Setting out woody plants—whether shade or ornamental trees, privacy or flowering shrubs—is simpler than it used to be. Horticultural experts once recommended enriching planting holes with compost and other supplements. No more.
Those gardening gurus since have concluded that giving saplings overly cushy conditions is as much of a mistake as giving teenagers the same. If you make things too easy for them, you tempt them to “hole up” in their original comfy homes forever instead of stretching their roots into more challenging ground.
But you do want to allow your green young things time to establish themselves before tough times hit. Therefore, in colder climates, it’s generally best to set out evergreen trees and shrubs in spring, so they will have many months to begin growing up before winter blows in again.
In such frosty zones, deciduous trees and shrubs are the types most likely to tolerate autumn planting, since the falling of their leaves allows them to concentrate on root growth instead. And autumn often is considered the premier planting time in the south, especially in hot, dry zones where winter is the wet season.
In any case, wait until the ground has dried enough for the soil to be crumbly rather than compressed. Then spread a tarp or large sheet of heavy plastic near your intended site, so you can temporarily pile the removed loam atop it. Measure the size of your tree or shrub’s root ball, keeping in mind that most types should be planted at the same depth they grew in the nursery, so that the flare—the point where the trunk begins to slope outward to join the roots—is barely above ground level.
Exceptions to that rule include roses and tree peonies. In USDA zones lower than 7, roses should be set so their bud union (the graft or “knob” below the canes ) is 1 to 3 inches below ground level. In the other zones, that knob should be 1 to 1 1/2 inches above the ground.
For grafted tree peonies, bury the graft 4 to 6 inches deep. Own-root roses or tree peonies, knob-less because they aren’t grafted, can be planted with the top of their root ball 1 inch below the soil surface for roses, 2 inches below for peonies. (These instructions don’t apply to herbaceous and intersectional peonies, which aren’t included here since they are considered perennials rather than shrubs.)
For most other trees and shrubs, you should dig your hole as deep as the root ball and two or three times as wide. Water potted or balled trees or shrubs shortly before and after you plant them.
You then should ease your tree or shrub out of its pot, wrappings, or bucket. If completely detaching all of the wrappings on a larger specimen would be onerous, you usually can leave natural, untreated burlap or the lower part of a wire basket in place—as long as you pull the burlap back from the trunk and make sure it is completely covered by several inches of soil.
However, twine, treated burlap, or plastic wrappings such as synthetic burlap should be completely removed. For trees or shrubs which have become pot bound, use a sharp knife to score four 1/2-inch-deep equally-spaced vertical lines around the root ball. Then incise an X across its base and tease the roots outward.
When setting the tree or shrub in place, handle it by its root ball rather than its trunk. Mix in your soil amendments with the soil that you will be using to backfill the trees. We recommend Espoma Bio-tone, Roots Healthy Start & Juniper Farms Peat Moss. At this point, return the soil to the hole, packing it lightly around the roots, until that hole is about three-fourths full. After watering the returned loam thoroughly to settle it, complete your backfilling.
You then can use some of the extra soil to form a basin atop the planting hole, as wide as it is. This will allow you to funnel water directly into your tree or shrub’s root zone without most of it running off to the sides. Afterwards, apply a 2 to 3-inch layer of mulch to help retain the soil’s moisture.
You’ll probably need to water your newly planted tree or shrub frequently for the first couple weeks, unless you receive heavy rainfalls during that period. Gradually taper off that watering to what is normally necessary for your area. As with those teens mentioned earlier, trees and shrubs given a good start can grow strong—and at least reasonably independent!