Tag Archives: Drought Tolerance

On Plant Drought Tolerance and Gardening in the Arid Oregon High Desert

The Dry Canyon in Redmond, Oregon, which for 200-300,000 years contained an earlier version of the Deschutes River. The rivers course was changed by an eruption from the Newberry Volcano, a massive shield volcano with over 400 vents 40+ miles to the south. A later eruption partially filled the canyon with lava. In this section the canyon was filled raising its floor so that it’s around 70′ deep, its two rims separated by about 700′.

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