Hot and Dry Perennials.†
I have had two requests recently for plants that are suitable for hot, sunny, and somewhat dry sites.† The hot and sunny comes from interior courtyards with no plants and extra paving.† The dry comes from no irrigation other than sporadic hand watering by volunteers.††
Common perennial plants that come to mind include cone flower, gallardia, coreopsis, rubeckia, sedums, euphorbia, and yarrow.† I think of them because they are native to the Midwestern United States which has a hot sunny and dry climate.† †Herbs that tolerate hot sunny and dry sites include rosemary, sage, thyme and lavender. †These hail from the Mediterranean Sea area which is also hot sunny and dry. †Then there are spring flowering bulbs.† Bulbs avoid the heat by coming up in early spring and then going dormant during the hottest and driest time of the year.† Crocus from southern Europe and tulips from Turkey come to mind.† Mexico has its share of hot, dry and sunny places.†† Mexican heather and Mexican sunflower perform in hot and dry conditions. Then there is Candor.†† This is a little town on a sandy hill about 70 miles east of Cabarrus County.†† It actually gets more rain than Cabarrus County.† This is because the sand heats up hotter than the clay and fires up more thunderstorms.†† It is still dusty and dry because this extra rain drains away in minutes.†† Other than cactus, gardeners in that area have great results with portulaca.† This is an annual that prefers sand over clay, but in an amended flower bed or in container media it will do fine. The plants I have mentioned so far will get by with no irrigation most years.†
Common annual plants for hot and dry sites include cosmos, sunflowers and zinnias.†† I have grown enough cosmos to know it tolerates hot and dry conditions.† These annuals will perform better with irrigation but generally live without it.
Whitish pubescent leaves often indicate a plant that will tolerate hot dry conditions.† The white color reflects the heat, while the hairs shade the leaf surface.†† Plants like artemisia, lambs ear, lychnis (also known as rose campion,) and buddelija come to mind.† Lychnis doesnít live very long but self sows readily.†† Some of the mulleins have similar heat tolerance.† A plant that isnít very well known is venidium.† I knew nothing about it when I bought it beyond the flower color which I liked, and the whitish pubescence which told me it should tolerate hot dry conditions.†† I planted it in a raised container with hot dry conditions and it bloomed all summer with no additional water.††
Buddelija is actually a woody perennial but it is generally planted with other herbaceous plants and cut back almost to the ground each year.†† †A few other woody ornamentals you might find useful in a hot and dry flower bed or large container include santolina, yucca and Scottish broom.† The shrub forms of St Johnís wort are woody ornamentals for hot and dry conditions.† I donít remember seeing any of these in local nurseries but often see some species in nature.††
The sundrops and evening primrose tolerate hot dry conditions.†† I have had good luck with scaevola.†
I recently saw angelonia in a hot and what I suspect was a relatively dry situation.† Red Hot Poker (Kniphofia) also prefers a hot and dry site.† Wet soggy soils in mid winter will cause a root rot that kills it.††
My mom has a good crop of verbena in what amounts to a rock garden.† She didnít set out to have a rock garden. When we were kids we hauled off rocks by the wagon load when we had a wagon and hauled them off with homemade sleds when we didnít have a wagon.† We created a wall 3 feet high, two foot wide and twenty two foot long with rocks from the vegetable garden. Anyway, we grew up and moved away before Mom ran out of rocks.† So she grows verbena in some of the dry shallow rocky soil that is left. She also grows iris and daylilies in nearby sites.† They would probably do better with more moisture, but will take the drought.†
Some of the best lantanas I have ever seen had been abandoned for a year on a south facing slope.† No water, no fertilizer and no care but plenty of blooms.†† †
I havenít mentioned grasses yet.† Pampas, pennstemon, pink muhley grass and miscanthus are all drought tolerant.††
Searching the literature for a few more candidates I found candytuft, and helianthemum (aka sun rose) are suggested for full sun and dry conditions. Globe thistle is listed for dry sandy conditions.† It would do fine in a container but evidently doesnít like clay soils.† Globe thistle reminded me of Nigellia.† Nigelliaís leaf structure certainly looks like it would tolerate hot conditions. This is based on comparing the amount of edge versus the amount of blade.† This isnít a real good rule of thumb and doesnít tell you about drought tolerance.†† I could never confirm its drought tolerance in the literature I searched, but wouldnít hesitate to include it in a hot and dry garden.† †
For the characteristics of several perennials you might take a look at this website.† http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/perennials/perennial_table.html
That list should keep a gardener busy for a while.
Article was written by David Goforth Agriculture Extension agent North Carolina Cooperative Extension Cabarrus County Center.† Visit my homepage http://cabarrus.ces.ncsu.edu/ or http://cabarrus.ces.ncsu.edu/index.php?page=lawngarden or my blog http://gardeninggurugoforth.blogspot.com/
Contact me at David_Goforth@ncsu.edu.† Reviewed 2007.†