Don't you experience a "new world" feeling in September? Afternoon light changes (what a poet described as "tea colored light"), trees blend into autumn color and the garden beckons...

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Don’t you experience a “new world” feeling in September? Afternoon light changes (what a poet described as “tea colored light”), trees blend into autumn color and the garden beckons us back after the dryness of August.

Gardeners prosper from responding to the tempos of the season, and September and October are among the most delightful of gardening months. Though we’re troubled by dwindling light, as the evenings slip toward winter’s tunnel of dark, still the soil is warm, protecting our knees from the icy chills of spring, the sun touches our necks and our gardening rhythm can resume.

Here’s how to fall back into it:

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Review the garden now. You may notice trees and shrubs poking a few blooms out of season (forsythia, some rhododendron). Until fall rains really set in, plants continue to respond to heat and drought, and one of these stress responses is odd blooming patterns.

You’ll also see trees dropping leaves or turning color earlier than usual. Early leaf drop is a protective, adaptive mechanism and not necessarily a cause for worry. (This is generally true for large, established plants.) If you suspect a plant has succumbed to drought, you may want to wait to remove it until spring; sometimes plants will recover and send up new shoots despite the death of their tops. Five out of seven of my evergreen huckleberries (Vaccinium ovatum) look dead, but I’m hoping for a spring resurrection of their root growth.

If you planted trees or shrubs this year, do keep watering. Plants require water in direct proportion to the state of their roots: The less developed the root system, the more it needs irrigation now.

Lawn care is a primary task for fall. Some of you may be chortling over this, considering that many lawns resemble doormats after a summer that brought us about an inch of rain. Most turf will recover, growing back from the roots when rain returns. Dig or spot-treat weeds (you’ll be able to find the weeds, since they’re still green). If the lawn needs thatching or aerating, do this now.

Thatching yanks dead stems and roots from grass crowns. Aeration pokes holes and pulls out wads of turf (and is easier to do after a couple of rainstorms have dampened the ground.) Both processes improve next year’s water penetration into turf. After these efforts, you’ll see scalped spots in the lawn. Fill those in with new seed.

Fall’s a good time to overseed, filling in open spots with a Northwest seed mixture. Grass can be planted from seed up to about Oct. 15, but later than that it usually doesn’t grow fast enough to fill in before winter. (Sod can be laid almost any time.) Don’t allow baby grass blades or new sod to go dry.

Divide spring-blooming perennials. September and October are good months for dividing plants and for sharing them with neighbors and friends. (If everyone brought plant divisions to fall youth soccer games, think of the garden expansion this might cause!) Iris, peonies, Shasta daisies, Oriental poppies all divide well now. Amend the new planting area with compost, and don’t allow roots to desiccate before replanting.

Bare ground? If you’ve cleared an area for future landscaping, give it a winter cover crop. Plant crimson clover or other cover crops now to be tilled in during spring. Without winter cover, soil becomes compacted from rain and covered with winter weeds. Or you can gather fallen leaves and pile them 4-6 inches deep on any bare spots. In any case, don’t allow soil to head for winter without a cozy covering.

The four primary gardening months in the maritime Northwest? March, April, September and October — sharpen your tools to greet fall’s tasks with gusto.

Mary Robson is area horticulture agent for Washington State University/King County Cooperative Extension. She shares gardening tips every Wednesday. Her e-mail is