Peabody Preserve

Peabody Preserve

Butterfly on coneflower

Butterfly on coneflower

Timely Tips

By Kim Kleman
Master Gardener Volunteer with Cornell Cooperative Extension of Westchester County

Sept. 20

Perennials: Continue to divide and transplant any perennials (peonies, lilies, etc.) that need it. When replanting, unless the plants prefer a “lean” soil, you may add up to ⅓ compost by volume to the hole, mixed well. A layer of mulch approximately one inch thick between plants can help to suppress weeds. Keep mulch from collecting against the base of the plants.

Flowers: Tidy up the flower gardens by removing and composting disease-free dying annuals and fallen leaves. Continue as needed through frost.

Fruits and Vegetables: For a spring spinach harvest, sow seeds of hardy varieties such as ‘Melody,’ ‘Tyee,’ and ‘Winter Bloomsdale’ under a row cover now and surround them with a thick layer of mulch applied when the ground begins to freeze. You may also start them in a cold frame, insulated by mulch around our first hard freeze. They’ll overwinter under the mulch layer for an early spring crop. Keep up with the fruit harvest. Remove overripe, damaged or diseased fallen fruit. These may contain pests.

Trees and Shrubs: Fall is the best time to plant deciduous spring-flowering trees shrubs such as beautyberry, redbud, serviceberry, summersweet, and more. You may also plant needled evergreens, such as cedars, pines, spruces and yewsthrough the end of the month. Wait until spring to plant broadleaved evergreens, Japanese maples and marginally hardy trees and shrubs. Water any new plantings as needed until there is a light freeze.

Lawns:Wait to cut your newly seeded lawn until the grass is about 4 to 4½ inches in height. Remove no more than one-third of the grass blades so at least 3 to 3½ inches will remain after mowing. Water newly established turf as needed up until a light freeze.

Houseplants: If your plants are like mine, they’ve practically doubled their size during their outdoors vacay this summer. They’re not going to fit on the ledge where I had them. Make accommodations for a new place inside with good sun and airflow.

General: To increase the organic matter in the garden soil, add weed-free aged manure, compost or leaf mold this month or next.

The invasive Spotted Lanternfly (SLF) has been detected in areas of the Hudson Valley.SLF is a serious threat to New York agriculture, causing harm to crops like grape vines. If you plan to travel or have recently returned from a state where SLF is established, be sure to check your vehicle and any items kept outdoors for hitchhiking lanternflies (a flashlight and mirror may be helpful in hard to see spaces). See a map of known SLF populations and learn more about this invasive pest and what you can do to help stop its spread at If you find any lanternflies after you return to New York, snap and send a photo to Capture the insect(s) and save it to submit for verification.


Amy Albam
Horticulture Educator/Master Gardener Program Coordinator

Last updated September 21, 2021