfront between the South Overlook and the Marquam Overlook, an area, again, that is regularly wet from the turf runoff across the Esplanade. There are still three here with variable vigor, one despite having its crown broken out by vandals is doing well.

 

 

Cornus stolonifera None of these were planted here. Some were here up higher on the bank maybe from the original early eighties planting. Others continue to volunteer in the rip-rap.

 

Garrya elliptical ‘James Roof’ I’m guessing here that I planted this in ’06, my records were incomplete, and moved it two years later to its present location at South Waterfront just north of the South Overlook. It has been slow but steady despite the move. It was flattened the year after I moved it by vandals. It is now growing strongly protected by a Red Alder with Penstemon ovatus and Sidalcea campestre beneath it. It is finally starting to bloom well as I get the growth redirected up.

 

Holodiscus discolor These were scattered along Riverplace in the open areas along the lower half of the bank in fall ’09. These have all survived. Only a few are growing with vigor, the others are okay.

 

Philadelphus lewisii These were scattered along Riverplace in the open areas along the lower half of the bank in fall ’09. Several of these died in the first year. None are growing with any vigor.

 

Populus trichotomum These have been attempting to establish all along the river in the rip-rap. I have periodically cut and squirt these for my entire time here.

 

Ribes sanguineum A few were planted within each of the Bald Cypress clumps in fall ’09 in 5gal pots. All have done well except one that was pulled out by an ACS crew member while ‘weeding’.

 

Salix spp. These have volunteered in the rip-rap and I have controlled them by either cutting and squirting or over-spraying the whole plant. There has been a high priority on the neighbors part to maintain views of the Marina so I chose to control these and leave the Red Twig Dogwoods.

 

Spiarea betulifolia These were planted in fall ’09 at Tanner Springs in the Biotope near the rills or edge of pond. One is planted in the meadow. All are alive but show less than great vigor.

 

Spiarea douglasii None were ever planted at Riverplace, but they are volunteering on the site, primarily in the rip-rap, though also high on the bank.

 

West Coast Herbaceous

 

Achillea millefolium I planted more than a hundred of these in ’08 at Riverplace from plugs. Many of these made it, but I suspect I lost a lot of these when spraying for weeds in the following years.

 

Asclepias speciosa None of these made it to the second year from their fall ’08 planting at Riverplace.

 

Geum macrophyllum I planted many of these from gauge pots under the Bald Cypress in fall ’08. These have been moving around since. Some were lost from weed spraying.

 

Iris douglasii I planted these in the fall of ’08 in loose clumps below the Bald Cypress at Riverplace where they could receive some protection from the hottest part of the day. Most of the clumps have increased with some vigor. Several clumps have been walked on repeatedly and lost. I have planted around a dozen Pacific Coast hybrid Iris cultivars downtown (I. douglasii is used in many of the named cultivars) and a couple of I. tenax selections that have done well with no or minimal irrigation. Because they do most of their growth in the fall to spring they do best when planted in the fall. They are intolerant of root disturbance during the summer. In general, if you are going to put these in blazing sun they’ll need some irrigation. If you are going to irrigate them regularly in a garden situation, good drainage is a necessity. It’s a balance.

 

Lupinus polyphyllus was planted in fall ’08 in a widely scattered pattern in the open areas at Riverplace. A disappointing number survived and have grown well. Several were broken down by Park abusers.

 

Penstemon heterophyllus ‘Margarita B.O.P.’ Is a very nice blue selection of this western native. There are others available. This is planted at Battleship Oregon’s Mast where it has increased. I also grow P. h. ‘Electric Blue’ at home on my south bank. These are all very similar.

 

Penstemon x mexicali ‘Sunburst Ruby’ Penstemon is a genus indigenous to North America, most of them found in the West. I’ve planted this one at the top of bank at Riverplace, some of which might have been sprayed out accidentally. Others have been walked on in their position close to the Esplanade itself. In South Waterfront’s triangle beds, at the top of bank and at the Battleship Oregon’s Mast, these have moved around freely. The soil is deeper at these sites. I have weeded some of these out. My one concern is where they have grown into Arctostaphylos x ‘Pacific Mist’. I’m not sure the little Manzanita can outgrow the Penstemon when its small.

 

Penstemon ovatus I started planting these around ‘01 at South Waterfront along the top of bank below and near the clumps of Red Alder. Where they have been left alone they have increased and bloomed well. The first several years these were irrigated, but have gone without the since ‘08. I planted these in loose groups under the Bald Cypress at Riverplace in the fall of ‘08. At Riverplace people wander on the bank with their dogs etc and in a few places these have disappeared.

 

Sidalcea campestre These were scattered across Riverplace in the open areas up and down the bank in the fall of ’08. Many of these have established and bloom well. These were also planted at Tanner Springs in the meadow where they are holding their own.

 

Zauscheria californica ‘Silver Select’ is a stalwart performer. I first planted this one in ’09 at Tanner Springs at the edge of the west wall in regular sandy/loam. In fall ’10 I planted it in South Waterfront in both triangles in sandy/loam with pumice. It shows better vigor here growing to 24” blooming from mid-summer through November. It has begun moving around some near concrete edges. I don’t consider it a problem. In ‘ll I added it to the bed at top of the bank between the Marina Ramp and the Restaurant Ramp. In ’12 I added next to the Esplanade between the restaurant ramp and the North Overlook. The later did well through ’13 but took winter ’14 poorly and are struggling or dead. This last area has the worst soil conditions for them with little surface drainage, with a shallow ‘topsoil’ over a compacted layer due to earlier construction.

 

Zauschneria septentrionalis ‘Mattole Select’ I started growing this one at home around ‘05. More compact, with broader leaves, this is supposed to be the most tolerant of our winter wet. Did not make it in to South Waterfront bank plantings as plants became available later in the year than I was willing to plant them.

 

 

Mediterraneans and Other Woody Trials: Cistus, etc.

 

Arbutus x ‘Marina’ There are also a couple of these the bank at South Waterfront, one 50’ or so south of the North Overlook and the other just south of the South Overloo. While they establish and grow more quickly than our native Madrone they aren’t as cold tolerant. Both survivors exhibit a shrubby habit as they have been frozen back but have since recovered with vigor.

 

Arbutus arizonica I’ve experimented with four of these, fall ’12, at South Waterfront planting 3” deep tree pots, one up slope from the marina’s garbage enclosure, a second 50’ or so west behind the sweep of Spiraea, a third just north of the North Overlook below the Red Alders and a fourth above the north Ramp just north of the large clump of Red Alder. These are all still alive, showing little top growth while I’m hoping they are establishing their root systems. Time will tell.

 

Brachyglottis monroi was planted at the Battleship Oregon Mast in fall ’11. It was growing well before vandals smashed it flat splitting the crown. I grew it for 3 or 4 years on my south bank at home before we remodeled in ‘08. Good sturdy evergreen(gray) performer.

 

Callistemon viridiflorus was planted at the Battleship Oregon Mast in ’05. Several years earlier I planted one in my south facing parking strip at home. The home planting has performed with vigor and has formed a sturdy upright shrub. The Mast planting has been abused. In its second summer it was pulled out of the ground and left on the exposed ground for several days before I found it and replanted it. It has since re-established though does not show the vigor I expected. For some unfathomable reason (pun intended) it has been selected out by vandals and has been broken several times. This specific site has a history of such vandalism as it is the frequent location for many unscheduled ‘parties’. It also used to suffer heavy skateboard use/abuse which included crashes into the plantings.

 

x Chitalpa tashkentensis I planted one of these in South Waterfront in fall ’11 at the top of bank just south of the Newport Grill garbage enclosure. It grew some adding healthy looking growth and even flowered thinly. I did have it hand watered its first summer a couple of times before it showed too much stress. Other than having been pushed over and now possessing a tipped trunk, it is doing well and flowering strongly, summer ’14.

 

Choisya x ‘Aztec Pearl’ was planted at the Battleship Oregon Mast in ’05. It has shown good vigor, though has suffered from being broken twice by skateboarders/homeless youth(?).

 

Cistus ‘Blanche’ has been one of the more consistent performers wherever I have planted it. I first planted it in an arc in the fall of ’07 at the north end of Riverplace in section 1. These were planted in 1gal pots and have shown vigor from the beginning. They started to flop this summer ’12. Several more were planted in ’09 in small gauge pots and have grown just as strongly. Another is in section 2 near the top of bank and is doing well. A few were planted in ’11 between the Marina and Restaurant Ramps. These look good, but are maybe a little slow. As I said, overall, these are a good performer.

 

Cistus corbariensis was planted around ’00, the year after the Park was completed at South Waterfront on the steep south side of the Grassy Knoll, next to the David Evans Bldg. The street had been realigned for future development carving into the Park. It is growing in thin soil on top of course construction fill and rubble. These plants have shown good vigor and remain dense weed smothering plants.

 

Cistus ‘Elma’ Part of the original replanting of Riverplace up high in section 3 these have always done well. The plant tends to be a little lax with longer internodes than many Rock Rose so it is a little less kempt looking. I first planted this one at Duniway Park around ‘98. It’s still there next to the parking lot.

 

Cistus ‘Silver Pink’ This was part of the original Riverplace replanting project just south of section 4. They have never grown with much vigor, being low and open, providing space for weeds to sprout from within. Most are still in place. The A. Howard McMinn was planted as an eventual replacement, let them work it out. Since I change my maintenance approach, spraying less for one, this Cistus has rebounded.

 

Cistus ‘Snowfire’ Planted at Riverplace in section 2 in fall ‘10 . These are also in a strip just above the rip-rap. These have grown weakly and are thin.

 

Cistus x pulverulentus ‘Sunset’ The first Rock Rose I have grown planting it at home around ’02 in my parking strip where it performed with vigor. I planted it just above the rip-rap at South Waterfront between the Marina and Restaurant Ramps (over 40 plants). It shows good vigor. It is also at Riverplace in section 1 on the slope below the ramp going to the north breakwater dock where it is doing well, planted in ’10.

 

Cistus dansereaui ‘Jenkyn Place’ I planted these just south of the Restaurant Ramp above the rip-rap at South Waterfront. It has grown with vigor. With that success I planted more in fall . These have struggled a little.

 

Cistus obtusifolius These were planted in the two triangles in South Waterfront in fall ’10. They have shown good vigor and have formed uniformly dense mounds.

 

Cistus platysepalus I planted these in section 1 at Riverplace just above the rip-rap. They are growing with vigor. This and C. obtusifolius are the best performers of the low mounders for me.

 

Cotinus coggygria ‘Golden Spirit’ One was planted next to the electrical transformer at the top of the ramp to the Riverplace Marina in the fall of ’10. It has received very little irrigation and is growing slowly. The color and size of leaf is good, though by the end of summer there is a little scorching along the margins.

 

Cupressus sempervirens ‘Swane’s Golden’ Planted three at Battleship Oregon Mast in ’05. These have grown slowly but steadily and are strongly upright. Another was planted around ’04 in South Park Blocks in front of the Art Museum in the south bed. At SPB the soil was amended with 2” of pumice and topped with ¼-12 gravel. Still the soil is too rich, the site too shady and receives too much water even with the low precipitation MP Rotators. (The irrigation system was installed many years ago and separating zones was not possible because of the root growth of the massive Elm trees.) It has grown too vigorously and is somewhat lax. Like most mediterranean type plants they do best in dryer conditions with mineral soils.

 

Grevillea x Audrey I planted this immediately below South Waterfront’s South Overlook in fall ’11. It has grown vigorously and looks robust at the end of Nov. ’12. Continued growing and performing robustly through ’13, until December. Dead. Completely defoliated by spring ’14.

 

Grevillea juniperiana ‘Molonglo‘ did well initially but my one planting died this winter ’13-’14.  It was planted fall ’12 at the top of the bank in South Waterfront Park along the Esplanade just north of the group of Alders north of the North Overlook.  Again the soil could be deeper and better drained, but in the same immediate area the following Grevillea has done well.

 

Grevillea juniperiana ‘Xera Ember’, as noted above, is doing well.  There are several plants spread along the bank top and while they have shed a few needles, they have rebounded with good growth and bloom.

 

Halimium ocymoides I planted these in the fall of ’10 at the top of the bank between the Marina Ramp and the Restaurant Ramp and in the large triangle in South Waterfront next to the Espanade. The triangle planting which is flat I had amended with pumice and later mulched with ¼ 12 gravel. These have all done well and have continued to bloom well each summer. I added a few more in fall ’11 next to the restaurant’s garbage enclosure which have also performed well.

 

Indigofera pendula I know, not a mediterranean, but of Chinese origin…the flesh is weak. This was planted adjacent to Newport Grill’s garbage enclosure where the Romneya was, in fall ’11. It has done well since and flowered lightly. No supplemental water was given. The winter of ‘13/’14 killed it. Remember, I was pushing it here with regards to soil with slow surface runoff and compacted subsoil. Also, because of the grades of the larger Park and the Esplanade itself water was shunted into this area from the irrigation across the path. There was an Arbutus menziesii struggling in the area for a couple of years. Several other xerics, noted elsewhere here, have not suffered in the immediate area.

 

Grasses

 

Half the site at Riverplace, most of the southern portion, was seeded with Festuca rubra commutata in fall of ’08. I should have made the effort to do the whole site. This Fescue fills in between the clumping grasses and herbaceous material making a low, somewhat hummocky, cover and taking space otherwise available for weed growth.  The lesson is clear, don’t leave bare open ground, especially if you are not committed to doing what it takes to maintain it.  Most gardeners, though they may not mind weeding, don’t want to dedicate large portions of their lives doing little else but weeding.  Is the look worth it to you?

 

Carex tumulicola was added two years after the replanting project at Riverplace. Carex densa was spec’d and planted originally, but was a poor choice. It died out quickly unable to survive without heavy and regular irrigation. The C. tumulicola has done well and is beginning to spread out from the original plantings. I first planted this on the bank in South Waterfront up and downstream from the North Ramp around ‘04. It has also been planted adjacent to the Garden where it gets regular irrigation. This last summer, which lasted warm and dry to mid-October, stressed this one more than it ever had been before. This plant comes back strongly with the onset of fall rains. In more managed areas we have cut this hard to keep it more groomed, but have left it alone in all other areas to grow into a dense, lumpy, hummocky groundcover.

 

Helictotrichon sempervirens Blue Oat Grass was a common element in the original South Waterfront planting and it was repeated in Riverplace. Normally this is a low care tuff performer, but not here. Some of this died out, rotting out the crowns, from the winter wet, poorly drained soils, or rotting due to the irrigation it received for the initial several years because neighboring plants, on the same system, required the summer water to grow well and look good. Another problem was the issue of scale and their habit as a bunch grass. Bunch grasses grow by definition as distinct individuals, space is maintained around them so that they can display their character. This is a good scenario for weeds and over this much area, with the limitations imposed on us to protect the water and Salmon from the possibility of runoff/contamination our use of herbicides was strictly limited. With limited staff this was a no win situation. Preferred plants growing weakly, limited ability to control weeds either with herbicides or labor…plants decline/lose, weeds dominate and spread. This is basically what happened and is still happening.

 

Koeleria macrantha was planted at Riverplace in the big replanting project. The native June Grass was planted in sweeps from the top to the bottom of the bank with a few Sisyrhinchium thrown in. This grass peaks very earlier in the summer, goes to seed and declines leaving it susceptible to weed invasion. Unfortunately I kept trying to spray out weeds which probably killed out some of the perennials I had later added like Achillea and Symphyotrichum hallii and the Red Fescue I had overseeded the area with in an effort to diversify the planting and make it more resistant to invasion. But my spraying seemed to only open it up to even more Cat’s Ear and no doubt the annual Brome which arrived later. This grass was a good choice, but not by itself. Roundup and non-selective herbicides should have been avoided from the start. Using a broadleaf selective herbicide on the Cat’s Ear, which I ended up using later, is a better choice, but it is very hard in practice to limit your off target ‘accidents’ as you walk back and forth over an acre of landscape. It has a somewhat hypnotic effect and you must continuously pull yourself back from falling into an automatic’ mode. Weed control is problematic especially for those weeds with similarities to the plants you want to promote.

 

Muhlenbergia lindheimeri is a new grass for me. I planted a few in fall ’11 in South Waterfront at the top of bank south of the garbage enclosure and added a few more this fall continuing the planting southward. The first plants were too long in the pot and were stressed when I planted them. They haven’t completely grown out of it. This particular site is flat and very compacted. I probably should have done more to break up the subsoil to improve drainage and even crown the bed slightly. An earlier planting of Helictotrichon suffered in the winters from being too wet combined with regular summer irrigation. There will be no more irrigation.

 

Muhlenbergia ringens was planted the following year in the same area and near the top of the slope on the bank below 5 Flags. This species shows considereably more vigor with these conditions than did the Muhlenbergia lindheimeri.

 

I will be posting another article about growing and maintaining large plantings of ornamental grasses at a later date.

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