Horticulturist, Member Horticulture Committee
The Crape Myrtle Trails of McKinney
Site Selection: Crape myrtles must be in full sun (at least 6 hours daily) to bloom to their maximum potential. Allow ample space for the mature height and spread of the selected crape myrtle variety: a few feet for miniatures and as much as 25 feet for the larger varieties such as Natchez or Muskogee. Pay particular attention to the distance from the house or other structures, which should be no less than half the mature width of the crape myrtle, preferably greater.
Transporting Your Crape Myrtles Home: Gardeners buy most of their crape myrtles in summer, while the plants are in full bloom. That’s a good way of ensuring variety purity and getting exactly the shades that you want. However, it also requires that you protect their foliage and flowers from highway winds on the way home from the nursery. Wrap them in old sheets, used nursery shade fabric, burlap or some other protective covering. There is absolutely no way you can drive home slowly enough to prevent serious damage to the leaves and blooms so don’t even try. If you are carrying the plants home in an enclosed vehicle do not stop in transit. Unload them immediately. Set them temporarily into a shaded location and water them deeply. Secure their trunks as you carry them, to be sure they do not rub or break.
Planting Hole: Dig the hole two to three times as wide, but no deeper than the height of, the root ball (not the container depth). In heavy clay soils where drainage can be a problem, it is helpful to dig the hole 1 to 2 inches shallower than the root ball so that the planted tree will end up slightly above the surrounding grade. Be sure the sides and the bottom of the hole are not “glazed,” that is, smoothed and compacted from the digging. Glazing forms a barrier that retards the passage of water. It is particularly likely to occur when digging in damp soil. Use a digging fork on the sides and bottom of the hole to roughen and break the glaze if necessary.
Setting the Tree: Always handle trees by their root balls, never by their trunks. Handling them by their trunks can break the roots away from the trunks, which means almost certain death. Lay a large container crape myrtle on its side and slide the pot away from the moist root ball rather than pulling the tree from the container by its trunk. Small container trees can then be set into their planting holes. If they are too heavy to be lifted safely they can be rolled into their planting holes. Set balled-and-burlapped (B&B) trees in the same way, lifting by the root balls, not the trunks.
Check the position of the tree before you start filling the hole and straighten your new crape myrtle as necessary. Replace some of the soil removed from the planting hole (backfill) to steady a B&B tree and then cut away the wire and/or twine and burlap. Be especially careful to remove all twine wrapped around the base of a tree-form crape myrtle (the neck of the burlapped ball), as it will eventually girdle and kill the tree if left in place. If the burlap on the root ball is synthetic, it must all be completely removed, as it will not decay. If it is natural burlap, it may be removed from only the upper third of the root ball. It can be cut away or folded back into the hole, although removing that portion is preferable: burlap left on the root ball and extending above or just under the soil can wick water from the root ball, causing the root zone to dry excessively. University studies have demonstrated that wire or twine on the lower two-thirds of the root ball do not inhibit root growth, so the wire or twine wrapping the root ball should be removed from the upper third of the ball, but may safely be left on the lower portion.
Backfill: Soil amendments are not recommended when planting tree-form crape myrtles. Trees should be planted in the soil in which they must grow, so only the soil dug from the planting hole should go back into the hole. Backfill the planting hole to the original grade, breaking up any clods and gently tamping the soil as the hole is filled. Don’t compact the soil. On the other hand, don’t fill it so loosely that the root ball is not supported. When the planting is complete, construct a low berm or “water ring” 3 to 4 inches high and wide around the edge of the planting hole. Gently smooth it with the back of the shovel or with a garden rake.
Dwarf types of crape myrtles are usually planted into landscape beds, so some degree of soil amendment will probably be done. If you do for these small varieties the same things you would do for a bed of another type of low shrub or groundcover, your crape myrtles should be well satisfied.
Water: After planting, water your new crape myrtle thoroughly to settle the soil around the root ball. Fill the basin created by the berm, let it settle and repeat two or three times. The size of the plant and the type of soil will dictate how much water is needed, just as it affects long-term water needs. Large plants will obviously need more water than small ones, although small plants will probably need water more often as their root systems are smaller. Likewise, balled-and-burlapped root balls, which typically have more clay, will absorb and retain water longer than loose, porous container root balls. Once established, crape myrtles in sandy soils will need water more frequently than those in clay soils.
Mulch: Fill the berm with mulch (shredded bark, compost, pine needles, etc.) which will help with moisture retention and reduce competition from weeds. The mulch layer should be 2 to 4 inches deep. Do not place mulch directly against the trunk. Keep it about a finger’s width away.
Maintenance: Allow the berm surrounding the root ball to erode over the next season or two. It is not necessary to maintain it once the tree is established. Continue to maintain a 2- to 4-inch layer of mulch over the root zone, particularly if you have a tree-form crape myrtle that is located in a lawn area. Not only will the mulch moderate root-zone temperatures, retain moisture longer and reduce weeds, but it will also eliminate the need to mow or use string trimmers near the trunk. Mechanical injuries are common causes of tree decline, particularly in intensively maintained landscapes. Line trimmers are trees’ mortal enemies. You will see damaged and scarredtrunks in many landscapes.