Temperature, sunshine and moisture dictate how healthy daylilies, roses, dahlias and other repeat-blooming perennials will do. Cut the flowering scapes of daylilies at the base after all flowers on a stalk have faded. Certain hybrids like Stella d’oro will rebloom.
Hybrid tea roses are also bred to repeat bloom. They can be coaxed into forming new flower buds provided flowers are pruned before they drop their petals. Cut the stem of fading roses back to a healthy leaf containing at least five leaflets. You can keep tea roses blooming all summer this way.
Dahlias will offer a long season of flowers beginning about June in the D.C. region. Once they begin to flower, they generally will continue to produce blossoms until first frost.
These plants create excellent color throughout summer, but deer love all three and you may need regular applications of repellent or fencing for protection. Our Stellas haven’t been browsed, so these might be somewhat more resistant than other daylilies.
Deadheading fading flowers can help most plants. This is the time to shear faded flowers (flower spikes only) of perennial candytuft (Iberis sempervirens). They will come back denser next spring. Clip flowering stems of faded dianthus. Cut iris stalks to the base after they have fully bloomed, leaving foliage. There are repeat-blooming bearded irises in almost every color. Deer do not choose them unless they are starving.
Deadhead rhododendrons where the flower meets the stem, being careful not to break off vegetative buds below the fading flower. That’s where new growth is produced. Rhododendrons are not favored by deer.
Deadheading annuals will encourage new flowers as the old ones fade, especially petunias and geraniums. Pinch or cut the flowering stem or just the fading flower if there is foliage on the stem. Many perennials are making or preparing to make their show, including shasta daisy, liatris, penstemon, salvia and astilbe. While doing your June deadheading, clip some freshly opening flowers and bring them indoors for flower arrangements, stretching your period of enjoyment. Seed heads, like those on astilbe, dry on the plant and are ornamental for indoor use in dry flower arrangements.
Pinch off the top 2 to 4 inches of growth on hardy chrysanthemums now and then two more times by the end of July for fuller plants at blooming time. Fertilize now and again next month with a granular 5-10-5 fertilizer sprinkled around each plant. Leave them in the ground with a little mulch around them through winter, and they will bloom next year.
Dahlias, mums, roses, camellias and hardy gardenia are some other plants that benefit from the protection of winter mulch. Ornamentally mulch in spring to a depth of about 1 to 1 ½ inches. In winter, you can cover the plants with mulch for protection, but this mulch must be removed before growth begins in spring.
Root-prune trees and shrubs now that you might want to transplant in fall. It’s an important part of ensuring a successful transplant. Sink a long, square-edged digging spade into the soil in an 18- to 24-inch diameter circle around the trunk, or wider, depending on the size of the plant. Make sure you slice all the way around. Do not move the plant; allow it to grow more roots at the cut. Dig outside that line when moving in late fall or next spring before growth begins.
Touch up azaleas that have fading flowers, but never cut hard at this time of year. Leave at least two-thirds of a plant’s greenery.
Evergreen hedges might require shearing. Do this no more than once a year, usually after flowering. If a hedge has no flowering value, shear it after new growth has become somewhat woody, during the summer. Do not shear coniferous hedges of pines, spruces, cedars or firs. Locate these where they can grow without needing to be pruned into a hedge.
Prune dead wood as it appears on trees or shrubs to help stave off disease problems. If you are pruning dead or diseased wood, be sure to clean your pruner with bleach and then use a coating of light oil to protect the blades from corrosion before cutting healthy wood.
One of the most common questions I am asked is what type of mulch should be used on landscaped beds. My first response is always “organic material in the form of compost, spread about two inches thick and incorporated as deeply into the bed as possible.” Organic material is the most difficult substance to keep in the soil because it’s the one component that’s continually being reduced by living organisms. Make your own compost and lay it into your planting beds.
People ask what’s the most aesthetically pleasing mulch. My answer is two inches of compost with about a one-inch veneer of aged, double-shredded hardwood or pine bark. This way you get multiple benefits, including nutrient production, moisture retention, soil conditioning, weed control and aesthetic appeal.
I am often asked about the best time to mulch. If you are mulching for aesthetics, spread the ornamental mulch about a week or two before Memorial Day. April showers, flowers and maple seeds have fallen, and the decorative value will be effective for a longer time. Only use ornamental mulch in spring.
Mulching in fall is done for winter protection, not aesthetics. Spread mulch composed of well-aged compost, manure and/or straw.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md.