The recent mild weather makes us feel more inclined to take on strenuous gardening jobs, such as pruning. But is it too late for serious pruning?
For most woody plants, it is either too late or too early to prune. Spring bloomers, including forsythia, azaleas, and most of the hydrangeas, should be pruned from May through July; earlier pruning removes this years flower buds, later pruning cuts off next years, and either will result in fewer flowers. Summer bloomers, such as butterfly bush, vitex, rose of Sharon and clethra, flower on new wood and are pruned January through March to stimulate lush new growth. Evergreens that are grown for their foliage, such as boxwoods and yews, need three months after pruning for the new growth to harden off before the first frost. They are pruned from November through July. So, except to remove damaged or diseased wood, or perhaps the odd errant branch thats an eyesore or obstruction, late summer is not the time for pruning.
Incidentally, woody plants should not be fertilized again before winter as the resulting new growth will not have time to harden off before the first frost.
While many of the heat-loving tender perennials are coming into their own now, including angelonia, begonias, pentas and lantana, some of your garden regulars might be looking tired. Pull up any petunias, lobelia, snapdragons or other annuals that are past their peak and replace them with healthy new specimens in large pots, or choose colorful chrysanthemums or asters in preparation for autumn.
Continue to feed annuals and late-blooming perennials with a diluted liquid fertilizer every two to four weeks to keep them growing strong and flowering well. Organic fertilizers, which attract beneficial micro-organisms to the soil, are the best choice.
Its not too early to be thinking about bulbs, particularly the delightful autumn bloomers. As soon as they appear in the nursery, buy and plant Sternbergia, which looks like a large yellow crocus, autumn-blooming crocuses, which are usually violet, or the late summer-flowering Lycoris, a taller flower with spidery red, yellow, white, or pink blooms. All of these will bloom this year if planted early. Amend the soil with organic matter (manure, leaf mold, bagged compost or soil conditioner will do nicely) and add a tablespoon of bulb food or bone meal to the bottom of the hole. All bulbs prefer regular watering while their leaves are present and an annual feeding with a fertilizer specially formulated for bulbs, such as Bulb Tone. After flowering, leave the foliage to wither naturally before removing.
Unusually mild temperatures can lure us into a false sense that we dont need to water, but even a summer downpour that unleashes an inch of rain in an hour tends to run off the soil surface, leaving the roots thirsty. Deep, slow watering is required to moisten the soil to a depth of six inches, which will stimulate deep root growth and enable plants to withstand drought. Parched plants produce small, sparse blooms and dry, tasteless fruit this year and poor flowering and fruiting next year, so dont neglect your strawberries, raspberries and spring-blooming shrubs. A soaker hose left on for two to three hours twice a week should provide roots with adequate moisture. If youre using a sprinkler, place an empty tuna can in your flower bed and water until there is one inch of water in the can. Plants that are on a hillside, in a hot, south-facing location, or are exposed to drying winds, may require additional watering.
Eileen Powell is a professional gardener and garden writer. Her latest book is The Gardeners A-Z Guide to Growing Flowers from Seed to Bloom.