Fall Care of Newly Planted Trees

Proper Care Now Contributes to Success Next Spring

As autumn settles over Iowa, it’s easy to think gardening season is winding down. But for trees — especially those newly planted — fall is a critical time for care and preparation. According to horticulture specialists with Iowa State University Extension and Outreach, this season offers an opportunity to help trees establish and prepare for the challenges of winter.

Watering

Aaron Steil, consumer horticulture specialist with ISU Extension and Outreach, reminds gardeners to sufficiently water newly planted trees. “This spring started off with plenty of moisture, which provided much of the water a newly planted tree or shrub needs to stay healthy and establish well,” he said. “This fall has been much drier, which means we have to do a better job of regular watering.”

Gardeners should frequently check soil moisture and water when the original root ball or surrounding soil is dry to the touch 1 or 2 inches deep, noted Steil. “For trees planted in the spring, it is necessary to thoroughly water the original root ball and the surrounding soil to encourage new root growth into the surrounding area.” Steil also recommends using soaker hoses and spot sprinklers to make it easier to irrigate this larger root zone and to water until the ground freezes.

Jeff Iles, professor and horticulture extension specialist at Iowa State, also emphasized the importance of good watering for winter survival. “Properly watered young trees are less likely to develop tip dieback and sunscald,” he said. Evergreen trees and shrubs are particularly prone to developing brown, dead tips when they enter winter dormancy with dry root zones. “While the causes of sunscald — the development of elongated, sunken, dried or cracked areas of dead bark — is not well understood, we do know it is more common on young trees with smooth bark that go into winter drought-stressed.”

Wildlife

Fall is also the time to prepare young trees for hungry wildlife. “During the winter months, when food is scarce, rabbits and other rodents will chew and strip bark from woody plants,” Steil explained. To prevent this damage, he recommends wrapping young tree trunks with protective tree wrap in late fall and removing it in early spring. “Make sure protective wraps or fencing is at least 3 feet tall, as animals can get over shorter fencing if there is deep snow,” he added.

Deer also pose a threat, especially to young trees. Their antler rubbing can severely damage trunks, while browsing can stunt growth. Steil advises installing fencing or cages around vulnerable trees and shrubs. “Stakes and fencing must be sturdy and at least 4 feet tall to prevent antler rubbing,” he said.

Planting

“Fall is an excellent time to plant deciduous trees,” noted Iles. “The warm soil and cool air temperatures promote root growth.” Iles emphasizes that while deciduous trees can be planted from mid-August through early November, evergreens like pine and spruce should be in the ground by the end of September to avoid winter injury.

Tasks to avoid

Some garden tasks are best left alone. “It may seem tempting, but do not prune woody plants in the fall,” cautioned Steil. “Pruning encourages new growth, and when done this time of year, that growth won’t be well hardened off for winter, increasing the risk of damage.” Instead, he recommends waiting to prune until late winter or early spring when trees are dormant, typically from February through March in Iowa.

Fertilization, too, should be postponed. Most Iowa soils provide adequate nutrients during the establishment phase, and fertilizing late in the growing season can do more harm than good. “Like pruning, fertilization encourages new growth that will not be well-conditioned to overwinter without seeing damage,” Steil noted.

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Watering

Wildlife

Planting

Tasks to avoid

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