Understanding bare-root trees and shrubs
Early spring between the time the ground thaws but before the buds break is one of two optimal times during the year for planting bare-root trees and shrubs. Autumn is a second good time to plant. Soil temperature and moisture levels encourage active root growth. Lower air temperature and dormant crowns also help minimize transplant shock.
What are bare-root plants? Bare-root are nursery stock trees and shrubs that are field grown for one to three years, undercut and dug in the fall and spring, handled with no soil left around the roots, and stored with the roots moist and dormant tops at a temperature a few degrees above freezing until they are planted.
Some advantages for choosing bare-root:
Bare-root are usually half to two-thirds the cost of containerized or balled and burlap plants, because bare-root is easier to handle, store and ship.
A longer root length is possible since the weight of the soilless root ball is minimal.
The entire root system can be inspected so deformed, circling and broken roots can be detected and corrected or removed.
The appropriate planting depth is easy to gauge since root system is visible.
Because there is no soil around the root zone, there is no dramatic change in soil interface between rootball and native soil that can hinder plant establishment.
There are also some disadvantages to bare-root:
The range of plant size is usually a 2-inch caliper or less (the diameter of the stem measured 6 inches above the ground). Evergreens are not sold as bare-root unless they are very small seedlings.
Bare-root should be dormant when planted so there are seasonal restrictions.
The exposed root system cannot be allowed to dry out during handling, transporting or planting, so special caution should be taken from exposer to sun and wind.
If you cannot plant the bare-root immediately, put it in a cool, shaded, sheltered location and cover roots with moist straw, hay, damp burlap or loose moist soil.
Bare-root trees and shrubs lose up to 95 percent of their root system when they are undercut and removed at the nursery. After planting it is hard for the reduced root systems to absorb enough water to meet the needs of the plant. Until the root system grows and reestablishes itself to normal size, trees and shrubs experience transplant shock, which is primarily drought stress. Bare-root need to be planted and cared for in a way that provides optimal environment for root growth and replacement during the first years after transplanting.
The hole for planting should be as deep as the root system height. The width at least two to three times as wide as the root ball to allow rapid root growth through the backfill area before hitting the growth-slowing compacted soil surrounding the hole. It is for this reason it is better to use the original backfill soil and make the hole wider to allow rapid root growth, than to dig a narrow hole and add amendments to improve the soil.
How long does it take bare-root to reestablish themselves? It depends on genetics, environmental factors and tree size. A rule of thumb is to assume that it will take 1 1/2 years for each inch of stem caliper. So a 1-inch caliper tree will replace its root system in one and a half years, while a 2-inch caliper tree will take about three years.
A 3-inch layer of mulch under the canopy of a tree or shrub eliminates competition for water and nutrients from grass roots. Mulch will suppress weeds, retain soil moisture, buffer soil temperature, protect stems from mechanical injury and add organic matter to the soil. Mulch however, should not come in contact with the stem or trunk and should be pulled back a few inches around the trunk.
Leave as much of the crown intact as possible. Prune only to remove diseased, dead, broken, crowded or rubbing branches. This will maximize photosynthate production to promote root and trunk diameter growth.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.