Avoid Overfertilizing Plants
When it comes to fertilizers, more isn't necessarily better. Too strong a solution of synthetic fertilizer can harm plant roots. And high-nitrogen fertilizers can promote leafy growth at the expense of flowers and fruit. Healthy soil that has been amended with compost can support most plants; an occasional side-dressing or feeding with an organic fertilizer can boost growth and improve yields. Follow label directions for application and dilution rates.
If nature doesn't provide a good weekly soaking, water plants thoroughly. Make sure the entire root zone is moist, then wait to water again until the soil begins to dry. Frequent light sprinklings promote shallow, drought-sensitive root systems. Use soaker hoses to apply a slow, steady supply of water directly to the root zone.
Lightweight potting soil can dry out quickly in containers. Apply a 2- to 3-inch-deep layer of shredded bark mulch in containers, keeping mulch an inch or so away from stems. When watering, make sure the soil is moistened all the way to the bottom. Let excess drain away and empty saucers. If soil dries out completely, it may shrink away from the sides of the pot. If this happens, place the container in a basin of warm water until the soil moistens and fills the pot, then allow to drain.
Attract Beneficial Insects
Grow plants that attract beneficial insects, such as honeybees, predatory (nonstinging) wasps, ladybugs, and lacewings. Plants with tiny flowers and those with umbel-shaped flower clusters are especially attractive to beneficials. Examples include alyssum, chamomile, dill, fennel, oregano, rosemary, thyme, and yarrow.
Remove Diseased Rose Leaves
Visit your roses as often as possible, and not only to enjoy their fragrant blooms. Take a pair of scissors or small pruners and remove leaves showing signs of black spot, a common fungal disease of roses. Look for leaves with dark splotches with irregular edges, remove them, and throw in the trash rather than the compost pile to avoid infecting other roses.