Perennials: As a preventive for fungal disease on roses, spray the plants weekly with a mixture of 1 tablespoon of baking soda and 3 tablespoons of horticultural oil per gallon of water. Removing spent flowers keeps them from producing hips or seeds. When cutting roses for bouquets, cut each rose just above a bud so that at least two five-part leaves remain where the branch joins the main stalk. Avoid overcutting new rose bushes the first year.
Flowers: Honey dew on plant leaves may mean aphids. A strong spray from the hose will remove most of these pests. Most herbs need no fertilizer and little water, so water only during prolonged dry spells. They abhor chemical treatments. Avoid mulching herbs because that keeps the soil too moist and will encourage fungus. If this occurs cut them back to encourage new growth.
Vegetables and fruits: Thin to 10 inches between corn plants and at least 8 inches between bean plants. Check potatoes for potato beetle. Hand pick as soon as they appear. Plant more lettuce. Pick radishes before they grow too large and too hot.Watch carefully for yellow or browned leaves on tomatoes. Remove diseased leaves immediately and repeat treatment as recommended by your county Cornell Cooperative Extension.
Trees and shrubs: Prune dead, diseased wood and water sprouts from dogwoods and magnolias. Prune hedges so that the bottom is broader than the top. This allows sun to reach the lower branches. Continue pruning spring flowering shrubs.
Lawns: Compost grass clippings or just leave them on the lawn as fertilizer. Spot treat weeds in the lawn.
Houseplants: Keep houseplants out of direct sun rays as they spend the summer outdoors.
Susan Henry, master gardener with Cornell Cooperative Extension of Westchester