Do It Yourself : Help Line : Dry Spells Don’t Bother Some Plants
Question: The summer sun and heat are just baking some of the plants in my garden. Can you recommend some plants with nice foliage and flowers that will tolerate full sun and reduced water?
C.S., Irvine
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Answer: The list of possible plants to include in the more arid sections of your garden is quite long (entire books are written on the subject). Some of the more water-efficient choices include many California natives and plants from the Mediterranean, Africa, Australia and South America.
Certain plant families tend to better tolerate little water, such as succulents (ice plant, many Euphorbia, sedum, agave, aloes etc.), because of their thick, fleshy stems and leaves coated with a waxy substance that keeps them from drying out.
The majority of plants with gray or silvery foliage tend to have low water requirements as well, and thrive in hot, arid conditions. Plants with deep taproots, such as those in the poppy family, are also good choices, because they are able to “tap” into water reserves far down in the ground. Many plants with hairy leaves are also protected from reflected sun, heat and drying winds.
A large number of shrubs most suited for a hot, dry climate such as Orange County’s flower in the spring and then rest in summer. If a lot of summer color is what you are looking for, you will need to incorporate annuals and perennials more tolerant of heat among the shrubs. If you decide to plant California natives, remember that many of them go into a semi-dormant state in summer. Watering them at that time can cause root rot and even death.
The following are some of the more resilient perennials, flowering vines and shrubs to consider that will tolerate full sun and drier conditions:
* Achillea (yarrow). These perennials are known for their feathery foliage and bright flowers. They prefer moderate amounts of supplemental moisture, but once established, their deep taproots allow them to tolerate dry periods. There are numerous cultivars to choose from, some of which spread in mats like A. tomentosa (6 to 12 inches high and 18 to 24 inches across), and others that form clumps such as A. millefolium (18 to 30 inches high in numerous colors), and A. taygetea ‘Moonshine’ (12 to 18 inches tall with bright yellow blooms).
* Artemesia. Grown for their superb foliage, tolerance of reflected heat and drought, and usefulness for erosion control. A. ‘Powis Castle’ is an excellent choice if you have the space (3 feet high and 5 feet wide). A. Ludoviciana (‘Valerie Finnis’) grows about 24 inches tall and its foliage is ideal dried in wreaths. A. stelleriana (‘Silver brocade’) is a lower growing (1-foot-tall) spreader.
* Bougainvillea. All types thrive in full sun, heat, and well-drained soil with low amounts of supplemental water.
* Ceanothus (California lilac). These spring-blooming California natives come in a variety of sizes, from low spreaders to tall, upright types. They flower in all shades of blue, as well as white. With good 3drainage, they endure sun and heat and survive with little or no supplemental water. When getting these plants established, be sure to let them dry out between waterings. C. gloriosus and various cultivars, and many C. griseus varieties and cultivars make great ground covers.
* Erigeron karvinskianus (Santa Barbara daisy). Trailing plant 10 to 20 inches high that develops white to pink blooms spring into summer and intermittently throughout the year. It can become invasive but is easily controlled. The variety ‘Moerheimii’ is a bit more compact. It will thrive in full sun with low amounts of supplemental water.
* Gaura lindheimeri. Airy, delicate perennial with white or pink flowers and long bloom season. Gaura prefers full sun, well-drained soil; can survive short periods of drought and low amounts of supplemental water but looks best with additional moisture.
* Hardenbergia violacea. A purple flowering vine with a 10- to 12-foot spread. It requires only low amounts of supplemental water once established.
* Helichrysum petiolatum (licorice plant). This is a striking plant to fill in empty spaces. It can reach 4 feet tall and wide.
* Lantana montevidensis. This low-spreading shrub/ground cover grows 12 to 18 inches high and can spread as much as 5 to 10 feet. Numerous varieties are available in an array of colors. Lantana blooms intermittently throughout the year, thrives in a sunny spot and requires only low amounts of supplemental water.
* Lavandula (lavender). Young plants do best with moderate amounts of supplemental water but once established do well with low amounts. There are numerous cultivars to choose from, such as L. dentata (French lavender), which tends to bloom longer than any of the other cultivars. It grows to 2 to 3 feet high with a wide mound.
* Lavatera (tree mallow). Two evergreen shrubs to consider in this species are L. assurgentiflora, an 8- to 12-foot mound with purple blooms spring through fall and intermittently throughout the year, and L. bicolor, the same size or slightly smaller shrub with white blooms and rose-purple centers. These shrubs thrive in full sun and tolerate drought but do best with periodic deep watering in hot inland areas.
* Leonotis leonurus (lion’s tail). An evergreen shrub with deep orange blooms that can reach 6 feet tall and wide. It prefers full sun and requires low amounts of supplemental water in the dry season.
* Leucophyllum frutescens (Texas ranger). This 6- to 8-foot mounding shrub has silver-white leaves and purple blooms. It thrives in hot, dry, sunny spots and can survive extended periods of drought. L. f. compactum grows to only 3 to 4 feet.
* Limonium perezii (Statice perezii; sea lavender). This long-blooming 12- to 18-inch perennial with purple and white blooms tolerates heat and full sun and requires little water once established.
* Oenothera berlandieri (Mexican evening primrose). This rose-pink 12- to 18-inch high perennial thrives in full sun with little water and care once established, but it can be invasive. It makes a great ground cover on hot, dry slopes.
* Phlomis fruticosa (Jerusalem sage). This drought-tolerant perennial forms a 3- to 4-foot-high mound with bright yellow blooms. It thrives in full sun along the coast and requires only low amounts of supplemental water. In really hot, dry areas, consider giving it a bit more water (with summer water it will have a second wave of bloom if cut back after flowering).
* Romneya coulteri (Matilija poppy). This California native has spectacular white blooms up to 9 inches in diameter on a 5- to 8-foot mound, late spring through early summer. It prefers full sun. Withhold summer water to control its invasive underground rhizomes. Tends to die back in late summer.
* Rosemary (Rosmarinus officinalis). These plants will endure heat, drought and poor soils. Use them as background plants, screens or unclipped hedges. Rosemary prefers full sun, well-drained soil and low amounts of supplemental water.
* Salvia (sage). Many plants within this genus require only low amounts of supplemental water and are ideal on hot hillsides. All require good drainage. Several California natives fall in this category, such as S. ‘Allen Chickering’ (3- to 4-feet high and wide) and S. Clevelandii (four feet high and 4 to 5 feet wide). Both prefer full sun and need little or no supplemental water once established.
Salvia chamaedryoides (3 feet tall and wide) has beautiful gray foliage and purple-blue blooms and thrives with low amounts of supplemental water. S. leucantha has striking purple bracts and purple or white blooms and accepts regular watering, as well as short periods of drought.
* Santolina. These plants do best in a sunny, well-drained spot with low amounts of supplemental water. Santolina chamaecyparissus (lavender cotton) has 1- to 2-foot-tall gray foliage that can spread 2 to 3 feet across with bright yellow blooms.
* Stachys byzantina (lamb’s ears). Use this species along border edges or up close in a raised planter where its unique soft, furry foliage can be viewed up close. Once established, it will tolerate heat, short periods of drought and can survive with low amounts of supplemental water. For pure foliage effect, you may wish to consider a cultivar that never blooms, such as ‘Silver Carpet.’
* Tagetes Lemmonii (mountain marigold). This 3- to 5-foot-high perennial can spread into an 8- to 12-foot mound. Blooms appear late fall through winter in shades of yellow-orange. It is adapted to full sun and hot summers with long periods of drought, but does best with periodic deep watering.
* Thymus (Thyme). These perennial herbs and ground covers thrive in sunny, well-drained spots with low amounts of water once established.
* Verbascum. Many verbascums are biennials, blooming the second season, setting seed and then dying. Most self-sow prolifically. V. bombyciferum ‘arctic summer’ sends out 5-foot spikes with light yellow blooms, a striking accent for any garden.
* Verbena. These perennials do best in full sun and well-drained soils with low amounts of supplemental water. (Most types will accept regular watering, which will prolong bloom.) V. rigida, a 10- to 20-inch-tall perennial, has purple-blue blooms summer and fall and needs little water to thrive. V. bonariensis, a 3- to 6-foot-tall airy perennial, requires little water as well.
* Zauschneria (California fuchsia). These California natives tolerate hot, dry conditions and need little or no water once established. Tubular blooms in shades of scarlet, orange-red, white and pink appear from summer into fall. As they can become a bit rangy, they look best in informal gardens or on hillsides.
