One year ago, we had the coolest July since 1918. Two years ago, we had murderous heat and drought. The odds favor heat and drought in the Washington area — if not in July, then in August. Gardeners must prepare to save their plants.
Watering is essential, of course. Give priority to the newest plants, those you planted this spring whose roots have yet to become established. Also of priority would be the most valuable plants you have installed over the past few years, particularly the young trees and shrubs in which you made the greatest investment.
Don’t worry about watering the lawn. To stay green, turf grass needs five times more water than other plants. If you just planted new grass, it probably doesn’t have a prayer anyway. Replant it in the fall. If your grass is established, it will survive over a hot summer without your watering it. It will go dormant, and the color will fade to brown, but it will come back.
Other plants you don’t have to worry about are those that tend to be drought-resistant or water-efficient once they are established. There is a long list of these, and if you limit your choices to them — or mostly to them — when you are designing your gardens, it will make life a whole lot easier when the summer heat and drought roll around.
Keep in mind, however, that each plant has characteristics beyond its need for water. Obviously, some need sun to thrive, and others like shade. Some like acid soil, and others don’t. Some will be eaten by deer. Some are invasive. The crape myrtle, once established, will flower cheerfully through a hot, dry summer with scant rain but a bitter winter could do it in if it’s not in a sunny, protected location.
Read the tag before you buy a plant to be certain it is appropriate for the spot where you plan to install it. Also plan to water a newly installed plant generously once or twice a week its first season or two if there is no rain.
Drought-tolerant woody plants used widely in the Washington area include oak, redbud, ginkgo, hawthorn and golden-rain trees, flowering cherries and pears, juniper, boxwood, hollies, barberry, laurel, aucuba, leatherleaf mahonia, nandina, viburnum, butterfly bush, abelia, lilac and spirea.
To get a good idea what woody plants survive drought after drought with no watering, look at the plants installed along the roads in the county or city where you live. An oak on the cul-de-sac where I live was killed one winter when a load of salt was dumped on it as snow was being cleared from the street. Montgomery County sent a crew to remove it, another to grind out the stump and, two years later, a third to plant a new tree.
The new tree is a red maple. We were not notified when this tree was installed, and as far as we know, the county never came back to water it. The county apparently assumed the tree would be fine. My neighbor who lives closest to the circle didn’t make that assumption. He has a hose that reaches the cul-de-sac, and he watered the new tree during its first hot summer. It’s about 3 years old now and thriving in all but total neglect.
The list of perennials and annuals that are drought-tolerant or water-efficient offers a wide choice.
Perennials include aster, sedum, black-eyed Susan, coneflowers, coral bells, coreopsis, dianthus, hollyhock, hibiscus, iris, lavender, Lenten rose, liatris, ligularia, yarrow, Joe Pye weed, hosta, phlox, pulmonaria, spiderwort, day lily, rosemary, santolina, thyme, blue fescue and most ornamental grasses.
Ground covers include bearberry, plumbago, hypericum, lily of the valley, liriope, pachysandra, epimedium, lamium and lamiastrum.
Though July is late to plant annuals, it also is the time to get them at rock-bottom sale prices. Water-efficient ones include geranium, begonia, marigold, petunias, portulaca, salvia, nicotiana, dusty miller, coleus and annual vinca.
A few tips from the University of Maryland Cooperative Extension Service on helping your plants survive a cruel summer:
Water around the base of plants slowly and deeply at least once a week rather than giving the plants frequent shallow waterings. The soil should be moistened four to six inches deep, depending on the size of the plant.
Use soaker hoses rather than sprinklers to minimize evaporation and waste of water.
Water in the coolest part of the day, preferably in early morning, to minimize evaporation.
Mulch about two inches deep around plants to keep down the weeds, which compete with the plants for water, and to help the soil retain moisture.
Avoid using fertilizers and pesticides during a drought because fertilizer can damage a plant’s root system and pesticides can damage its foliage.
Keep turf grass at least two feet away from the trunks of newly planted or young trees because it competes with the trees for water. Place mulch around a tree instead.