Your September checklist
What to do in your garden this month
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 where soil freezes deeply every winter, spread a thick layer of mulch around plants.
Create a late-summer show in pots
A single pot can add a splash of color by a path or, for a garden on a patio, cluster three pots together. Use large containers -- at least 18 inches across -- and a good potting mix; buy blooming perennials in gallon cans.
Before planting, put the container where you'll display it, fill all but the top 6 inches with soil, and mix in slow-release fertilizer. Then arrange the plants, still in their nursery containers, atop the soil, with the tallest ones in the back or center, lowest ones around the edges.
When you have an arrangement you like, take the plants out of their pots and pack them in, filling in around root balls with additional soil; firm the soil with your hands and water thoroughly.
Prep and mulch planting beds
Before you plant vegetable or flower beds this fall, your soil could probably use some additional compost or organic mulch.
Compost supplies enough nutrients to carry crops until spring (in mild-winter areas), and preconditions soil for spring planting (in cold-winter regions).
If the soil is already good loam, dig in a 2- to 3-inch layer. For heavy clay or very sandy soil, add twice that amount.
A covering of mulch, such as shredded bark, insulates plant roots against hard freezes and holds down mud. One cubic yard (27 cubic feet) covers 108 square feet with a layer about 3 inches deep. A 2-cubic-foot bag covers 8 square feet 3 inches deep.
Fertilize the lawn
Early fall feeding thickens top growth to crowd out weeds and strengthens grass roots for winter.
Combination lawn fertilizers are a good choice. They contain a small amount of fast-release nitrogen for a quick green-up, and a larger portion of slow-release nitrogen. Apply enough to supply two pounds actual nitrogen for each 1000 square feet of lawn.
Another way to fertilize is by leaving your grass clippings on the lawn. As the clippings decompose, they release nitrogen into the turf. Cutting grass with a mulching mower, which chops the blades into finer pieces, speeds up the process. By doing this regularly, you can eliminate one lawn feeding or more per year.
Plant trees and shrubs
Shrubs, trees, and groundcovers get a head start when planted in fall: nature does most of the watering for you, and plants have fall (and winter in mild climates) to send out roots. Your plants will be well established by the time spring growth starts.
Apply several inches of organic mulch around the plants (don't let it touch the trunks) and keep roots moist if rainfall doesn't do it for you.
Plant spring flower bulbs now
Every spring bulb is a perfect package, containing everything necessary for a splendid spring flower show.
Bulbs appear in nurseries right after labor day. Plant them right away. They're most effective in big flower pots, and in kidney-shaped drifts at the front of garden beds. Some excellent choices include bluebells, daffodils, grape hyacinth, hyacinth, and tulips.
Grow your own salad
Tasty blends of young leaf vegetables called mesclun mixes are easy to grow in beds and boxes. By sowing seed every few weeks during fall and spring in mild-winter climates, or spring into summer in cold-winter climates, you can harvest fresh salad greens over a long season.
In an area that gets full sun, dig compost into the soil; water the bed thoroughly. Sow seeds 1/2 inch apart. Cover the seed with 1/4 inch of fine soil.
Sprinkle lightly with water, then keep the soil evenly moist during growth.