Give Roses Light and Air
By now on the East Coast, lots of roses have mildew or black spot on the leaves. Prevention through good cultural conditions -- selecting disease-resistant cultivars and planting where there are 8 hours or more of sunlight and good air circulation -- is the best approach. As this is not the time to move roses, consider removing nearby tree and shrub branches to increase light and air flow.
Use Organic Control for Mildew and Other Diseases
Try an organic control against mildew on roses and perennials, even food crops. Serenade's Bacillus subtilis is a biofungicide for powdery mildew, downy mildew, bacterial spot, rust, and more. It stops plant pathogen spores from germinating and disrupts pathogen growth.
Prune Off Spent Lilac Flowers
Remove dead lilac flower clusters by pruning just above a node (where leaf joins stem). Then remove older or crowded branches with a pruning cut at the base of the shrub. That's right, squat or bend over to reach inside the shrub just above the soil, and clip the branch low. Also prune off crossing or damaged branches. Leave the strong, healthy branch; remove the broken, spindly, or weak one.
Pinch for Bushiness
Pinching off the stem tip on basil, mums, and sweet potato vines will make the plants grow more bushy. In northern climes, pinching or pruning off the summer phlox's stem tip right now also will promote bushy growth without flower loss. Doing it much later, though, will remove flower buds.
Deadhead to Stimulate New Flowers
Pruning to remove dead flower heads from salvia, veronica, lady's mantle, malva, coreopsis, valerian, and perennial geraniums can make way for continued or later flowering. For lady's mantle, coreopsis, and geraniums, individually cut off each dead flower stalk at the base of the stalk. Clip salvia, valerian, and veronica more carefully -- just below the dead flower head. Look carefully and you'll see small flower buds emerging lower on the same stalk.