Perennials: Continue planting and transplanting perennials, adding a trowel full of compost to each newly dug hole. Thin the stems of late blooming phlox and asters to the ground for larger flowers and fewer mildew problems later. Pinch back other late blooming perennials. Monitor roses for black spot and keep up with regular rose feeding and spray program.
Flowers: Plant summer annuals in among perennials and in containers — now is the time to be creative. Nicotiana, verbena, salvia and ageratum all give lovely color variety. Cut back annuals by as much as half when planting to reduce stress through water loss and to produce better branching and flowering. Fertilize with liquid fertilizer, measuring according to directions, shortly after planting. Zinnia, cosmos and nasturtium can go directly into the garden. Set out dahlia tubers.
Vegetables and fruits: If the soil temperature is above 65 degrees, plant sweet corn now in blocks of four rows or more to ensure good pollination. Continue thinning root crops, weeding, mulching and watering as needed. Resow lettuce, carrots, spinach and beets for young crops. If there is an overabundance of produce, plant half rows and more varieties. Organic seeds, certified free of pesticide treatment, are now widely available. Remove flower stalks from rhubarb. Rhubarb can be cut into short pieces and frozen raw for later use. Sow basil and dill and cilantro. Place marigold plants near tomatoes for protection from pests.
Trees and shrubs: Deutzias, forsythias, and weigelas benefit from annual or biennial pruning shortly after flowering. Wait to prune hedges until July. Continue a regular schedule of the application of deer repellents. Fertilize needle evergreens with acid type fertilizer and mulch other ericaceous ornamentals with high acid mulch. Monitor for chewing insects and treat accordingly.
Lawns: Finish lawn fertilizing by the end of the month, and reseed bare spots, watering afterward.
Houseplants: As night temperatures moderate into the 60s move houseplants outdoors, avoiding full sun and windy locations. Repot as needed.
General: Be vigilant about pulling out destroying wild garlic mustard, a biennial invasive weed with bright green leaves and small while blossoms.
TJN file photo
If pulled before it flowers it is less likely to return.
— Susan Henry, master gardener with Cornell Cooperative Extension of Westchester