The first year is the most important period in the establishment of newly planted trees. Good cultural practices help trees overcome transplant stress and create a favorable environment for tree growth.
The most important requirement for newly planted trees is an adequate supply of moisture. During dry weather, trees need to be watered about every 7 to 10 days throughout the first growing season. (Soil type and weather conditions determine the actual watering frequency.) Water trees slowly, but deeply. Continue to water until the ground freezes in winter. Since large trees take longer to become established in the landscape, it is often necessary to water large trees for 2 or 3 years.
To help conserve moisture, place 2 to 4 inches of mulch, such as wood chips or shredded bark, around trees. Mulches also help control weeds, moderate soil temperatures, and reduce the risk of mechanical injury to tree trunks from errant lawnmowers and string-trimmers.
It is generally not necessary to fertilize newly planted trees. Most Iowa soils can supply sufficient amounts of nutrients during establishment. Fertilize trees 2 to 3 years after planting if they are growing poorly or possess light green foliage.
Trees utilize sugars and other carbohydrates manufactured by the foliage for plant growth. Therefore, avoid the temptation to severely prune trees to compensate for root loss during transplant ing. Severe pruning of newly planted trees reduces their ability to manufacture food and actually slows plant growth. Newly planted trees require only corrective pruning. Remove defects, such as double leaders and dead, broken, or crossing branches. Retain most of the lower branches. These lower branches help stabilize the tree and its foliage manu factures food for the growing tree. Gradually remove the lower limbs as the tree grows during the first 10 to 15 years.
Staking of most newly planted trees is unnecessary. However, top-heavy trees and those planted in windy, exposed areas may require staking. If stak ing is necessary, allow the trunk to move or sway for proper trunk and root development. To prevent damage to the trunk, use strong, wide strips of rubber, canvas, or other materials to support the tree. Remove the stakes as soon as possible. Stakes can often be removed after one growing season.
Wrapping protective materials around the trunks of newly planted trees is usually not neces sary. There appears to be little or no benefit to tree wraps. In fact, most scientific research has found that wrapping trees may cause problems. If you do decide to use a tree wrap, place it around the tree in fall (November) and promptly remove it the following spring (April).
Newly planted trees do require special care during establishment. However, the rewards for our efforts are healthy, attractive trees which should provide enjoyment for many years.
This article originally appeared in the May 10, 1996 issue, p. 72.