Et cetera : Yard and Garden: Planting Trees in Spring

Backfilling soil around the base of a newly planted tree

Spring tree planting tips for success

Spring is a time of renewal, growth and new beginnings. Planting a new tree (or trees) is a great way to add beauty to your landscape, improve air quality, provide wildlife habitat and reduce home energy consumption. Planting trees requires specific steps and aftercare to ensure a successful outcome. In this article, Iowa State University Extension and Outreach horticulturists answer your questions about how to best plant new trees that will enhance your landscape and create a legacy that will be enjoyed for generations.

What is the proper way to plant a container-grown tree?
Start by locating the trunk flare of the tree. This is the spot on the trunk that broadens just above the major roots of the tree. It is common for trees to be planted too deep in containers. Remove any soil off the top of the root ball to expose the trunk flare if needed.

Dig a hole two to three times wider than the diameter of the container. The depth of the hole should be the height of the root ball (after the extra soil has been removed to reveal the trunk flare). Slope the sides of the hole so the top of the hole is several inches wider than the bottom. In poorly drained soils, the depth of the hole should be approximately two-thirds of 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, then slide the tree out of its container. 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, checking to ensure the trunk flare is at the same level as the surrounding soil.

Gradually fill the hole with the same soil that was dug from the hole. Firm each new addition of soil in place with your hands. When finished, the backfill soil should match the surrounding grade or site soil. Again, when planting in poorly drained soils, the backfill soil should gradually slope down to the surrounding site soil. Once planted, water thoroughly.

Should compost or sphagnum peat moss be added to the soil when planting a tree?
Do not add compost, Sphagnum peat moss, or other organic materials to the backfill soil when planting trees. Research studies have shown no benefit to adding organic amendments to the backfill. In other words, trees will not establish any sooner or grow any faster when organic amendments are added to native site soils and used as backfill.

Can I replant a new tree in the same spot after removing an old tree?
A new planting site is best for any new tree. If any of the old tree's roots are still in the ground, it will be difficult to prepare an adequate hole for the new tree. Also, sawdust left behind from grinding and removing a stump may drastically change the structure, moisture-holding capacity, and nutrient balance of the soil, making it difficult for the new tree to become established and grow.

Most of the issues encountered when attempting to plant in the exact same location as an old tree stump can be avoided by planting at least three feet (ideally six to eight feet) away from the removed tree. If you encounter large roots or other obstructions in the new nearby planting location, simply shift the planting hole to avoid the obstruction.

Do not plant a new tree in the decomposing stump of an old one. While occasionally this will be observed in nature, planting a new tree in the decaying stump will not be successful because of unsuitable soil, limited space for rooting and poor moisture availability.

How do I care for a newly planted tree?
The most important thing you can do to have success with your new tree is to provide consistent and proper care during the establishment period, which for most container-grown trees is one to three years.

Regular and consistent watering is essential for newly planted trees. The roots of newly planted trees are initially confined to the plant's root ball. Check the moisture status of the plant's root ball and the surrounding soil regularly. Water when the soil begins to dry out by slowly applying water to the root ball and surrounding soil. Newly planted trees often need water every day for the first four or five days after planting as the root ball can dry out quickly. Gradually reduce the watering frequency over the next two to three weeks to every 7 to 14 days as roots begin to grow into the surrounding soil. Regularly check soil moisture all summer and into fall, applying water when soil conditions are dry.

To help conserve soil moisture, place 2 to 4 inches of mulch, such as wood chips or shredded bark, around trees. Typically, mulched areas are circular and extend outward from the trunk as wide as the branch spread or canopy. Mulches also help control weeds, moderate soil temperatures and reduce the risk of mechanical damage to tree trunks from errant lawnmowers and string trimmers.

Do not severely prune the branches of newly planted trees. Pruning and the subsequent removal of foliage reduces the tree's ability to manufacture food and slows plant growth. Additionally, it is generally not necessary to fertilize newly planted trees. Most Iowa soils supply sufficient nutrients during establishment.

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, stabilizing materials and techniques should 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.