Early Fall Gardening Tips from Linn County Master Gardener
By Lisa Slattery, Linn County Master Gardener
You may think that the joy of gardening is winding down in September but that’s just not so. Late summer into early fall is a great time to be outside enjoying the garden with a cool drink and taking stock of what went right and what went wrong this season. Right now is an ideal time to make changes, move plantings and plant new perennials, shrubs and trees.
Planting woody stock like evergreens, deciduous shrubs and trees now gives them a head start into fall and winter with plenty of time to establish a good root system before frost and cold weather sets in. Most garden centers have plants on sale at this time and have a nice selection to choose from. Trees, shrubs and evergreens can be purchased as either balled and burlapped (which are typically your larger plant stock) or in containers.
From mid August to mid October we generally have moderate and stable temperatures with soil temperatures and moisture levels in a range that promote root development. Trees and shrubs at garden centers generally have well-developed root systems so it’s a win-win situation. Evergreens prefer a slightly earlier start, so plant those from mid August through September.
Late summer and fall planted trees and shrubs should be watered on a regular basis during the remainder of the year. For new trees and shrubs water daily for the first two weeks, and every two to three days for the next three to twelve weeks. Ask your garden professional about proper water requirements for your new plant, as requirements differ. Continue watering until the ground freezes in winter.
Early fall is also a great time to plant new perennials with warm days, plenty of sunshine and cooler night temperatures. It’s also a good time to divide some perennials. Rule of thumb dictates that spring and early summer blooming perennials should be divided and transplanted in the fall – so now is the right time to divide and transplant peony, daylily, and oriental poppy.
Keep perennial transplants properly watered. An inch of water a week is a good general rule, preferably watering in the mornings so as not to invite unwanted pests and diseases by having damp foliage at night. Don’t fertilize anymore. Late season fertilization encourages late season growth that is easily damaged in winter. But do continue to deadhead and weed your flower beds.
Newly planted or transplanted perennials should be mulched with 4 to 6 inches of straw, pine needles or other organic materials in late fall. Mulching helps prevent plants from heaving out of the ground if we have repeated freezing and thawing of the soil.
Many herb and vegetable gardens are at their peak in August. This is apparent in the wide variety of locally grown fruits and vegetables available at the various community-wide farmers markets. In your own garden, plan to harvest potatoes and onions when the tops die back. Harvest tomatoes when they are fully colored. If you leave them on the vine an extra day or two it’ll enhance their flavor. Continue to harvest beans, squash and cucumbers to keep the plants productive. Lettuce, spinach and radish seeds can also be planted in early September for a harvest later this fall.
Lawns are usually looking pretty good in September unless we’ve had a dry summer, like we have this year. But mid-August to mid-September is the best time to seed new lawns and over-seed existing lawns. Late summer planting has advantages over spring seeding. The seeds of cool-season grasses germinate quickly in the warm soil of late summer.The warm days and cool nights of early fall promote rapid turfgrass growth. The growing grass also has less competition from weeds as few weed seeds germinate in the fall.
If you do seed, keep the upper 1 inch of soil moist with frequent, light applications of water. Most turfgrasses should germinate in two to three weeks if the seedbed is kept uniformly moist. Gradually reduce the frequency of watering, but water more deeply, when the turfgrass reaches a height of 1 to 2 inches. Mow the grass when it reaches the height of 3 to 3 ½ inches.
Continue to remove weeds and keep plants mulched. Play catch-up in your garden journal noting what you liked best this summer and what you might like to change or add for next summer. Take photographs of plants you like as well as things you’d like to change. But most important, don’t forget to sit down and admire your garden.