What to do in your garden in September

PLANTING

Cool-season flowers. Set out seedlings of flowering cabbageand kale, pansies, and violas.

Cool-season veggies. Sunset climate zones 4-7, 17: As soon as possible, sow seedsof arugula, leaf lettuce, mustard greens, and radishes for fallharvest. Set out nursery-grown seedlings of these, plus cabbage,kale, purple-sprouting broccoli, and spinach. More:Guide to salad gardens

Cover crops. As you remove annual veggies, sow seeds ofcover crops like Austrian field peas, crimson clover, and vetch.During the winter, these plants will reduce soil erosion from windand rain. Next spring, you simply till them under to improve thesoil’s organic content and texture. A good source for cover cropsis Territorial Seed Company(800/626-0866).

Landscape plants. Autumn is the best time to set out trees,shrubs, vines, groundcovers, and perennials. Buy them in containersat the nursery (or ask neighbors for divisions of perennials).Plant right away and water thoroughly. Rainfall and cooltemperatures will encourage plants to develop strong roots overwinter so they’ll be well established for the next growingseason.

Lawns. Zones 1-3: Start lawns from seed anytime throughmid-September; lay sod through mid-October. Zones 4-7, 17: Sowgrass seed or lay sod anytime this month. Consider replacing thinor worn patches of turf with drought-tolerant groundcovers orgravel pathways. More:Fall lawn care

Spring-blooming bulbs. Shop catalogs and nurseries forbulbs; get them into the ground soon. For long-term performance,choose among bluebells, camass, crocus, daffodils, fritillary,grape hyacinths, snowdrops, species tulips, and star of Bethlehem.Hyacinths and standard tulips remain viable for two or three years.Step-by-step:Planting bulbs in pots

MAINTENANCE

Rose care. After the fall flush of bloom, don’t deadheadfaded blossoms; leave them to form fruits, called hips. This helpsroses transition to winter.

Control fungus gnats. These small, dark-winged insects flitaround houseplants and breed in the potting soil. To stop them,cover the soil with a layer of sand (if you have cats, usegravel).

Divide perennials. Now’s the time to dig up, divide, andreplant spring- and summer-flowering perennials, including orientalpoppies, peonies, Shasta daisies, and Siberian irises. Divide fallbloomers after flowering or wait until new growth starts inspring.

Make compost. As you remove spent flowers and vegetables,toss them on the compost pile. But don’t add diseased plants orweeds that have gone to seed. Step-by-step:Make your own compost bin

Get more seasonal tips and ideas on our Garden page