The BEST Way to Plant a Tree
How would you like to give your newly-purchased potted tree (or shrub) a better chance at a long and healthy life? Taking just a just a few extra minutes when you plant to follow these steps can have a huge impact in the following weeks, months and years, and helps to insure your investment.
Let’s start with the assumption that you have prepared the ideal planting hole: twice as wide as the root ball, and not quite as deep. You’ll want the top of the root ball to sit an inch or two above grade.
For container trees, gently remove the pot. For really large containers, it’s sometimes easier to cut from the rim to the bottom in several places and bend the sides down flat. Heavy shears or a sharp utility knife will work.
Here’s where the critical part comes in: preparing the root ball. Observe the sides of the root ball. If there are lots of roots visible you will want to loosen them well. To do this you can use your fingers, or a small garden fork or claw. If you don't have a claw, you can also make several cuts across the rootball with a knife or pruning saw. The new roots that form at the cuts will root outward.
(click on any picture to enlarge)
Don’t be afraid to be firm, you want to straighten or remove the roots that are growing in a curve around the root ball. If not addressed, they will continue their circular path when what you want to encourage is growth outward from the root ball.
Tip the root ball over to look at the bottom. If you see a “pancake” of roots, these must be loosened also. Tease or cut tease them apart like you did the sides. It’s also OK to prune stubborn roots off if necessary to open up the tangles. In extreme cases the entire disc of roots can be sawed off. If no “pancake” has formed, loosen any roots you do see the same as on the sides.
It’s possible—even likely— that while loosening roots that a small percentage will be lost. This is not bad for the tree. Like pruning the stems and branches, pruning the roots* encourages new growth that will help the tree to get established more quickly.
Finally, check that the trunk flare is visible above the soil level. There should be a slight widening of the trunk above soil level, possibly with a change of texture. If it’s not visible, gently remove soil from the top of the root ball until you can see it. You may end up removing some roots along with soil if you need to do this, which is a good thing. These roots can become circling roots that can end up strangling the tree in the future.
Preparation for ball-and-burlap trees is somewhat different. Because B&B are not grown in plastic containers, circling roots are not usually present but the twine or strapping and burlap can cause similar problems if not prepared properly.
Gently place the root ball in the prepared hole. Avoid dropping the root ball which can cause the ball to break, possibly shearing off more many roots than the tree can handle losing.
Back fill the planting hole with amended soil. In most cases, adding soil conditioner (finely ground pine bark) at a ratio of one part to 4 parts soil is a good proportion. Adding BioTone Starter can help roots establish. Do not add non-organic fertilizers to the backfill soil as they can damage the roots.
One method to both settle the backfill and provide adequate moisture at the root zone is to gently water in the backfill as you go: add a layer of soil, water to settle, add more soil, water etc. If you choose to not water as you backfill, add soil gradually making sure there are no air pockets. Leave the top of the root ball uncovered by soil, and at or slightly above soil level.
Build a wall of soil approximately 3-4” high in a ring at the edge of the planting hole. This will help direct irrigation water to soak into the root zone instead of running off.
Finally, add a layer of mulch from a few inches away from the trunk to the drip line (the width of the widest branches) and about 2-3” deep. Water the tree slowly but deeply (see below), being sure to moisten the mulch also. Wet the mulch every time you water—while mulch keeps the moist soil from losing water due to evaporation and inhibits weeds, it can also resist irrigation and rain if it gets too dry or too deep.
The preparation of the roots will take a little extra effort, but it will encourage the growth of fine roots that supply water and nutrients to the tree. It also prevents the roots from continuing the circular growth that the pot encourages. Roots that circle the trunk can end up causing the tree to decline many years down the road, often so severely that the tree dies or must be removed for safety reasons. This decline can be so slow and so long after planting that you may not realize that that was the cause of death for a seemingly healthy tree.
Watering Newly Planted Trees
Water by turning your hose on to a slow trickle that soaks into the soil without running off. (If you built a soil ring when you planted you can run the water a bit faster.) Let this run for 10-15 minutes. If soil is very dry you may need to do this a few minutes at a time until soil is moistened enough to accept water.
*Some studies (1, 2) have shown that shaving 1” of soil/roots from both the sides and bottom of the root ball can be quite effective in promoting root development, but the number of species tested has been limited. It has also been noted that insufficient irrigation after planting can cause shaved trees to fail. This technique shows promise but needs more research before it can be recommended.