High times for low-water plants
May 4, 2023 | View PDF
Gardeners increasingly look to drought-tolerant varieties that beat the heat
The summer of 2015 was a turning point in the Northwest, which suffered the longest heat wave in 75 years. Portland had more days above 90 F than any other year in recorded history up to that time. That year marked a noticeable shift in gardeners seeking low-water plants to include in their yards.
But 2015 had nothing on 2021, the year of the heat dome, with some of the most extreme weather events globally and record-breaking high temperatures in the Pacific Northwest and into northern California, western Nevada, and British Columbia, which broke a temperature record hotter than Texas’s.
That year marked a sharp upturn of people specifically looking to not only include plants with modest water needs but to actually transition or replace lawns and plants with water-conserving landscapes, said Greg Shepherd of Xera Plants, a Portland, Oregon-based nursery that specializes in climate-adapted plants.
The shift is not only regional; it is being felt across the industry and across the country. Nothing marks that more than online mainstream reporting. From Southern Living to the Los Angeles Times to Real Simple magazine, the attention of the mass market is sturdily fixed on low-water plants, sometimes referred to as drought-tolerant or climate-adapted.
“As customers are increasingly aware of water usage and water limitations, we are definitely seeing a sharp increase in demand for drought-tolerant plants,” said Darren Morgan at Shonnard’s Nursery, Florist and Landscape, a retailer in Corvallis, Oregon.
As well, the plant breeding industry has its full attention on producing more plants that have better drought tolerance and are more heat tolerant and resistant, said Judy Alleruzzo, house plant and perennial buyer at Al’s Garden & Home and co-host of the Garden Time podcast.
Here, we’ll discuss some of the most popular low-water perennials and ornamental grasses making their mark today.
Like many of the plants in the low-water plant category, Achillea (yarrow) species and hybrids fit into the trend of home gardeners investing in landscapes that support pollinators and wildlife. These plants are popular for their versatility.
“They bloom for very long periods of time through the summer and are attractive to many different pollinators,” Morgan said. “Our local native Achillea millefolium is a sterling example, with white flowers — though yellow and pinkish plants crop up in the wild — borne for many weeks in the middle of summer in anything except the darkest or the wettest environments.”
Achillea adapts well to most levels of sun or shade and moisture, something that not all the plants in the drought-tolerant category will do, he explained. They’re easy to care for and deer resistant, and breeders have introduced a selection of short to tall varieties that bloom more often, Alleruzzo said.
“Once people discover Achillea, they become true believers,” she said. The long-standing, larger variety ‘Moonshine’ (zones 3–9, 1–2 feet tall × 2 feet wide) has “beautiful, sulfur yellow blooms, stunning.”
For smaller gardens, the newer dwarf ‘Little Moonshine’, at only 12–14 inches, is turning into a popular addition in container gardens, as is the similarly sized New Vintage™ series, which comes in several eye-catching colors.
Agastache (hyssop) makes up some of Xera Plants’ best-selling perennials, Shepherd said, and the nursery’s introduction Agastache ‘Electric Punch’ is a standout with 3-foot stems producing vibrant orange flowers that fade to pink as they age. Flowers continually bloom from May through October and are attractive to pollinators. It’s quick to establish, easy to grow and attracts hummingbirds, which is always a selling point, Shepherd said.
Calamintha needs a little more watering than other low-water plants, Shepherd said, but it’s a reliable seller that is a good filler, which is what often captures customers selecting this plant. It does not spread by underground runners, produces white clouds of flowers for a long bloom season, and mixes well in borders. Calamintha nepeta ‘Montrose White’ (zone 4, 2 feet × 2 feet) is a tough, tidy, low perennial that attracts many pollinators.
Ceanothus (California lilac) is the largest genus of native shrubs. It is the hardiest of the evergreen and blue-flowered species, Morgan said, with excellent varieties such as the fast grower ‘Victoria’ (zone 8, 10 feet × 10 feet) and the denser, compacter ‘Skylark’ (zone 7, 1–2 feet × 2–3 feet), with yellow variegated leaves.
“All of these California lilacs are evergreen, and they bloom heavily in the spring and often again more lightly in the fall,” he said. “The blue flowers are lightly scented, and very attractive to bees of all sorts.” Shonnard’s also sells a lot of C. impressus, which Morgan said is not as hardy in Oregon.
Clarkia is a long-blooming annual that reseeds year after year, Shepherd said, to yield a flowering patch. “They germinate with the fall rains, overwinter and then bloom. If you are okay with self-seeding, that and meadowfoam (Limnanthes alba) perpetuate year after year, and are supportive of native insects as well.” Clarkia amoena ssp. lindleyi ‘Farewell to Spring’ (zone 6, 2 feet tall), like other West Coast native annuals, thrives without irrigation, and reseeds and germinates on its own.
Echinacea (coneflower) is the most popular low-water flowering plant Shonnard’s sells, even as Morgan said there are other perennials with better drought tolerance. There is great variation in types, and they make up a huge volume of sales in low-water plants.
Epilobium (Zauschneria) septentrionalis ‘Select Mattole’ (California fuchsia, zone 7, 6 inches tall × 2 feet wide), sometimes called hummingbird fuchsia, is a West Coast native perennial that Xera Plants can barely keep on the shelf because of its name recognition. A low grower, it has a long bloom season of vibrant orange trumpet-like flowers on silver foliage needing minimal water.
Gaillardia (blanketflower) is “more consistent in overall performance than the similar looking Echinacea,” Morgan said, but equals it in display and pollinator suitability, and will outperform it. Gaillardia flowers in vibrant yellow, orange and red, and will bloom spring to summer or all summer long. The native Gaillardia aristate (zone 3, 2–3 feet tall) is one of the larger blanketflowers, with boldly bicolored yellow and orange petals.
Morgan counts Hesperaloe parviflora (red yucca, zone 5) as an up-and-coming plant in the low-water plant category, that he highly recommends. The durable evergreen with yucca-like lower foliage bears 5–6-foot spikes of orange flowers in the summer. “Except for water-logged soil, it is a solid performer” and attracts hummingbirds.
Lavandula is an “iconic” plant, Alleruzzo said, known by many gardeners who rush to any sale of the plant even more so than they do to general perennial sales. Once established, it is drought tolerant, a great pollinator, deer resistant and useful dry or fresh. It’s low maintenance, takes full sun and is forgiving. For customers with limited space and looking for continual blooms, Alleruzzo recommends Lavandula stoechas (Spanish or French lavender) over Lavandula angustifolia (English lavender).
Perovskia atriplicifolia (Russian sage, zones 4–9) has the common trait with yarrow and lavender of being deer resistant, attractive to bees and low care, and showing beautiful gray-green foliage. Like lavender, it is also sometimes listed as a subshrub for its size (usually 3–4 feet tall and wide) and woodiness. Alleruzzo said newer breeding is bringing on compact growers that will appeal to customers, like P. atriplicifolia ‘Little Spire’ and P. atriplicifolia ‘Bluesette’, which has the same long blooming period and other attributes, but half the size of the species.
An older classic, Rudbeckia fulgida ‘Goldsturm’ (black-eyed Susan, zone 9, 2 feet at maturity) “is still a top perennial, with masses of black-centered yellow flowers produced over a very long summer bloom season, whether irrigated or not,” Morgan said. It grows at a moderate pace to fill as much space as you allow it to take, he said. “ ‘Goldsturm’ makes up a lot of our sales.” It’s reliable, with a bold presence in tough conditions.
Stonecrop had a recent nomenclature shift from Sedum to Hylotelephium, but everyone is still calling it Sedum, Alleruzzo said. Stonecrop comes in many forms, from creepers to uprights; they are easy for beginners, attract pollinators and take almost no care.
Old-fashioned ‘Autumn Joy’ (Hylotelephium ‘Herbstfreude’, zones 3–9, 1–2 feet tall and wide) still outsells newer varieties, Alleruzzo said, because of its great performance in low-fertility and low-water situations, bursting with flattened heads of rosy-colored star-like flowers that turn coppery in fall. A lower-growing option is Sedum spurium ‘Dragon’s Blood’ (4–6 inches tall × 24 inches wide), which starts burgundy in the summertime, greens up as it matures, turns a darker burgundy in the fall, and keeps its foliage during the winter.
Cistus (rockroses) as a group are popular, Morgan said. “The old classic Cistus × ‘Purpureus’ (purple rockrose, zones 8–11, 4 feet tall × 4–6 feet wide) is one of the showier and larger types,” and as an evergreen, satisfies the request by gardeners, especially those who move from warmer clients, for year-round interest. Another bestseller is Cistus × skanbergii (dwarf pink rockrose, zones 8–10, 2–3 feet high × 4–5 feet wide), a low-spreading variety needing little care. Morgan’s favorite, the variegated Cistus × hybridus ‘Mickie’ (zones 7–10, 18 inches high × 36 inches wide) “is a very low-spreading rockrose with white flowers [from May to July “with stunningly bright yellow variegated leaves. It sells out as soon as I have it.”
Grasses and sedges
Pennisetum spatheolatum (veldt grass, to zone 7, 20 inches tall × 3–4 feet wide) is a semi-evergreen to evergreen grass native to South Africa that does well without water and blooms all summer on 3–4-foot stems. The mound is graceful, with movement from the flowering heads, Shepherd said, and it’s an easy-maintenance grass that only needs to be cut back once in spring.
As a solidly drought-tolerant grass, Morgan recommends the consistency of the compact P. alopecuroides ‘Hameln’ (fountain grass, zones 5–9, 2–3 feet tall and wide). Dense clumps shoot out arches of bottlebrush blooms that change colors in fall, when the leaves turn from yellow to bronze.
Sesleria autumnalis ‘Campo de Azul’ (to zone 5, 1 feet tall × 2 feet wide) is also one of Xera’s best-selling grasses, a durable, moderate-sized grass that fits with other low-water perennials and shrubs, Shepherd said. An evergreen, it forms expanding clumps of stiff, upright foliage and gray/black flowers frosted with light yellow pollen.