Summers here in the Piedmont can be brutal, with scorching temperatures and scarce rainfall. Keeping plants alive often means using drinking water to irrigate, which is expensive and a waste of precious resources.
To demonstrate that you can have a beautiful garden with little to no watering by following a few guidelines, the Extension Master Gardener Volunteers of Wake County created and maintain two “Waterwise Gardens.” One is located at Lake Crabtree and the other is at the State Fairgrounds. These gardens have been in place for a number of years and survive on little to no added water.
The first guideline is thorough soil preparation, which is no surprise. But for real drought tolerance, you can’t just dig a hole for the plant and walk away. It takes a jackhammer to break that clay, so you know tender roots can’t do it. For all herbaceous and woody plants, preparing the entire bed will give you long-lasting benefits in terms of plant resilience. This means digging or rototilling 8-12 inches deep. If there is a hard clay layer below that, try cracking it with a pitch fork so water and roots can penetrate. Pick a cool fall or spring day to do this work when the soil is soft from significant rainfall. It’s a huge piece of work, but it’s an investment that pays for years to come.
Mix in 1-3 inches of compost or other organic material like leaf mold, and then conduct a soil test, a free service at the NCDA Agronomic Division from April-November (fee charged in other months). The soil test tells you if you need lime to raise the pH level, and if you need fertilizer nutrients. Remember, nitrogen may be applied each year, but lime and other fertilizers should only be put on if recommended. Adding fertilizer to dry plants will only stress them more. It’s like serving salty chips to a dusty desert wanderer. Well-established perennials and woody plants require few amendments, so test your soil.
The second guideline is choosing plants that will thrive in your location. Is it full sun, part sun, part shade or shady? Is the soil dry or does it tend to stay wet? These are crucial questions. We want plants that are at their happiest in the correct situation so finding the “sweet spot” for your plant cannot be overemphasized.
For a waterwise garden, you want plants that either thrive in or tolerate hot, dry conditions. Many of our natives are well suited to our climate, but many other non-natives do just fine here as well. Even some annuals will take a dry heat beating, like cosmos, marigolds, portulaca, cleomes, and others. Ask your local nursery or garden center if a plant you like fits your site and can make it through summer without irrigation once established.
Mulching is the third important piece for efficient water management. Placing a 2-4 inch layer of leaf, pine or hardwood mulch on the garden will keep water from evaporating from the soil, keep the soil cooler in the heat of summer, and prevent weeds from germinating. Apply the mulch each spring once the plants have emerged. A second mulching later in the season can really help keep weeds down and conserve soil moisture through the fall. Think of it as a “cooling blanket” that your plants will adore.
Visit the Waterwise gardens at Lake Crabtree County Park in Morrisville (open 8am–sunset) and the State Fairgrounds in Raleigh (open 9am-5pm) to gather ideas for tough performers. The Fairgrounds garden is oriented towards fall bloomers for the State Fair, so stop by in October for the best blooms.
Here are some favorite plants of Master Gardeners Trish MacPherson, Kristen Monahan and Cindy Chappell who oversee the Waterwise gardens.
Achillea millefolium (purple yarrow)
Artemisia schmidtiana ‘Silver Mound’
Aster novae-angliae ‘Purple dome’
Baptisia australis (wild indigo)
Berberis thunbergii (Barberry ‘Rosy Glow’)
Buddleia lindleyana (butterfly bush)
Canna musafolia (banana leaf canna)
Echinacea purpurea ‘Kim’s Knee High’
Eryngium venustum (sea holly)
Foeniculum vulgare (fennel)
Kalimeris pinnatifida (Japanese aster)
Miscanthus sinensis (maidenhair grass)
Phlox subulata (creeping phlox)
Salvias – many species
Stokesia laevis (Stokes’ aster)
Thymus serpyllum (creeping thyme)
Yucca ‘Gloriosa’ (variegated yucca)
Featured photo – Waterwise Garden / by Jeana Myers
Jeana Myers, PhD, is the Horticulture Agent for Wake County. For gardening questions, contact the Extension Master Gardeners of Wake County at 919-250-1084 or email firstname.lastname@example.org.