September garden and gardening checklist  (© Juice Images/Corbis)

© Juice Images/Corbis

As the dog days of summer wane, gardeners welcome the cooler temperatures and perfect planting season. Perennials, trees and shrubs are best planted now: They can spend the winter establishing strong, healthy roots before diverting their energy to spring leafing and flowering. There’s plenty you can do. (Bing: Organic gardening tips)

Dig up, dig in and divide. Roll up your sleeves and think bright thoughts as you plant bulbs for spring flowering. Be sure to give any newcomers a good share of water. Starting now and over the next couple of months, once soil has cooled to less than 60 degrees, plant the bulbs of spring bloomers such as crocuses, anemones, daffodils, hyacinths and tulips in well-drained soil, about three times deeper than the diameter of the bulbs.

  • For an abundant tulip display, place 10 to 20 bulbs in a hole one foot in diameter; plant so that the bulbs aren’t touching.
  • Irises and other early-blooming perennials still can be divided this month. Give them plenty of water after replanting.
  • Dig up and divide or transplant crowded perennials.
  • For swatches of fall color, plant mums, winter pansies, and flowering kale and cabbage.
  • Take cuttings from geraniums, 2 to 4 inches, for indoor winter flowering.
  • Plant perennials from seed by scattering them in an open bed or in individual rows. In the spring, the seedlings can be moved to more permanent locations.

Slide show: 
Plant a garden full of fall color

Trees and shrubs
Fall is an ideal time to shop for and plant new trees and shrubs. They’ll have a chance to establish roots over the winter, and at nurseries you’ll see the beginnings of true fall colors.

  • In many areas, this is the best month for planting evergreen trees and heathers.
  • Choose trees and shrubs with edible berries to provide meals for wildlife, or select for bright splashes of fall foliage.
  • Reduce watering for established shrubs and trees so they can harden off in preparation for winter.
  • Watch fruit trees for signs of mildew.
  • Take cuttings from roses.

How to keep your trees in shape

Lawn care
With just a little bit of effort, you can overhaul your lawn’s health this month to help it thrive in the fall, winter and spring.

  • If September is rainy, begin raking leaves as they fall and grass clippings as you mow; otherwise they’ll form mucky hide-outs for pests.
  • Sod or seed new lawn areas.
  • Overseed bare patches in an established lawn. Your grass will be more lush, and moss and weeds won’t have as much room to take over.
  • If your lawn doesn’t need thatching, over the next couple of months you can apply a fall or winter fertilizer to encourage nice green grass and healthy root development.
  • If needed, thatch now, followed by fertilizing and overseeding.

Pest control
Our old slug friends are starting to lay new eggs right about now. Nip ’em in the bud.

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Check the edges of your lawn and underneath sticks and stones for signs of eggs. They come in nearly translucent clusters of 50 or so, with each egg about the size of a dried pea.

After completing these simple garden tasks, you’ll still have time to enjoy your weekend.

  • Catch weeds now, before they flower. If their seeds have a chance to spread, it means more time on your hands and knees in the future.
  • Remove spent annuals and put their husks in the compost, or use them as mulch for overwintering plants.

Overripening is a September hazard, so check fruits and vegetables regularly. Be sure to harvest them if they look, feel and/or taste ripe and ready.

  • Pick tomatoes if the weather is cooling down, and let them finish ripening indoors.
  • You can now harvest carrots, corn and potatoes. The root vegetables can be harvested for months to come, but corn isn’t as forgiving of cold.
  • Raid those fruit trees: Pick pears, plums and apples now.

Bring houseplants home for the holidays — indoors, that is — and start preparing holiday plants for best health and bright color in December.

  • If you’ve been keeping houseplants outdoors, bring them inside before cool fall nights do any damage. Geraniums and other tender plants also may be moved indoors now.
  • Be sure to place houseplants away from open drafts as the weather cools. And do tender plants a favor: Don’t expose them to direct sunlight — especially through frosted glass, which serves as a magnifier.
  • Starting about midmonth, the time is ripe for “seasoning” poinsettias and Thanksgiving and Christmas cactuses. Give them a daily dose of 10 hours of bright daylight or four hours of direct sun, plus 14 hours of night darkness. Cactuses need a cool environment of 50 to 60 degrees, while poinsettias prefer a warmer 65 to 72 degrees.