Champaign, Ill. (WCIA)
Ryan Pankau, Illinois Extension Horticulture Educator, shares fall tree planting tips.
Fall Tree Planting
Most folks think of spring as the ideal planting time for trees and shrubs. However, fall offers a nice planting window with some added benefits over the spring season, making it my favorite time of year to establish woody plants.
Fall weather can create ideal planting conditions, with temperatures cooling off and roots requiring less moisture. In addition, we typically get a good amount of fall rains to help ensure adequate soil moisture going into winter.
Although woody plants will experience dormancy in winter, root growth can still occur when soil temperatures are warm enough. This little bit of growth over winter, along with the fact that the soil has settled nicely, sets the tree up to hit the ground running when spring occurs.
When we plant in spring, soil moisture is typically high and plentiful rainfall can be expected, but shortly thereafter summer hits. Summer is time of high temperature and relatively low soil moisture. It’s a time where stresses on trees from drought, pest pressure or plant disease are serious, making the spring season less ideal for planting.
Transplant shock is something that all newly planted trees and shrubs experience, which typically lasts for 2-3 years following transplant, or even longer.
To overcome transplant shock trees and shrubs need to expand their root system beyond the planting hole. A mature tree will typically have a root system 2-3 times wider than the spread of its limbs. When you think about that ratio and how it would measure on a newly planted tree, it takes considerable time for a transplant to develop adequate roots and overcome transplant shock.
We can really help a tree overcome transplant stress by digging a shallow and very wide planting hole. The wide hole of well-loosened soil provides a nice medium for expanding root growth.
Your planting hole doesn’t need to be deep for a few reasons. First off, the majority of tree roots are concentrated in the upper 12-18 inches of soil. So there is no need to dig a hole much deeper. Secondly, and most importantly, it is critical that your tree is planted at the proper depth, which is typically much more shallow than expected.
To determine the proper planting depth, start by identifying the root flare, or trunk flare, on your new tree. This is the portion of the trunk at the bottom of a tree that begins to flare out, or taper out, as trunk tissue transitions into root tissue. Your tree needs to be planted so the trunk flare is at the soil surface.
Trees that are planted too deep really struggle to get established and often suffer from a lifetime of other issues. It is the most common mistake in tree planting because we often plant our new trees at the depth of the container or root ball. However, the root flare of the tree is typically buried in the pot or the root ball on most nursery stock.
Before digging the planting hole, start by identifying the root flare on your new tree. In some cases it will be easily visible at the surface of the pot or burlap in a ‘balled and burlapped’ plant. If it isn’t easily identifiable and the trunk has little flare where it enters the pot or burlap, gently dig down along the trunk into the container or root ball to search for the first roots coming out of the trunk. Take care when digging around the trunk as young trees have thinner bark, which is more susceptible to damage. Carefully excavate soil to expose the trunk flare, or sometimes the trunk will have little taper on a young tree, making the first root or roots your best indicator of the root flare depth.
Once you have identified the root flare, dig an appropriately deep hole that is significantly wider than it is deep. Gently place your plant, with the pot or burlap removed, into the hole and take a step back to be sure it is fairly straight before backfilling. Use the soil from your planting hole to carefully backfill around the tree’s root ball. Add a 2-4” layer of mulch over all the loosed soil in your planting hole and your tree is all set.
You may need to water your tree periodically this fall until cold weather sets in. Plan to water your tree thoroughly once a week for each week we don’t receive one inch of rainfall until about Thanksgiving. Your tree should be nicely tucked in for the winter by late November and will be ready to grow when spring rains begin next year. Next summer and the following summer your tree will need water each week we don’t receive an inch of natural rainfall to ensure it gets well established in its new home.