In June, we wrote about weatherproof gardens mentioning a trial under way at the University of Washington along with five other Western universities studying “climate-ready” plants. University of California Davis was the pioneer of the project, and I was excited to read in Horticulture magazine that UC-Davis has released some of the best performers in its plant irrigation trials, https://ucanr.edu/sites/UCLPIT/AWARD_WINNERS/BWUCDavis/.
These plants fared well despite being given only 10 to 30 percent of the water lost through evapotraspiration, a combination of the plant’s natural “breathing” and the effects of air temperature, sunlight, humidity and wind. They could make your gardening a little easier, and your water bill a little lighter.
This trial took 24 varieties of plants and subjected them to three levels of irrigation, adjusted based on changing weather, and rated the plants’ performance based on specific health criteria such as growth rate, number of flowers and appearance. It’s important to know that the first year, all the plants received full irrigation to establish, so that needs to be a given for all your new plants. In your garden, I’d even say two years for larger plants or harsher conditions.
The “Blue Ribbon” winners that thrived in the harshest, lowest water conditions are not all hardy in Seattle, but some make wonderful container stars. Zones refer to the U.S. Department of Agriculture Hardiness Zones. Seattle is 8b, so plants tagged zone 9 or higher are not likely to endure our winters without protection, and 8s might still need some help in a cold spell.
Some are brand-new to me, and several, believe it or not, are roses. UC-Davis has been running the trials for several years.
This list includes both the latest and the greatest, in no particular order.
“Blonde Ambition” Blue Grama grass (Boutela gracilis ‘Blonde Ambition’) — this grows flanking my front steps and I appreciate it more every year. It will turn tan over winter, but keep its adorable little seedheads, which look like hortizontal flags — or I like to say, flying eyebrows — upright for interest until I cut them back in late spring. They are blooming again by June. Full sun, Zones 4-9.
Snowy River Wattle (Acacia boormannii) — a sun-loving evergreen shrub from Australia with dainty yellow spring blossoms that can reach 15 feet. Full sun, Zones 8-11. This one will need a protected spot to thrive, and I’m guessing may have to grow back from the roots some winters, keeping its height in check.
“Juke Box” pyracomeles (Pyracomeles ‘NCXP1’) — a small-leaved compact evergreen that could make a nice replacement for boxwood (Buxus) which can be subject to blight. Only 3’ x 3’. Full — part sun, Zones 7-9.
“Tiny Tangerine” bulbine (Bulbine frutescens ‘Tiny Tangerine’) — a South African succulent groundcover that resembles a mat of condensed Aloes with stalks of orange flowers in summer. Full – part sun, Zones 8-10.
“Meerlo” lavender (Lavendula allardii ‘Meerlo’) — not hardy, fewer flowers, but oh, that foliage! Bold cream-variegated, fragrant foliage in a compact shape about 2.5’ tall and wide, it would be a fabulous accent to a container or an herb bed. Full sun, Zones 9-10. A visitor favorite at trials.
“Pink Supreme” Flower Carpet rose (Rosa ‘NOA168098F’) — a disease-resistant improvement on earlier Flower Carpet series, a perpetual pink mound of flowers. 2.5’ x 3.5’. Full sun. Zones 4-10. 2020
“Limoncello” rose (Rosa ‘Meijecycka’) — an everblooming shrub rose with masses of single-petaled yellow flowers that morph from lemon to cream. 4 x 4. Full sun, Zones 5-10.
“Delta Eclipse” Crepe Myrtle (Lagerstroemia indica ‘Deleb’) — vivid pink flowers pop against glossy purple leaves. Deciduous small tree with gorgeous winter bark, to 10’ x 5.’ Full sun to part shade, Zones 7-9. A staff favorite.
‘Lime Tuff’ dwarf mat rush (Lomandra ‘Bushland Green’) — another Aussie, this one is for looking, not touching — the flower spikes are small but intimidating and are best trimmed with thick gloves in late winter. However, it’s compact, neat, and ever-lime, adding a punch of texture and color to hot spots. Full-partial sun, Zones 8-11. A staff favorite.
Until we get local results from UW’s trials, here is a starting point for a xeric shopping list that should be able to survive a certain amount of heat and drought. Ater you baby them like your indoor orchids for a season or two.