By Olivia Lenahan
Horticulturist
Iowa State University
As the trees shake off the last of their fall display, it may be tempting to put away the yard tools and close the garden shed for the season. After all, your plants have finished growing this year. But now is the time to ready your woody plants for the upcoming winter. A few preparations in late fall will go a long way to promote healthy vigorous growth in the spring.
By now, many trees and shrubs have started to harden-off – that is, developed cold tolerance in response to the shorter days and cooler temperatures of early fall. While shoot growth has stopped for the year, roots continue to grow until the soil freezes in winter. Most well-established trees and shrubs in the landscape do not need to be watered in fall. However, there are exceptions. Trees and shrubs planted in the last two or three years are still establishing their root systems and often benefit from fall watering.
Evergreens, such as rhododendrons and boxwoods, are susceptible to desiccation injury, which shows as browning of leaf margins in spring, and would also benefit from watering if the area is experiencing a dry fall. Watering may also be helpful to narrow-leaved evergreens, such as yews and arborvitae. Continue to monitor soil moisture and quench your woody plants’ thirst until the soil freezes and the roots are no longer able to uptake water. Be sure to avoid over watering to prevent root rot.
It is generally not necessary to fertilize woody plants in the home landscape. Most soils in Iowa contain adequate levels of nutrients for trees and shrubs. However, poorly growing trees and shrubs may benefit from an application of fertilizer. Woody species deficient in nutrients may exhibit sparse foliage, yellow-green foliage, or short annual twig growth. When beneficial, fall is an excellent time to fertilize trees and shrubs. Apply a balanced fertilizer, such as 10-10-10, to trees and shrubs that are at least one-year-old. Be sure to broadcast the material uniformly over the root zone and with sufficient water so that roots can absorb nutrients. Providing your woody plants essential mineral elements just before winter will enhance next season’s growth.
Woody plants can quickly become a buffet line for rabbits and deer in winter, especially when the ground is covered with snow and food is scarce. Fortunately, you have a number of options that should reduce animal browsing in your garden. Repellents, available in your local garden center, are composed of various ingredients and can repel animals by smell. Apply the repellent directly to the plant while the temperature remains above 40 degrees F, and, depending on the animal traffic in your yard, repellents must be reapplied frequently for best protection. Unfortunately, repellents are not always effective especially in areas with high animal populations.
Trunk wraps are another way to protect the base of your shrub or tree from gnawing rodents and rabbits. However, fencing is the most reliable way to prevent rabbits and deer from damaging trees and shrubs in the landscape. A chicken fence, at least 24 inches high, will keep rabbits away from your woody plants. To thwart deer, make the fence a few feet higher than the top of your shrubs and young trees. Anticipate that the snow fall will make it easier for animals to reach your woody plants and plan your fence heights accordingly.
Take advantage of these lingering golden days of fall to prepare your woody plants for the arrival of Old Man Winter. Your plants will appreciate the protection from winter’s challenges and reward your efforts in spring with healthy growth and spring blooms.
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