Caring for the Summer Garden
From watering to pruning, many gardeners are at a loss about the best way to care for their garden during the dog days of summer. This Q&A session answers gardener’s most common summer care questions.
Q: What is the best way to keep shrubs watered during extreme heat and drought?
A: Water deeply. The best way to water any time of year is applying water slowly for a long enough duration to moisten soils to a depth of 12 inches. Applying the water slowly allows water to permeate into the soil rather than running off across the soil surface. Deep watering encourages deep rooting, while shallow watering promotes shallow roots that grow in hot, dry surface soils. The rule of thumb is to apply one inch of water in a single application each week, however during extreme heat sensitive plants will require more frequent irrigation.
Q: I water my garden every day, why are the plants wilting?
A: Over-watering plants can result in the same symptoms as under watering. Saturated soils lack oxygen needed by the roots and can cause roots to suffocate. Over-watered plants are also prone to developing root disease. The result is poor uptake of water that causes plants to wilt. Reduce irrigation. Water plants only when the soil feels dry to the touch at a depth of one inch and follow deep watering methods. You can also use a water meter to test soil moisture. If wilting plants are in containers, make sure the pots have drainage holes.
Q: Can I prune plants in late summer?
A: Most trees and shrubs should NOT be pruned in late summer. Pruning encourages new growth that may not have time to harden properly before cold temperatures arrive. Of course, there are exceptions to every rule: July and August are the months to prune azalea, dogwood, forsythia, redbud and rhododendron. These plants are pruned after they bloom, but before new flower buds are set in fall. Also, it is appropriate to remove damaged, diseased and dead plant materials any time of year.
Q: Where have all the birds gone?
A: Many songbirds molt in late summer, shedding their feathers to grow a fresh set. As birds are vulnerable during molting, their activity is low, leaving feeders quiet. But hummingbirds are starting their southward migration and numbers will begin to soar. Keep hummingbird feeders well stocked and offer nectar-rich plants to fuel the migration. Try these hummingbird favorites: ‘Amistad’ Salvia, Bells of Fire™ Tecoma and Stars & Stripes™ Pentas.
Q: I know roses benefit from deadheading, what other shrubs do too?
A: Deadheading, the removal of spent flowers, promotes plants to produce new blooms. Most annuals benefit from deadheading throughout the entire growing season, however many new varieties are “self-cleaning” and need no clean-up. Flowering shrubs like Ultra Violet™ Buddleia and Little Bonnie™ Dwarf Spiraea benefit from deadheading, as do perennials including ‘Celebration’ Gaillardia, Lydia™ Tecoma and Dark Blue Moody Blues™ Veronica. For roses and other woody plants, deadheading should be stopped mid-August to help initiate winter hardiness.
Q: The leaves of my hollies are covered with dull speckles.
A: You likely have spider mites—tiny insects erupt when temperatures soar. Commonly attacked shrubs including arborvitae, azalea, camellia, hollies, ligustrum, pittosporum, pyracantha, rose and viburnum. To detect spider mites, hold a sheet of paper beneath infected foliage and tap branches; mites appear as tiny spots moving across the paper. You may also notice webbing among branches. Water-stressed plants are more susceptible to mites, so keep plants well irrigated during dry spells. Dusty conditions also promote infestations—water paths occasionally to keep dust down and wash coated plants with water. Insecticidal soaps and oils are effective against mites or a hard stream of water can be used to wash mites from plants.
Q: My plants look stressed, should I fertilize?
A: Heat- and water-stressed may look like they could use a boost from fertilizer, but trees, shrubs, turf and perennials should not be fertilized during times of drought. Fertilizer can cause root injury when soil moisture is limited. Late summer fertilizer applications also encourage new growth that does not have time to harden before the onset of winter. With the exception of flowering annuals and vegetables, you can put the fertilizer away during late summer.
Q: How can I maintain my lawn during drought and water restrictions?
A: Do not fret if water restrictions prevent you from irrigating lawns. Warm-season grasses including centipedegrass, bermudagrass, zoysiagrass and St. Augustine grass naturally enter dormancy during periods of high heat and water stress. Alter maintenance practices accordingly—mow less often and raise the height of the mower blade. These grasses can survive drought in a dormant state and rebound after rainfall returns. Cool-season turfgrasses are less tolerant of drought. To maintain cool-season lawns during drought slowly apply one inch of water during the early morning hours. Irrigate only when lawns are dry, do not use “scheduled” irrigation.