There are many reasons besides celebrating Arbor Day on April 29 to plant a tree -- trees conserve energy, bring beauty to the yard, attract birds and help clean the air, to name just a few. Iowa State University Extension garden experts have tips for planting trees and caring for newly planted trees. Gardeners with additional questions can contact the experts by calling or emailing the ISU Extension horticulture hotline at 515-294-3108 or firstname.lastname@example.org.
When planting a balled and burlapped tree, dig a hole that is two to three times wider than the diameter of the tree’s rootball. The depth of the hole should be two or three inches less than the height of the rootball. Slope the sides of the hole so the top of the hole is several inches wider than the bottom.
Grasping the tree’s rootball, carefully lower the tree into the hole. The top of the rootball should be approximately two or three inches above the surrounding soil line. Make sure the trunk is straight. Then begin backfilling with the original soil. Do not add compost, peat or other organic materials to the soil. Gently firm the backfill soil in the hole with your hands.
When the planting hole is one-half full, cut and remove all twine. Also, cut away and remove the burlap on the top one-third to one-half of the rootball. If the rootball is in a wire basket, remove the top one-third to one-half of the basket. Completely fill the remainder of the hole with soil. Place soil up to the top of the rootball and gradually slope it down to the surrounding soil line. Thoroughly water the tree.
Poorly drained sites are difficult locations for many trees. When selecting trees for these sites, choose trees that can tolerate poorly drained conditions. In poorly drained soils, the depth of the planting hole should be approximately two-thirds of the height of the rootball. When placed in the hole, the top one-third of the rootball should be above the surrounding soil. Fill the hole with soil. Place soil to the top of the rootball and gradually slope it down to the surrounding soil line.
When planting a container-grown tree, dig a hole that is two to three times wider than the diameter of the container. The depth of the hole should be two or three inches less than the height of the soil ball. Slope the sides of the hole so the top is several inches wider than the bottom. In poorly drained soils, the depth of the hole should be approximately two-thirds the height of the soil ball.
Once the hole has been prepared, carefully lay the tree on its side. Tap the sides of the container to loosen the soil ball from the container, and then slide the tree out of its container. All containers should be removed, even supposedly plantable containers. If the sides of the soil ball are a mass of roots, carefully shave off the outer ½ to 1 inch of the soil ball with a sharp spade or saw. Place the tree in the hole. The top of the soil ball should be approximately 2 or 3 inches above the surrounding soil. In poorly drained sites, the top one-third of the soil ball should stick above the surrounding soil.
Gradually fill the hole with soil. With each new addition of soil, firm it in place with your hands. Place soil to the top of the soil ball and gradually slope it down to the surrounding soil. Once planted, water thoroughly.
It is generally not necessary to fertilize newly planted trees. Most Iowa soils can supply sufficient amounts of nutrients during establishment. If trees are growing poorly two or three years after planting, fertilization may be beneficial. Poorly growing trees often exhibit sparse foliage, yellow-green leaves or short annual twig growth.
Staking is not required for most newly planted trees. However, large trees and those planted in windy, exposed sites may require staking. If staking 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 canvas, rubber or other materials to support the tree. Remove the stakes as soon as possible. In most cases, stakes should be removed after one growing season.
Trees utilize sugars and other carbohydrates manufactured by the foliage for plant growth. Therefore, avoid the temptation to severely prune newly planted trees. Severe pruning reduces the tree’s ability to manufacture food and actually slows plant growth. Newly planted trees require only corrective pruning. Remove structural defects, such as double leaders and dead, broken or crossing branches. Retain most of the lower branches to help stabilize the tree. The lower branches also provide food for the growing tree. Gradually remove the lower limbs as the tree grows during the next five to 10 years.
The key to watering newly planted balled and burlapped and container-grown trees is to keep the plant’s rootball moist for several weeks after planting. Water newly planted trees every day for four or five days and then gradually reduce the frequency of watering. When watering, slowly apply water to the rootball and the surrounding soil. A thorough watering every seven to 14 days (in dry weather) should be sufficient four to five weeks after planting. Continue this watering schedule through summer and into fall. Small trees usually require watering for one or two growing seasons. It may be necessary to periodically water large trees for two or three years.