I find it interesting when people ask me what types of plants are good in hot dry locations; we live on the west coast where it rains an average of 166 days with over 47 inches of rain (Vancouver/Richmond) per year.
This is not a dry climate... however there are times when we do not get the rain and temperatures can hover in the 30's for short periods. What perennials can we grow that will take the rain but also tolerate short periods of hot dry conditions?
True "desert type" plants that will take extended periods of heat and drought do not fare well here unless grown in pots or under special conditions, they include cacti, succulents and those special plants adapted to specific desert-like environs. Many plants that have adapted to these conditions shut down or go dormant which makes them not very appealing to the average west coast gardener. Gardeners want to see their plants thriving, covered in lush growth during the summer months not bare or dormant.
So what can we grow that will give us the best of both worlds? I will divide the plants into two categories, R- those that require dry periods and T- those that will tolerate it.
R - Type Plants
Those perennials that require drier conditions to thrive are a challenge to grow in the lower mainland as we are a temperate rainforest and get far too much rainfall. To grow these plants they will need a very warm, sunny (or part shade) location with excellent drainage to carry away any excess moisture from the root zone.
Placing plants against rock/stone walls or along pathways of similar material affords them additional radiated heat and planting in raised beds or on slopes gives them the extra drainage they need. They should require little in the way of water except of course when they are first planted. Once plants are well established (at least 1 season) they should survive with just natural rainfall or minimal watering.
Hardy Ice Plant
This succulent type perennial comes from South Africa, it forms a low mat of fleshy evergreen leaves. Abundant starry flowers produced atop the plants appear from late spring into fall. Makes an excellent groundcover for hot, dry areas; requires sharp drainage in full sun. Height: 5-10cm Spread: 30-45cm Zone: 5
Also called desert candles these spectacular perennials hail from central and western Asia. Foliage resembles a low clump of soft yucca-like green to blue-green leaves. Tall flowering stems (to 3m+) are topped by bottlebrush flower-spikes that range in colour from white, yellow, peach, orange and pink; early to mid summer. Like many drought tolerant plants they may go completely dormant after flowering. Plants require full sun and prefer sandy soil that is sharply drained as the roots are prone to winter root rot. Height: 1.25-3m Spread: 60cm Zone: 5
T - Type Plants
The second group includes perennials that like our moist climate, especially in the spring where it is needed for new growth and flowering, but will tolerate short periods of dryness, usually during the summer. That being said they will stress during very hot periods and should be watered to maintain health.
Brunnera macrophylla var.
What versatile, bold and elegant perennials these are. Large heart-shaped foliage in a variety of colours and markings make them indispensible in the shade garden or mixed container. Once established they tolerate competition with large plants (see example below) and will even perform quite well through a drier summer. However they do require moisture especially during the peak growing period (spring) and can thrive quite nicely in moister environments. Sapphire blue, pink or white forget-me-not flowers eclipse the emerging growth for several weeks in early spring. Prefers a cool, shady site in humus rich soil but again if plants are established they will tolerate dry periods. Height: 40-50cm Spread: 60cm Zone: 4
Invaluable plants often planted as ground-cover in difficult shady sites and can hold their own amongst larger established plants. Many selections are available with innumerable leaf forms, size and colouring both evergreen and deciduous. Flowers are available to suit almost any fancy and are heralds to the coming spring. It has been noted that they are somewhat deer resistant... however the younger members of what I call "giant 4-legged slugs" always want to taste test, so no plant is really safe. A great low maintenance perennial. Their preference is a shady site in rich well-drained loamy soil. Height/Spread: variable Zone: 4+
Here are some more drought tolerant R Type Perennials:
More T Type Perennials
Art's Nursery carries a large and diverse selection of drought tolerant perennials, plants and shrubs. Please call ahead (604.882.1201) to confirm availability of specific varieties as our stock and selection are always changing.