Your September Garden Checklist: Planting, Prep, and Maintenance

Plant More of Your Favorite Perennials

Set out transplants of campanula, candytuft, catmint, coreopsis, delphinium, dianthus, foxglove, penstemon, phlox, salvia, hollyhocks, and yarrow. In areas with deep winter freezes, spread a thick mulch layer around plants.

Create a Late-Summer Show in Pots

A single pot adds a splash of color by a path; for a patio garden, cluster three pots. Use large containers (at least 18 inches across) and a good potting mix; buy blooming perennials in gallon cans. Before planting, position the container, fill all but the top 6 inches with soil, and mix in slow-release fertilizer. Arrange plants in their nursery pots on the soil—tallest in back or center, lowest at edges. Once satisfied, remove plants from pots, pack them in, firm soil around root balls, and water thoroughly.

Prep and Mulch Planting Beds

Before fall planting, amend vegetable or flower beds with compost or organic mulch. Compost supplies nutrients until spring (in mild winters) and preconditions soil for spring planting (in cold regions). For good loam, dig in a 2- to 3-inch layer; for heavy clay or sandy soil, add twice that amount. A mulch cover (e.g., shredded bark) insulates roots against hard freezes and reduces mud. One cubic yard covers 108 square feet at 3 inches deep; a 2-cubic-foot bag covers 8 square feet at 3 inches deep.

Fertilize the Lawn

Early fall feeding thickens top growth to crowd out weeds and strengthens roots for winter. Combination fertilizers with fast- and slow-release nitrogen are ideal. Apply enough to supply 2 pounds of actual nitrogen per 1,000 square feet. Alternatively, leave grass clippings on the lawn—as they decompose, they release nitrogen. A mulching mower speeds this up and can eliminate one or more feedings per year.

Plant Trees and Shrubs

Fall planting gives shrubs, trees, and groundcovers a head start: nature handles watering, and plants establish roots through fall and winter (in mild climates). Apply several inches of organic mulch around plants (keep away from trunks) and keep roots moist if rainfall is insufficient.

Plant Spring Flower Bulbs Now

Every spring bulb is a complete package for a splendid show. Bulbs appear in nurseries right after Labor Day—plant them immediately. They're most effective in large pots and kidney-shaped drifts at the front of beds. Excellent choices include bluebells, daffodils, grape hyacinth, hyacinth, and tulips.

Grow Your Own Salad

Mesclun mixes (tasty blends of young leaf vegetables) are easy to grow in beds and boxes. Sow seed every few weeks during fall and spring in mild-winter climates, or spring into summer in cold-winter areas, for a long harvest season. In full sun, dig compost into the soil and water thoroughly. Sow seeds 1/2 inch apart, cover with 1/4 inch of fine soil, water lightly, and keep soil evenly moist.