By Janelle Daberkow
University of Minnesota Extension
Planting a tree seems simple. Dig a hole the size of the root ball, place the tree in the hole, and water, right? Not entirely. Here are a few tips for success for correct tree planting.
Remember, planting a tree is a long term investment, so the extra effort put into planting now, can alleviate headaches later.
First off, take special care when transporting plants from the nursery. The proper vehicle, a truck or trailer, can reduce the possibility of injury from loading and unloading. Protect leaves and needles from the sun and wind by wrapping or covering while in transit. Cushion stems and branches from injury.
Always tie the plants down securely and avoid high speed travel.
Successful planting starts with proper site preparation. Digging the hole for a new plant is the first step. The hole should be at least 1-2 feet wider than the size of the root system (except for direct tree spade planted trees). A larger hole will allow better root growth, especially in poor soil. Roughen the sides of the hole with a shovel and make the hole as wide as or wider at the bottom than at the top.
When trees are purchased, excess soil often covers their root system, in particular, the root collar (the area where the roots meet the trunk identified by flare in the trunk). This is not the fault of anyone, just an issue that is traced back to nursery practices.
While cultivating between rows of planted trees, nurseries often build up soil around the trunk of the tree. If this soil is not removed at planting time, trees can “suffocate” from excess soil covering their root system, resulting in a disruption of water and nutrient uptake, which starts a downward spiral for the tree. Planting trees too deeply also hides issues with tree roots such as encircling roots that can also suffocate trees.
To ensure your tree is not planted too deep, do not follow the common recommendation of planting the tree at the same soil level that was found in the purchased container or balled and burlaped tree. Search for trunk flare where the first set of roots are emerging from the trunk, then gently scrape away excess soil above this point to reveal the root collar. When planted at the proper depth, the root collar (trunk flare) should be visible. If the trunk enters the ground as straight as a telephone pole, the tree has been planted too deeply.
Other planting pointers:
• Dig the hole as deep as the root ball and no deeper so the soil under the root ball is undisturbed. This will prevent the tree from settling.
• Do not add soil amendments. Old recommendations for adding soil amendments such as peat moss have been discarded. Simply use the soil removed from the hole as backfill.
• Prune only broken or dead branches and roots at planting time. Removing live branches removes a source of stored energy important in overcoming planting stress. Start pruning for good structure in a year or two once the tree is better established.
• Stake trees only when needed as in windy or high traffic areas. Wire used for staking, even if protected with garden hose, can damage the trunk. Instead, use broad-banded materials. Check these stakes frequently and remove after one year.
• Wait a year to fertilize newly planted trees, and fertilize only if a soil test indicates the need for fertilization. Add 3 to 4 inches of organic mulch around tree roots, such as wood chips. Mulch should not contact the trunk. Mulch helps to conserve soil moisture, eliminates harmful competition from turf and keeps lawnmowers and weed whips from damaging the trunk.
• And, don’t forget the most important first step — selecting the proper tree. Avoid the “it’s so pretty” impulse purchase. Do your homework. Select a tree with the correct mature height and one that will easily adapt to the soil and planting site.
Do not wrap trees during the growing season. Tree wrap can hold moisture next to the trunk and serve as a home for insects. If rodents are a problem, use wire mesh cylinders around the trunk. Newly planted trees have a reduced root system in a small soil volume that will dry out quickly.
Specific advice for watering is difficult to give because of the variability of planting sites and soil types. The general rule is to keep the top 8-12 inches of soil of the rootball evenly moist. In most environments, this is equivalent to about 1 inch of rainfall every 7-10 days.
Watering more than this will do more harm than good. Periodically check the soil by digging down a few inches, and water only when the soil appears dry.
While the use of mulch around trees is suggested, and has gained in popularity, many people have gone overboard by heaping mulch “volcanoes” around trees. Instead of a “volcano”, make a “pancake”. Wood chip mulch should be 3 – 4 inches deep and care should be taken so that the mulch does not come in contact with the trunk.
For more resources on planting trees and tips for selecting the right tree for your location please visit: http://www.extension.umn.edu/distribution/horticulture/DG3825.html.