Proper tree planting is essential to long-term tree survival, health, and safety. Planting trees seems like a simple task, but if a tree is to thrive and not just survive, you must plan ahead and follow up with diligent care. The establishment process begins with the selection of good planting sites and appropriate tree species and varieties. Prepare sites, purchase and plant trees, and schedule regular maintenance for at least three years or until trees are established and growing well on their own.
Planting the wrong tree in the wrong place or planting a tree improperly can easily lead to hazardous or simply dead trees and wasted landscaping or maintenance budget. Choosing the right site, the right species, the right tree specimen, and the right planting method will ensure that any tree you plant will become an asset to the landscape, not a liability. Think of the tree you plant as an investment in the future.
When to Plant
The best time to plant a tree depends on the climate where you live. When planting deciduous species, the ideal time is usually during the dormant season when there are no leaves on the tree. In the Pacific Northwest, this is generally between November and April. Avoid planting trees when the ground is frozen or during hot, dry weather.
Prepare the Soil
Call your local utility locating service before you dig. Always locate utilities prior to planting trees in any site.
Break up compacted soils in an area five to ten times the width of the new tree’s root ball or container. Dig a planting hole that is at least twice the width of the new tree’s root ball or container; more is even better. A large hole will allow better root growth and is especially important in compacted soils. The graphic shows the importance of digging a big enough hole to allow the roots to extend out into the soil around the planting site.
Planting depth is of critical importance. Trees are often planted too deep in the hole. Nearly all trees have a root collar – a flare or bulging area where the tree trunk meets the root system. If you can’t see the root flare, the tree may be planted too deeply, which can deprive the tree of oxygen and make it more susceptible to root disease. The depth of the planting hole should be no more than the height of the root ball from its base to the bottom of the root collar.
Support the root ball with your hands and gently place the tree in the hole to test for proper depth. Never drop the tree on the ground or in the hole as this disturbs the root ball and can break the roots. Take care not to loosen or break the soil ball.
Roughen the sides of the hole, which should be the same width at the top and bottom, and remove any rocks or debris.
Never use lawn fertilizers in a planting hole. Contrary to popular belief, you don't need to fertilize trees when you plant them. Do not add soil amendments such as peat moss to the planting hole; studies have shown no benefit from these expensive practices. However, you can use a well-balanced (for example, a 10-10-10 formulation), slow-release fertilizer in the planting hole. Slow-release fertilizers have a long-lasting effect and are less likely to burn the roots. Other fertilizers can accentuate transplant shock.
Prepare the Tree
Once the hole is the proper depth, remove all tags, wires, string, straps, burlap, and wire baskets from the root ball and trunk. If the fabric will naturally degrade, you may instead choose to pull or cut away at least the top third. Containerized trees often have roots growing around the inside of the container. After removing the container, gently straighten the roots to avoid girdling root problems.
Planting and Backfill
If it is a bare root tree, mound some soil in the center. Set the root mass on top of this mound so the roots cascade downward in each direction.
If you plan on staking your tree, drive two wooden or metal posts along the sides of the hole before you backfill. This prevents you from accidentally driving the stakes through the root ball and damaging the root system.
Backfill the planting hole with the original soil, about one-half full, and lightly tamp it with your foot to remove any air pockets. The soil should be firm around the trunk, but don't pack the soil tightly. Make sure the tree is standing upright and not leaning. Water slowly to saturate the soil and remove any remaining air pockets, then finish filling the hole with soil. The root collar should be at ground level or slightly higher - do not bury it. Complete the planting by watering again to lightly compress soil around roots and eliminate air pockets. Do not mound extra soil around the tree.
It's important to make sure your young tree doesn't dry out. Unless soil conditions are very wet, build a temporary berm, or ridge, out of leftover backfill soil at the drip line - the edge of the tree canopy. Use this berm to hold water around the root system. Remove this bermed watering ring after one year.
Young trees, not unlike young children, require significant care for the first few years of life.
Mulch around the tree to avoid soil compaction and root suffocation. Add coarse organic mulch in the watering ring to a depth of four to six inches to conserve water and keep the root zone cool. Do not let mulch touch the tree trunk.
If the tree is planted in a high traffic area, will be exposed to high winds, or is unable to stand upright on its own, you may wish to stake it. Generally, you don't need to stake trees. Young trees standing alone with their tops free to move will develop stronger, more resilient trunks than tightly staked trees. However, too much wind can bend young trees and disturb the root ball, damaging roots and stressing the new tree. Staking helps trees that are top-heavy and would lean without additional support. Staking also helps protect trees from vandalism and mechanical damage.
Staking should take place during planting. To properly stake a tree, you need two wooden or metal posts. Drive them into the sides of the excavated planting hole before you backfill to prevent driving them through the root ball. Secure the tree to the stakes with broad straps, hose, soft rubber links, or other stretchy, non-abrasive materials. Wire should not be used as a guying material; even enclosed in tubing, it tears the thin bark of young trees and may girdle the tree as it grows. Guy and stake the tree so it is secure from blowing over, but allow the trunk to move up to two inches in any direction. If staking doesn't allow some movement of the tree's trunk, the tree will not grow correctly, and it will be unstable when you remove the stakes and guying.
Staking can cause abnormal trunk growth and bark damage, so remember to remove the stake and guying materials within a year.
If wind is the concern, an alternative to staking are wind barriers made of plastic or cloth. This will allow the tree to remain upright while it is developing its root system. As with stakes, remove wind barriers within a year to avoid unusual weakness in your tree.
Schedule Ongoing Maintenance
Maintaining a tree in a healthy condition requires periodic inspection and tree maintenance activities such as watering, pruning, mulching, fertilization, and plant health care. This is especially important during the first three to five years of life. If you are not certain about what is best for your tree, an ISA Certified Arborist can help you with your new tree. ISA Certified Arborists are not only knowledgeable about trees’ needs but also trained and equipped to work with trees in a manner that is safe for both person and plant.