Drought tolerance is an interesting topic. I’ve written on it before, but now have some additional thoughts to add, in part because we have recently moved to much more arid Central Oregon. A drought tolerant plant in Portland is a very different thing than one here where annual precipitation can vary from around 13″, very rare, down to as little as 5″, commonly 8″. While Oregon in general is considered to be a mediterranean type climate with dry summers and wetter winters, Redmond’s climate is strongly influenced by drier continental patterns. This last January, ’23, we received only 1/4″ of precipitation while Portland had 7.32″ about 120 miles to our northwest, on the ‘wet’ side of the Cascades. Drought tolerant then means different things in different regions and can vary widely within a region along with soil conditions, slope and aspect (which direction a site is oriented). Generally speaking, drought tolerance refers to the ability of a particular plant to endure periods in which available soil moisture is below that needed to support the plant’s metabolism. A tolerant plant can ‘bridge’ these naturally occurring ‘dry’ periods. An intolerant plant will suffer cellular, even structural damage and may be unable to flower and produce seed. Health is compromised should the drought last too long, resulting in internal physical damage and leaving it more subject to infection or infestation. A drought tolerant plant will have the capacity to respond in a healthy manner when soil moisture levels return to those that support active growth. Within these limits the stress it accrues does not compromise its health…beyond it though….Damage is accumulative. String a series of drought periods together and a plant’s capacity to recover is compromised. Because patterns of precipitation, of water storage and movement, vary widely across the earth, regions and sites have different plant communities associated with them. The condition of drought stress then varies with the location and the species. A drought tolerant plant on one site may crisp on another drier one. Of course this can work in the opposite sense as well, that a site may be too wet, but that’s another story. In the case of the PNW and many other regions, it is also the timing of the precipitation, when it occurs during a plant’s cycle of growth and dormancy. Continue reading
Category Archives: Design
Spreading the Wealth: Taking Advantage of Monte to Broaden a Teachable Moment
I’ve been taking advantage of people, striking when they are most sensitive, hungry for anything that is outside of their homes and families…I’ve been hanging informational signage amongst Monte’s floral neighbors as they come into bloom, not all of them. Some will remain anonymous like my Aristolochia semperivirens, an unassuming Dutchman’s Pipe, that is only noticed by the more discriminating of visitors. Others issue stronger ‘calls’ and so signage seems appropriate. Many people are taking the time to read them or take pictures of them for later consumption or to make sure they don’t forget. Many thank me for them. Who thought ‘school’ could be so cool! Anyway here is what I’ve hung out in the garden. Some will come down as their season ends, like the Pacific Coast Iris, others are waiting in the wings.
My Agave is flowering. The ‘spike’ you see growing upwards is the ‘peduncle’, the main flowering stem. As it meets its maximum height ‘branches’ will form near the top, from beneath the ‘bracts’, the tightly adpressed leaves, on which will form the yellow flowers. It will form a panicle, a ‘candelabra’ like structure. Agave are monocarpic, meaning they only flower once and then die, after it produces seed. It is 20 year old. Many Agave produce ‘offsets’ or ‘pups’ that can be grown on into mature plants…not this one!
This is a mountain species from Mexico’s Sierra Madre Orientale, where it is found between 6,000’ and 10,000’…not from the desert. This species is relatively new to the trade and was only formally described in 1996, 24 years ago. I’ve been told that this might be the first one to flower in the NW. Its native range experiences a temperate climate and receives its heaviest rains late summer-early fall during the hurricane season. It can experience freezing temperatures and even some snow there in open Oak-Pine forest. It begins its flowering process in Fall, then ‘stops’ for a period during winter, finishing the process in Spring/Summer. Most Agave are tropical/sub-tropical plants from deserts and are grown here in pots. There are 200 or so species, 3/4 of which are endemic to Mexico, found only there, none are native outside the Americas. Only 22 species are found in the US, from California into Nevada, Utah, Arizona, New Mexico and Texas. 3 are native to Florida.
Portland and the Maritime Pacific Northwest provide challenges to growing any Agave species and hybrid. Agave are native where climates tend to have most of their rainfall in summer. Here we have dry summers and wet cool/cold winters…this is the opposite of what most Agave need and will lead to rot and/or fungal foliar disease that can disfigure or kill most Agave species. Siting considerations are extremely important. They generally require full sun and excellent soil drainage. Here good air circulation helps foliage dry in winter. Sloping sites also help with soil drainage. Tilting the plant when planting is helpful as it helps the crowns stay dry. Some gardeners plant these under their eves or erect shelters over their plants to keep the crowns dry over winter. Agaves will require some summer water to grow well especially if they sit in dry soil all winter and spring….
Many Agave are becoming rare across their natural ranges in Mexico because of development and agriculture, a cause which threatens so much of our own natural flora in the US and around the world.
This species is not used to make Tequila! In its home range Agave are pollinated by hummingbirds, insects and nectarivorous bats, bats which are non-native here.
(False Red Yucca)
There are seven species of Beschorneria, from forests of the higher mountains of Mexico down into Guatemala. This is the most northerly species occurring in NE Mexico, not far from the range of Agave montana. Unlike their cousins, the Agave, all but one of these are ‘polycarpic’, they can flower year after year. These form a substantial rhizome which spreads gradually when the plant is well sited, forming colonies. This one does so only slowly.
Another Asparagus family member, hardy through our zn8a, down to 10º for short periods, if you can keep the crown dry enough. This one struggles a bit and I have to remove a fair amount of rotting leaves every spring…I should move it and it would do better, but I haven’t…it wants better drainage. This particular site is a little wet close to our house which tends to concentrate rainfall a bit without any eave over hang to catch it.
As an open pine/oak forest dweller these are tolerant of relatively shady sites. Mine get some shade.
It’s inflorescence typically form these bright red stems with its sparse branching and hanging, narrow, bell shaped flowers. Part of their corolla is green.
At the top of my stone steps is a selection of another species, Beshorneria yuccoides ‘Flamingo Glow’, which has a buttery colored mid-rib on each leaf. from forests of the mountains of central/eastern Mexico.
(Tower of Jewels)
There are 70 different species of Echium and several subspecies, in the same family as the commonly grown Borage. 27 species are endemic (occur no where else) to macronesia, the Canary, Madeira, and Cape Verde archipelagos lying in the eastern Atlantic close to Portugal, Morocco and west Africa. While the continental species are all herbaceous, dying to the ground over the winter, all but two of the island species are woody, with permanent stems. Echium wildpretii is one of these two.
Echium wildpretii can grow as high as 10’ in its home territory. It is generally a biennial, flowering in spring here, though sometimes, it can ‘wait’ and bloom the third spring. It is monocarpic, dying after producing seed. This plant is just under 9’ and is the tallest individual I’ve ever had in the 15 years of growing this. The plant grows in the ravines of Mount Teide, 12,198’, a volcano on Tenerife, 28ºN latitude, in the Canary Islands, so it has a very restricted range. It requires full sun and arid/dry conditions. With our much wetter winters it is best that you provide this with very good drainage as growing them in cold winter wet soil will decrease their cold hardiness and could lead to rot. Plant on south facing slopes and retaining walls with good air circulation. It is marginal, said to be hardy down to 23 °F.
The species E. pininana, the other Macronesian herbaceous grower, goes to 13’ having much the same form with blue flowers. E. candicans is a short lived woody shrub, which grows to 6’, both are grown here as well. In California these two and others are common some often escaping into the wild and crowding out native species. Here, these are marginal and survive only in protected areas killed by normal to colder winters.
Check my blog at Garden Riots. Annie’s Annuals sells several of these: https://www.anniesannuals.com/search/?q=echium
Grevillea x ‘Pink Pearl’
Grevillea is a genus of 360 species of flowering plants native to Australia and north and west to the Wallace Line. They vary from ground huggers to a tree over 100’ tall. They belong to the Protea family which includes many bizarre and large cut flowers used in the florist industry. They are pollinated by many Lepidoptera, butterflies and moths as well as by Honeyeaters, a group of nectar feeding birds native to their home range related to South African Sunbirds, but not at all to our Hummingbirds. Hummingbirds and bees visit these here.
Most Grevillea are not hardy here in the NW so choose judiciously. To find reliable plants check out the offerings of Xera Plants on SE 11th and or take the trip out Sauvie Island to Cistus Nursery, they have a section of Australian plants. There is a great review of NW hardy Grevillea at Desert Northewest’s site, https://www.desertnorthwest.com/articles/grevilleas_revisited.html
Grevillea readily hybridize. This is thought to be a hybrid of G. juniperina x G. rosmarinifolia. If you give it what it wants it is hardy down to 20ºF, maybe lower. I planted this one 6 years ago here. One winter, ’16/’17, I lost about 1/3 of the top. That was Portland’s fifth coldest winter ever in terms of number of days with freezing temperatures…so not typical. (https://weather.com/storms/winter/news/portland-oregon-worst-winter-city-2016-2017) I suspect another degree colder or with another day of sustained freezing, I would have lost the entire plant.
These are relatively fast growing and can take a hard pruning. In Australia these are often used as hedge plants causing them to grow densely with their pokey needles, quite a barrier! I prune mine regularly to limit its size while retaining its softer look with drooping branch tips.
These are sun lovers and require well drained soil here. They are drought tolerant in the Pacific NW requiring no water after establishment. It is essential that should you choose to fertilize that it include NO PHOSPHOROUS!!! Phosphorous is plentiful in our soil already and adding anymore can prove deadly to Grevillea and also to most all members of the larger plant family. These come from regions with phosphorous poor soils and are very well adapted to searching it out, so…don’t add any!
x Halimiocistus wintonensis ‘Merrist Wood Cream’
This Rock Rose is a hybrid between two different genera Halimium and Cistus, a relatively rare even as species from different genera aren’t generally capable of crossing successfully. The parents are both Mediterranean plants and this plant benefits from growing under like conditions, warm to hot, dry summers and cool/mild and relatively wet winters.
This plant has grown here for 10+ years on this south facing slope in unamended soil. It benefits from a light cutting back after flowering to help keep it compact and to keep it from falling/splaying open. All of the Rock Roses have a tendency to splay open with time here as our rich soil tends to push them to produce extensive soft growth. Don’t cut these hard, below healthy growth, if you do you are likely to end up with dead stubs unable to resprout. I’m planning to take cuttings of this, root them and replace this plant as it has gotten rather ‘leggy’ over time.
There are many fine Rock Roses available from these two genera that can be grown here.
Lobelia laxiflora ssp. angustifolia
This Lobelia, with its narrow hot red tubular flowers, from Mexico, is reliably evergreen here except over our coldest winters, which can kill it to the ground, but from which it springs back. It often blooms for 7 months or more in the year. As you might guess it is attractive to hummingbirds. This plant is rhizomatous and in too good of conditions with summer water, has a tendency to spread, though it does so compactly. It is better ‘behaved’ under drier, more spare, conditions.
Lobelia are a large and varied genus with 415 species occurring primarily in tropical to warm temperate regions. I also grow the less commonly grown species type, sometimes called ‘Candy Corn Flower’ with broader leaves which is less robust for me here, but showy in its own way.
I grow Lobelia tupa on the east side of our house. It’s a large growing Lobelia from the Andes of Chile with hooking dark red large flowers. I have others on my list including the large pink flowering species, L. bridgesii, to acquire and am somewhat enamored with the ‘Tree Lobelias’ limited to the Hawaiian Islands.
Mimulus aurantiacus ‘Jeff’s Tangerine’
Sometimes known as “Sticky” or “Bush Monkey Flower” this plant is native from SW Oregon down through most of California into Baja. A ‘sub-shrub’ this has a somewhat woody base from which sprouts softer herbaceous stems that carry the leaves and flowers. Found from coastal bluffs east into the Siskiyou and Sierra Nevada mountains, these are ideally suited to our mediterranean climate with its summer dry/winter wet precipitation pattern.
Typically, where I’ve seen it growing in situ it is taller than my plant with a much more substantial woody base. At Point Lobos, on the central California coast, these can be over 4’ tall and form impenetrable thickets. Here with our rich soil it grows more lushly and flops. My plant is ten years old and will bloom all May through September in waves, almost never completely out of flower.
Place it in full sun. Mine receives only sporadic summer water. It grows in unamended soil on a south slope so it has good surface drainage. It benefits from free air movement and good soil drainage. There are several color forms available from specialty nurseries.
Pacific Coast Iris
There are 12 Iris species in the group native to our region stretching from southern California northward into Washington state, in a narrow band between the ocean and the Cascades and into California’s western Sierra Nevada. Most of these are limited to California and southern Oregon to areas that receive enough rain and are often limited to places closer to the coast. The Willamette Valley and Washington is mostly limited to one species, the deciduous, woodland edger, Iris tenax.
Hybridizers have taken advantage of their tendency to cross and are found in a wide range of jewel like colors, white, to yellow, red, russet, blue and purple. The hybrids are evergreen. These must generally be searched out as their production is relatively low because these Irises are difficult or impossible to grow anywhere else in the country because of soil and climate differences too far out of their ability to adapt.
The hybrids are drought tolerant in our western gardens. Plant them with plenty of sun, then water to establish. Don’t plant them anywhere where the soil remains soggy into the summer, they need to dry out. It is important to leave them undisturbed after planting. If you choose to move or divide them, wait until the fail rains, when they are producing new roots. They will likely die if messed with during the summer. See my blog: gardenriots.com.
Sphaeralcea x ‘Newleaze Coral’
The genus Sphaeralcea is native/endemic to the intermountain west of North America, occurring between the Rocky Mountains and the Cascades and east of the Coastal mountains of California. Some can be found in eastern Washington, Oregon and Idaho on south into northern Mexico. They like sun, heat and thrive in poorer mineral soils and are drought tolerant here once established.
‘Newleaze Coral’ earned its garden pedigree in the UK and is a stellar performer here in xeric beds. Sphaeralcea is a member of the large Mallow family which contains 244 genera with 4,225 known species. Well-known members of economic importance include okra, cotton, cacao and durian. There are also some genera containing familiar ornamentals, such as Alcea, Hibiscus, Malva and Lavatera, as well as the genus of trees, Tilia. Commonly called Globe Mallows, this Sphaeralcea will easily bloom for 5 months bookending the summer months.
Gardening in Public, Charismatic Mega Flora and the Need for a Public Horticultural Intervention
We ‘need’ charismatic mega-flora today, plants that scream out to even the most plant blind of us to take notice, those that create such a sudden and uncontrollable ‘stir’ within us that our simple glimpse of them breaks our momentum, our chains of thought, interrupting whatever we’re doing in that moment bringing about a reflexive interjection, cause us to take notice, create an uncontrollable urge to stop what we’re doing and come back for a closer look! To tell our parents, partners or friends, to drag them back, for a repeat performance or to see if what we saw is really there or merely a mistake of perception. And they do come back. I see them every day, sometimes dragging disinterested friends to see this unimaginable impossibility. I hear them when I’m out working in the private part of the garden with excited voices, sometimes expletives, “Look at this ‘F@#$ing’ thing! Can you believe it?” I love this. They’ve come for ‘Monte’!
On Our Expulsion From the Garden: How Our Ideas of the Garden Shape What We Do
There are those who argue that life is short and violent, that we have nothing to look forward to other than our deaths…so we might as well grab for whatever we can now!….that is the path of the nihilist and the greedy, it serves as an excuse, a rationale for their choices, following an ethic of ‘why the hell not!’ This is consistent with the ‘beliefs’ of those who feel the weak get what they deserve, that anything that opposes their idea of dominance, is weakness and failure and they pursue it with the righteousness of a ‘true believer’. “Only the strong survive”. If our gardens can teach us anything it is instead that, ‘He/She who has the graciousness to take only what they need and gives back whatever they are able to, live on through the love and lives of those and that which they’ve nurtured, helped, befriended and mentored along the way and in this way have helped build a richer, more complex and diverse world.’ Our true legacy will be best expressed in the richness and health of the world we leave behind, of those that we’ve loved and taught. As competitive as the world is, it is this positive, cooperative, supportive aspect of life that makes it all possible. While the world is divided into heterotrophs and autotrophs, those that must consume to live and those able to grow and metabolize that which they need from the world around them, it requires them both, working in a balance to sustain them all. We humans, ultimately, cannot be any different if the world is to continue on. Continue reading
Our Gardens as Teachers
Of all the things our gardens do for us, arguably the most important is their role as our teachers, even in winter when a temperate garden ‘rests’, its surface crust or top few feet, frozen, maybe sheltered beneath the cover of snow, or, as ours so often are, simply too cold for active plant growth, the soil wet, the rain too heavy to percolate fast enough down through its layers, without the active aid of either the direct heating of the sun or its effect on plants, through evapotranspiration, pumping water back into the air as the plants grow. Gardens teach patience. They encourage us to become more careful observers…to think and plan, to anticipate and prepare, to understand that there is more going on here than we can readily see…and they teach us about faith and trust in the natural world, that there is always more going on than we can see. Continue reading
Gardeners, Garden Designers and Their Role in Saving the World!
Loree, of Danger Garden, posted a comment and a link in Facebook a few weeks ago, to a story about a gardener in Australia and what gardening meant to him in the online Planthunter blog. It elicited an array of comments, both supportive and not. She posed the question, are the ‘best’ gardens the products of an ‘organic’ process, produced by the gardeners themselves, in intimate relationship with their place? Which raised the question, can garden designers create truly beautiful gardens for others on landscapes that they don’t have this personal connection to? Her question caused a flurry of comments, several containing a lot of emotion. Loree’s simple question produced a fair amount of ‘heat’. I found the array of responses, and the conflicts they brought to light, provocative and I think a lot of that heat comes from the fact that our modern society has become largely estranged from the natural living world. I spent quit a bit of time thinking about it. Below is what it prompted in me.
I retired from Parks after a career of mostly fixing and tweaking designs that I had nothing to do with, but ended up resposnisble for, tearing out neglected landscapes that had became grossly overwhelmed and out of balance by overplanted and aggressive plants, others that were lost to weeds and invasives, others still that were stomped out and abused by the public largely because of their siting and the public uses which they had to endure, a public that is often indifferent to the living world and its requirements and their resulting traffic patterns that designers thought that their massing could channel where they wanted. I did this while working within an organization that undervalued the plants and the horticulturists who cared for them….I was still able to create a few places that the public responded to positively. Continue reading
A Closer Look at Jimi’s Beautiful Obsession, A Review of Chosen Plants From his Presentation, Part 1
It would seem that gardeners are a difficult lot! For those of us intent on gardening with ornamental plants we are continuously drawn to the exotic and novel, sated less and less by the plants in yesterdays’ garden…at least until those have had suitable time to have fallen out of fashion and are rediscovered. For most of us it is the plants we’ve never grown, or even seen before, that draw us. This is as true when we ourselves are novices as it is many years later. Sure, we all have more than a few long term relationships with particular plants, but we seem forever subject to the seductive calls of the unknown (to us)! For many of us this is at no time more true than when nurserymen, on the ‘cutting edge’, and plant explorers come to town, especially if they come bearing pretty pictures…Even mores so when paired with the opportunity to acquire them. Instant gratification. It is a conspiracy you know. Continue reading
The 2018 Garden Riots Awards for the Northwest Perennial Alliance Seattle Study Weekend!
These are my own personal favorites for the Northwest Perennial Alliance’s Study Weekend in Seattle. This is not official, nor the result of even a casual survey of attendees, just my own selfish opinions….
All of the speakers were great!!! I mean this, seriously. I am not known for my PC’ness or empty platitudes. First, goes to the brother and sister team Jimi and June Blake from Ireland for their informative and infectious talks on their gardens and plant loves, for the attention that June brought to us of the history and unique contexts of the place where she gardens, her design sense and ways of working. I particular enjoyed Jimi’s understated wit and sense of humor and our shared plant sympathies, including his for Salvias and his many other favorites as well as willingness to tear into and completely revamp his own garden. If I’d only had the list of plants that they chose to talk about, that would have been plenty enough to have gotten my attention, but their abilities as presenters, as interesting people and characters, brought it all ‘home’. Loved the ‘blue’ Jimi. You’d never catch me dead in it, but on you…it fit perfectly. Continue reading
Argyle Winery: A Look at a Landscape in Dundee as an Example for Those on the Trail to Xeric Design and Sustainability
I don’t usually do this, write about a particular landscape with which I have no history, so this is a bit of a departure for me. I’ve know Sean Hogan for quite a few years, consider him a friend and a highly influential mentor of sorts. His encyclopedic knowledge of plants, his boundless enthusiasm, has been infectious and inspirational over much of my career as a horticulturist while I was working for Portland Parks and Recreation. I’ve benefited from the existence of his nursery and his commitment to horticulture picking his brain for plant and design suggestions as I attempted to broaden my own repertoire. Continue reading
Failing Landscapes, Failing Practices: A Look at Tri-Met’s Landscapes and How We Could Do Them Better!
About a year ago I posted a series of three articles on Tri-Met’s landscapes along the new Orange Line. They were a critical assessment of their design with many photos and explanations for my criticisms. I had a brief correspondence with the project manager after the first two before he stopped responding. I had asked about the maintenance schedule that they had with the contractor who would be doing the work. I did not receive it. Part of the reason was mine, as new ideas came up for me, my interest wavered and I moved on. Still, I’ve never received anything. Now, a year later, I decided to reassess the first portion of the landscape that I wrote about, as it is a section I regularly walk and ride by bike to downtown or to just get out. I would encourage readers to see my previously posted reviews. Continue reading