Jennifer Schultz Nelson
Extension Educator, Horticulture
Though the growing season is winding down, there is still time to plant trees. In fact, planting trees in fall is probably a little better than planting them in the spring, and certainly a lot better than planting in the heat of summer.
The big advantage to fall planting of trees is that the soil is already warm. This warmth will promote root growth and recovery from any stress associated with planting. Root growth will continue well into the fall, until the soil freezes, giving the tree a head start on next spring.
When we buy a tree to plant, most of us don't give a second thought about what our tree has been through before it gets to our yard. A tree that is balled and burlapped has lost about 90 to 95% of its roots during the process of being dug up and prepped for transplanting. After being planted in a new location, it is not uncommon for these trees to experience transplant shock, a period of low vigor and slow growth. They need time to re-grow roots to support the rest of the tree before their growth can return to normal.
There is some truth to the notion that a tree grown in a container will not have this drastic reduction in roots before planting, so it should not have as much transplant shock. But if a container grown tree has a lot of crowded, circling roots in the container that need to be cut before planting, you will still see transplant shock.
Balled and burlapped trees are usually much bigger than container grown trees, making them very attractive to new homeowners that lack any trees in their landscape. But with bigger size comes a bigger price. Container grown trees tend to be more affordable.
If you can cultivate a little patience along with your tree, a container grown tree will match the size of a balled and burlapped tree in a relatively short time. I have seen first hand where the homeowner had a mixture of the same trees, some balled and burlapped, some container grown, and within 5-7 years the container grown trees were the same size as the balled and burlapped trees.
The difference in growth is related to transplant shock. The balled and burlapped trees spend much more of their energy on re-growing roots in those first 5-7 years, while the container grown trees don't have as much loss of roots prior to planting, so they establish quicker and can channel more energy towards growth of leaves and branches.
Site selection and preparation is critical to the survival of any tree, whether balled and burlapped or container grown. A saying I've heard is "if you have a $20 tree, dig a $200 hole". Give your tree the best possible start, and it will beautify your home for many years to come.
Pay attention to the full grown size of the tree you want to plant. I get a lot of questions from homeowners related to trees that have grown way too big for where they are. My "classic" example of this is the Colorado Blue Spruce. These trees are very attractive, cute little perfect trees when they're purchased at the local nursery.
Many people plant them right on the corner of their house or along their driveway, and they look good for a while. This tree may reach 30 to 60 feet when mature. Usually that's when people call me, wondering what to do with this tree that has totally outgrown its space. It's a rare person that calls and asks before they plant the tree to begin with. A little research before you plant will save you a lot of grief years down the road!
When actually planting your tree, it may surprise you that the hole doesn't need to be all that deep-- only the depth of the root ball. The hole you dig should resemble a wide shallow bowl rather than a deep pit. It should be three times the diameter of the root ball. Loosening the soil at this diameter makes it easier for new roots to grow into the surrounding soil.
Many of us grew up thinking tree roots grew down very deep. Research has shown that the majority of a tree's roots are in the top 12 to 18 inches of soil, and they may extend several times the width of the tree's canopy.
The rule of thumb for planting trees used to be plant the tree at the same level that the soil is in the burlap or container. This is no longer true, particularly in the case of balled and burlapped trees. As these trees are dug from the field, soil gets pushed up around the trunk of the tree. If you were to plant the tree at this depth, it would be too deep, and the tree would eventually die.
Look for the trunk flare when planting any tree. This is the point at which the roots spread at the base of the tree. I tell people to think of how they drew trees when they were children-- that little curve outward at the bottom does really exist. It is not unusual to have to remove a couple of inches or more of soil from the bottom of a tree to find the flare before planting. Plant the tree so the trunk flare is at the soil's surface or slightly above (2 to 3 inches) to allow for settling.
When you set your new tree in the planting hole, remove any wire, string, burlap, plastic or other debris surrounding the root ball. Anything wrapped around the tree has the potential of eventually strangling and killing the tree.
Look at the tree from several angles to make sure it is straight in the hole before backfilling. Backfill the hole with the original soil a few inches at a time, watering periodically to help settle the soil and avoid air pockets. Apply mulch two to four inches deep, but don't cover the trunk of the tree. Create a raised edge which will help direct water to the root ball. What you end up with should look like a donut (higher at the sides), not a volcano (higher in the middle).
Staking the tree may be necessary if you live in a windy area. Use wide material which will not cut into the bark to hold the tree upright tied to two or three stakes positioned around the tree. Although studies have shown that trees develop a stronger trunk and root system if they are not staked at planting time, this may not be practical. I learned this the hard way at my house.
Most of my trees did fine without staking. One of them is in the wind tunnel that is between our house and the neighbor's. After having to straighten out the tree a couple of times, and then having to replant it because it was uprooted, I decided stakes were a good idea. After all, you can't grow a strong root system when the roots are sticking up out of the ground!
After your tree is planted, follow-up care is still needed, particularly watering. Water when the soil beneath the mulch is dry. Taper off watering in mid-fall, but be prepared to resume watering in the spring. Keep in mind that for at least the first two to three years after planting, your tree will be vulnerable in hot dry weather and should receive extra water.