Northern California Coastal & Inland Valleys
Keep Deadheading Agapanthus
As the agapanthus flower fade, remove them to improve the plant's looks and maybe stimulate more flowers to form. These hardy plants have been known to send up a second flower stalk. Cut the flower stems at the base, near the foliage, but leave any healthy leaves.
Rake Garden Beds
Rake and clean garden beds that have finished producing to remove fallen foliage and debris. Slugs, insects, and fungus spores prefer trashy gardens to clean ones. By removing their favored hiding places, you reduce the amount of insect damage and disease in your garden for the coming crops.
Prune and Fertilize Rhododendrons
The end of August is the last chance to safely prune and shape your rhododendrons and azaleas. After this period they'll be forming flower buds for next spring, so don't prune. Fertilize the plants with a high-acid fertilizer after pruning to encourage maximum bloom.
Mulch around the base of ornamental maple trees to conserve moisture and help keep the leaf color bright. Some maples, such as Acer japonica 'Burgundy Lace' will lose foliage color if reflected heat from nearby driveways and sidewalks is too hot. Mulching the surface of the soil under the plants keeps the ground cool and prevents colors from fading. Keep the layer of mulch a few inches from the base of the trunk to avoid fungus problems.
Start Seeds for Winter Annuals
Start seeds now for your winter annual flower garden. Pansies, calendula, ornamental kale, and stock can be started from seed for planting into the garden in October and early November while the soil is still warm. Planting from seed is much less expensive than buying transplants, and you'll have a much larger selection of varieties to choose from.