There are 2 methods of planting trees, the organic way and the synthetic chemical way. Landscaping contractors are much more likely to go the synthetic route that involves more soil amendments, gravel for drainage, and staking.
The organic method avoids this by building up healthy and balanced soil over a period of time. Certainly, this process takes longer, but the chemical way never gets it right; it just a crutch, and at times a toxic one.
This is not to say that one way is better than the other; its a personal decision. For example, Randy Lemmon who hosts the popular Garden Line radio show in Houston, Texas promotes the synthetic method. Randy is one of the best horticulturists and landscape engineers in south Texas.
On the other hand, Howard Garrett, known as the Dirt Doctor, is the top organic gardening and landscaping expert in Texas.
This article follows his suggestions for transplanting trees from the container to the yard.
Tree Planting Begins with Digging a Hole
As the Dirt Doctor says, dig an ugly hole. What he means here is the sides of the hole should not be slick and smooth like a spade or shovel might leave it.
Go ahead and chop into the sides if needed. The idea is that slick sides will inhibit root spread.
Its a good idea to either shovel the extracted soil in a wheelbarrow or on a tarp; this will make your life easier. How big should the hole be? At least as deep as the root ball is tall.
The sides should taper up at about a 45° angle and at the top it should be at least 3 times as wide as the root ball.
Almost all tree species like positive drainage. Howard recommends testing the hole by filling it with water and checking it the next day. If most of the water has not drained away, pick a higher location or consider installing a French drain
Place the Tree and Backfill with Native Soil
This is where Lemmon and Garrett really differ. Lemmon advocates adding soil amendments such as Tru-Gro (kiln-fired rocks, a concrete byproduct), Schultz Soil Conditioner, and Fertilome Natural Guard (also known as Revive). Garrett says this is a waste of money and suggests only adding some compost to the soil you dug up.
If your root ball comes wrapped in burlap, you can leave it on, but cut it away at the top. Remove plastic ties etc. Plastic container plants are easiest removed by just cutting down both sides and pull the root ball out.
Any roots that girdle the ball in container trees should be cut or straightened out. Place the tree in the center of the hole and backfill the soil to the top of the root ball. Do not tamp the dirt down.
Add Compost and Mulch
I like to toss a handful or 2 of dried molasses on the dirt at this point. Next, spread and inch of organic compost over the filled hole.
On top of this add a shredded hardwood mulch ring. It should not touch the trunk, but slope up to the high point and then angle out to the outside of the filled hole. At its highest point the ring should be about 4 deep.
Finishing up the Planting Job
Dont stake the tree unless its unavoidable. Dont prune any leaves or branches. The old concept that this must be done to compensate for cutting roots is just an urban myth. Do water it in thoroughly to remove all the air pockets.
Thats about all there is to it. Be sure to keep the soil moist until the transplant is established but dont overdo it.