1. Prepare a planting hole
Dig a hole three times the width of the root ball and slightly shallower (1 to 2 inches) than the root ball. The root ball is comprised of all the roots contained in a container or burlap. The top of the root ball begins where the roots start to emerge from the trunk. If your planting hole has slick sides, loosen the sides and bottom with a pick or shovel. This makes it easier for root tips to penetrate into the native soil.
2. Add soil amendments
If your native soil is hard to work with (e.g., heavy clay) or retains little moisture (e.g., very sandy), you can treat it to some organic amendment, such as compost. The amendment won’t be a permanent solution to soil deficiencies, but it will help retain water and air in the soil around the root ball for the first few vital years. If adding soil amendment, always mix it with soil from the planting site; about one part amendment to three parts native soil is a good proportion for backfill soil.
3. Place tree in planting hole
Remove the container from the tree. Sometimes when a tree is grown in a container, the roots tend to grow circular in the container. Check the root ball for circling roots. If circling roots are left in place near the trunk, they will cut into the trunk as the trunk's girth expands. Gently uncurl and straighten the roots so that they are going outward from the trunk. If a circling root is too stiff to move, you may need to cut the roots, but be careful not to cut off too much of the root ball. Gently lower the tree into the hole. If the tree has not been containerized and instead the root ball is wrapped in burlap, do not remove the burlap. Place the tree or shrub in the planting hole with the burlap intact. Untie any string that is tied around the base of the trunk.
4. Don’t bury the trunk
If soil covers the base of the trunk, the trunk will rot. Aim to have the top of the root ball about 1 to 2 inches above the surrounding soil surface. Adjust the depth of the hole by lifting the tree out of the hole (lift it by the root ball, not by the trunk) and adjusting the soil level in the planting hole.
5. Orient the tree
Orient the tree while you have the chance. Situate it so that branches won’t be in the way of pedestrian or car traffic. If you prefer a particular side of the tree, turn it toward a prominent viewpoint. When turning the tree, lift it from the base of the root ball, not from the base of the trunk. Once the tree is in the hole, stand back and make sure it’s standing upright. Tilt the root ball until the tree is straight, then backfill firmly under and around the root ball.
6. Pack the soil
Pack down the soil as you backfill. Using the heel of your foot or the handle end of the shovel, press down firmly to collapse any large air pockets in the soil. This will help stabilize the tree in the hole. Don’t wait until the planting is finished; press down every few shovels of soil.
Build a watering basin around the root ball by creating a berm a little larger than the root ball perimeter. This concentrates water to the root ball. A tree that has a dry root ball can stand in a moist backfill without absorbing water. You'll need to water your tree thoroughly after planting. Monitor your tree's water needs everyday for the first month. This will give you an idea as to the frequency your tree will need water.
Stake the tree loosely for protection or support if needed. Use only soft, pliable tree ties. If the trunk can’t stand up on its own, stake it so that it stands upright. The stakes should be placed outside of the root ball. Plan to remove stakes as soon as the tree can support itself, in 6 to 12 months.
Cover the entire planting area with a layer of mulch, but keep it 2 inches from the base of the trunk. Mulch keeps the topsoil temperate for root growth, reduces surface evaporation of water, slows or stops weeds and grass growth around the tree’s base.