Late-Summer Rose Care
Fertilize and renew mulch on roses now to keep them blooming well into the fall. This will also protect them from drying out if hot weather persists. Use a fertilizer high in phosphorous, such as 15-30-15, to promote blooms rather than foliage.
Practice Good Garden Sanitation
When your veggie beds have finished producing, rake and clean them to remove spent foliage and other debris. Slugs, bugs, and disease pathogens prefer unkempt gardens to clean ones. By removing their favorite hiding places, you'll reduce the amount of insect damage and disease in your garden for the coming crops.
When you've finished harvesting vegetables and it's time to remove the plants, be sure to add them to the compost pile, along with your grass clippings. Keep the pile turned and aerated. If kept moist and well-tended, it will produce more great compost for the garden this fall.
Prune Flowering Shrubs
After flowers are spent, prune back summer-blooming shrubs such as escallonia and viburnum. Pruning too late in the summer will remove future flower buds and encourage stem growth that won't have time to harden before the weather turns cold. As you're reducing the height of tall shrubs and removing errant branches, be sure to thin excessive growth in the center of the shrubs. This will allow sunlight to penetrate deep into the shrub, encouraging the formation of additional flowering branches.
When hydrangea blooms begin to fade from sky blue to a grayish lavender, it's time to cut them back and reshape the shrub. Bigleaf hydrangea (Hydrangea macrophylla) blooms on new stems that grow from old wood, so prune back only the shoots that have produced flowers. To reduce the height of the shrub, cut some of the older wood back, leaving a few buds on each stem. Next year's flowering shoots will develop from these buds.