So. California

What to do in your garden in September
Sharon Cohoon

PLANTING

Landscaping plants. Fall and winter are the primary growing seasons for Mediterranean and native plants ― like ceanothus, coffeeberry, manzanita, rosemary, and toyon ― which are ideally suited to our climate. That's why it's also the best time to plant them. For a list of many other such plants and the retailers who stock them, visit www.thegarden.org and click on "Locate a Local Nursery," then "Nifty 50."

Peas. Edible pod peas, such as sugar and snow peas, taste best when they're cooked immediately after picking. Plant seeds 1 inch deep in well-amended soil, then keep soil damp until seeds germinate. Protect young seedlings from birds with overturned berry baskets. If you don't want to bother with staking, grow one of the bush varieties, such as 'Oregon Sugar Pod II'.

Spring bulbs. Continue to plant South African bulbs ― babiana, freesia, ixia, sparaxis, and watsonia. Wait until next month to plant anemones, daffodils, Dutch irises, and ranunculus. Hyacinths and tulips need at least six weeks of chilling in the refrigerator before planting. In the high desert ( Sunset climate zone 11), however, all spring bulbs should be planted now. Step-by-step: Planting bulbs in pots

Sweet peas. For best performance, plant all varieties of sweet peas this month or next. Your best bets for bloom by the holidays are 'Early Mammoth' and 'Winter Elegance' and the dwarf variety 'Explorer'.

Winter vegetables. Starting midmonth, coastal (zones 22-24) and inland (zones 18-21) gardeners can sow seeds or plant seedlings of beets, broccoli, brussels sprouts, cabbage, carrots, cauliflower, chard, collards, kale, lettuce, green and short-day onions, pak choy, parsnips, potatoes, radishes, spinach, and turnips. In the high desert, plant lettuce, radishes, and spinach. More: Guide to salad gardens

MAINTENANCE

Cut back Matilija poppies. Romneya coulteri is beautiful ― but very rambunctious. To help keep it in bounds and looking good, cut plants back to the ground now. Flowers bloom on new wood, and plants spring back quickly.

Protect against brushfires. In fire-prone areas, before the onset of Santa Ana winds, cut and remove all dead branches and leaves from trees and shrubs, especially those that grow near the house. Clear fallen leaves from rain gutters and remove woody vegetation that is growing against structures.

Shear grasses. Purple fountain grass ( Pennisetum setaceum 'Rubrum') and other warm-season ornamental grasses need cutting back more than once a year to avoid thatch buildup, advises Tom Jesch of Daylily Hill Nursery in Escondido. Cut them back nearly to the ground by mid-September so they'll grow back quickly and look good through winter. Shear them back again in April.

Treat hydrangeas. To keep hydrangea flowers blue, treat the soil around the plants with aluminum sulfate (it needs to be done several months before bloom to be effective). Use 1 tablespoon per foot of plant height or ¼ teaspoon per potted plant. Mix into water and apply as a soil drench. Repeat treatment in late fall and again in early spring.

More great ideas for your September garden