By John Lookingbill, Colorado State Cooperative Extension Master Gardener, Denver County
Coloradans plant hundreds of young trees every spring, but many will not survive because they were planted improperly. Here are a few simple planting guidelines to increase the chances of successfully establishing trees.
Bare root trees must be planted in the early spring well before the leaves appear. Container-grown or balled-and-burlapped trees can be planted any time from early spring through early fall. These trees establish more successfully than bare root trees because they have more roots.
Probably the single biggest mistake in planting trees is burying the root ball too deep. In heavy clay soils, dig the planting hole only deep enough so the top 2 to 3 inches of the root ball remains above ground level. In sandy soil, the root ball's top can be even with ground level.
Planting trees at the correct depth is critical for positioning roots in top layers of soil where there is enough air for them to prosper. Dig planting holes wide rather than deep so roots will not be crowded.
Place the tree root ball on firm soil in the bottom of the planting hole, not on loose backfill. Backfill will settle and the tree will sink.
Plastic or metal containers must be removed before planting. Tear away other materials in which the root ball may be wrapped -- burlap, wood, tar paper or fiberboard -- after the tree is positioned in the planting hole. It's not necessary to remove material from the bottom of the root ball because 98 percent of root growth will be to the side. Remove wire, rope or string attached to the trunk.
Amend backfill, the soil removed from the planting hole. Add one part organic material, such as peat, compost or well-rotted manure, to two parts soil. Fill in the planting hole, but don't stomp down the soil. Instead, gently settle with water to avoid compaction and breaking roots. Insert a hose into the backfill and run water until soil settles; repeat at several locations around the tree.
Fertilizing at planting time is unnecessary and not recommended. Research at Colorado State University also has found that excessive top pruning at planting delays tree establishment. Prune only broken or dead twigs, and postpone major shaping and training of the tree for a year or two.
Do not overwater newly planted trees. Excess water displaces air in the soil that is needed for healthy root growth; it also leads to root rot. Check before watering by digging down 4 to 6 inches at the edge of the planting hole. If the soil is moist and forms a ball when squeezed, don't water.
If it is necessary to stake a tree for stability, use only flat, belt-like tree straps made of a soft material. Do not use wire threaded through a length of garden hose; this may result in girdling injury. Allow enough slack in the wire for some sway in winds. Movement in the wind promotes strong trunk development.
For complete information, refer to CSU Fact Sheet 7.417
Photograph courtesy of Connie Rayor.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010