What to do in your garden in September
Landscaping plants. Fall and winter are the primary growingseasons for Mediterranean and native plants ― like ceanothus,coffeeberry, manzanita, rosemary, and toyon ― which areideally suited to our climate. That's why it's also the best timeto plant them. For a list of many other such plants and theretailers 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, tastebest when they're cooked immediately after picking. Plant seeds 1inch deep in well-amended soil, then keep soil damp until seedsgerminate. Protect young seedlings from birds with overturned berrybaskets. If you don't want to bother with staking, grow one of thebush varieties, such as 'Oregon Sugar Pod II'.
Spring bulbs. Continue to plant South African bulbs ―babiana, freesia, ixia, sparaxis, and watsonia. Wait until nextmonth to plant anemones, daffodils, Dutch irises, and ranunculus.Hyacinths and tulips need at least six weeks of chilling in therefrigerator before planting. In the high desert ( Sunset climate zone 11), however, all spring bulbs should beplanted now. Step-by-step:Planting bulbs in pots
Sweet peas. For best performance, plant all varieties ofsweet peas this month or next. Your best bets for bloom by theholidays are 'Early Mammoth' and 'Winter Elegance' and the dwarfvariety 'Explorer'.
Winter vegetables. Starting midmonth, coastal (zones 22-24)and inland (zones 18-21) gardeners can sow seeds or plant seedlingsof beets, broccoli, brussels sprouts, cabbage, carrots,cauliflower, chard, collards, kale, lettuce, green and short-dayonions, pak choy, parsnips, potatoes, radishes, spinach, andturnips. In the high desert, plant lettuce, radishes, and spinach. More:Guide to salad gardens
Cut back Matilija poppies. Romneya coulteri is beautiful ― but very rambunctious.To help keep it in bounds and looking good, cut plants back to theground now. Flowers bloom on new wood, and plants spring backquickly.
Protect against brushfires. In fire-prone areas, before theonset of Santa Ana winds, cut and remove all dead branches andleaves from trees and shrubs, especially those that grow near thehouse. Clear fallen leaves from rain gutters and remove woodyvegetation that is growing against structures.
Shear grasses. Purple fountain grass ( Pennisetum setaceum 'Rubrum') and other warm-seasonornamental grasses need cutting back more than once a year to avoidthatch buildup, advises Tom Jesch of Daylily Hill Nursery inEscondido. Cut them back nearly to the ground by mid-September sothey'll grow back quickly and look good through winter. Shear themback again in April.
Treat hydrangeas. To keep hydrangea flowers blue, treat thesoil around the plants with aluminum sulfate (it needs to be doneseveral months before bloom to be effective). Use 1 tablespoon perfoot of plant height or ¼ teaspoon per potted plant. Mix intowater and apply as a soil drench. Repeat treatment in late fall andagain in early spring.