WESTCHESTER COUNTY, N.Y. -- Some of our most important native plants are “woodies” (trees and shrubs). Woodies provide critical structure and ecological function to our landscapes – some are early pollen sources for hungry bees, some are nesting sites for songbirds, and some, primarily evergreens, provide cover to many creatures during harsh winters.
Fall is a great time to plant many trees and shrubs. Some woodies, including broadleaved evergreens like Rhododendrons and Mountain Laurels, are better planted in the spring, as are some spring bloomers like Magnolias. But, for many deciduous trees and shrubs, fall planting is ideal. The warm days and cool nights of fall promote healthy root growth.
Plan to get any new plants in the ground by the end of September. Ideally, new plants should have at least 6 to 8 weeks to establish before hard frost. Guessing the date for hard frost has become more challenging in the face of unpredictable weather events that accompany climate change. In recent years the tri-state region has experienced two heavy snowfalls in late October. If you plant by mid-September, you should be safe.
Here are some tips for planting trees and shrubs in fall:
Skip the fertilizer, unless you have gotten a soil test that indicates a deficiency of some sort. Large fertilizer companies have trained us to apply fertilizers whether plants need them or not. Most times, plants don’t need them. If you have a known soil deficiency, slow-release, organic fertilizers are the way to go. Use half of the rate recommended by the manufacturer. Less is more, and usually that’s plenty.
Many plants that you purchase from a nursery, a garden center, or a big box store, have been excessively fertilized to push lots of growth. After all, bigger plants sell better. The problem is that many fertilizers contain large quantities of salts that are very desiccating to plants. These salts can cause significant damage to a plant’s root system as the salts absorb water that would otherwise go to the plant’s roots.
When planting new trees or shrubs in the fall, it is particularly important to water the roots of your new plants until hard frost occurs. Fall watering will lessen the negative impact of fertilizer salts used by the grower. It will also help plants establish a healthy root system before winter sets in. This adds up to a better survival rate through winter.
There is a bit of a science to watering. Deep, less frequent watering promotes deeper roots and makes for a more drought tolerant plant. Two deep waterings a week by you or Mother Nature should suffice. When you water, do it early in the day, focusing on the roots. Skip overhead watering, which is notorious for creating fungal problems, and is also highly inefficient and wasteful.
Increase the health of your woody plants by building healthy soil. Compost and compost teas can be invaluable in improving soil health. Always use the best quality finished compost you can make or buy. Finished compost should have no foul odor and should be quite well decomposed, devoid of large chunks. Add compost and/or a drench of compost tea to the root zone of all of your woody plants in the fall, for a late season health boost.
Take care of those valuable native trees and shrubs this fall. You’ll be glad you did, when spring comes around!
Kim Eierman, a resident of Bronxville, is an environmental horticulturist and Founder of EcoBeneficial! When she is not speaking, writing, or consulting about ecological landscapes, she teaches at the New York Botanical Garden, Brooklyn Botanic Garden, The Native Plant Center and Rutgers Home Gardeners School.