Bare root trees are field-grown plants harvested during their dormant season, typically between late fall and early spring. These plants are supplied without any soil surrounding their roots, making them lighter and more cost-effective to ship and purchase. Storage becomes necessary when the trees arrive before the ground is ready for planting, such as when the soil is frozen, waterlogged, or when a gardener’s schedule requires a delay. The primary challenge is maintaining their dormant state while preventing the roots from drying out or freezing, which impacts the tree’s long-term survival.
Essential Conditions for Short-Term Storage
Short-term storage typically covers a period of a few days up to two weeks. Preservation of dormancy is achieved through precise temperature control, ideally kept just above freezing, in the range of 33 to 40 degrees Fahrenheit (0.5 to 4 degrees Celsius). Maintaining these low temperatures slows the tree’s metabolism and prevents the buds from breaking prematurely.
Moisture requires constant attention, as exposed roots are highly vulnerable to desiccation. Upon arrival, the roots should be inspected and immediately re-moistened if the packing material is dry. Original packing materials, such as damp shredded paper, peat moss, or sawdust, are suitable for storage if kept consistently moist but not soaking wet.
Suitable locations for this passive storage include a cool garage, a cold basement, or a refrigerator for smaller quantities of stock. The trees should be kept sealed in their original plastic packaging or placed in a plastic bag with the moist packing material to maintain a high humidity level around the roots. Avoid storing the trees near fruits or vegetables, as certain produce releases ethylene gas, which may harm the dormant trees.
The Heeling-In Method for Extended Holding
When planting must be delayed for more than a couple of weeks, the temporary active planting method known as “heeling-in” provides a safer, medium-term solution. Heeling-in is essentially a temporary planting that protects the roots and keeps the tree dormant for several weeks or even months. The goal is survival and root protection, not growth, so the process is performed while the tree remains dormant.
The site should be well-drained, sheltered from strong winds, and preferably in a shady area to maintain cool temperatures. A shallow trench is then dug, wide enough to accommodate the full spread of the roots and deep enough to cover them completely. For ease of covering and future removal, the trench often has one side sloped at a 45-degree angle.
The trees are removed from their shipping materials and laid at an angle in the trench, with the roots resting at the bottom and the main stem leaning against the sloped side. The roots are then completely covered with loose, well-draining soil, sand, or compost, ensuring that all air pockets are eliminated. The root collar remains at or slightly above the temporary soil line.
Immediately after covering, the heeled-in area must be thoroughly watered to settle the soil and establish good contact with the roots. The soil must be checked periodically and kept moist, preventing the roots from drying out, which is the most significant danger to bare root stock. When the time comes for permanent planting, the trees are gently lifted from the trench, taking care not to damage the newly established fine root hairs.
Assessing Tree Health and Maximum Storage Duration
The maximum time a bare root tree can be stored depends on the species, its initial health, and the consistency of the storage conditions. Under ideal cold storage conditions (33 to 35 degrees Fahrenheit and high humidity), some commercially stored trees can remain viable for up to six months. For a home gardener, storing trees for more than one to two weeks is risky, and heeling-in typically extends the safe period to approximately six to eight weeks, or until the tree naturally breaks dormancy.
Before planting, check the tree’s viability using the “scratch test.” This involves gently scraping a small section of the outer bark on the trunk or a branch. A living, healthy tree will reveal a bright green layer of tissue, known as the cambium, just beneath the surface.
A brown or dry layer indicates dead tissue in that section, though the test should be performed further down the trunk until green tissue is found. The roots should also be assessed by bending a few of the smaller, fibrous roots; a viable root will be flexible and white inside. A dry or dead root will be brittle and brown or black.