Storage Facilities

Storage facilities include the heel-in bed, cool garages, root cellars, and various refrigerated units.

The heel-in bed is used regularly at the State Nursery for over-winter storage of dormant hardwood seedlings with very good results. Use of the heel-in bed in spring can only be a short term solution because higher temperatures and longer day length will be affecting the seedlings.

Ideal storage conditions can be found in refrigerated units that range from 33 degrees to 35 degrees Fahrenheit with a 95 percent relative humidity. Seedling respiration increases rapidly above 40 degrees Fahrenheit, depleting valuable reserves of moisture and carbohydrates.

Freezing temperatures for over-winter storage is being used successfully for some species. This practice is something for us to consider at the nursery, but probably has no application at the field end of the process as frozen trees must not be roughly handled and must be thawed slowly.

Moisture stress retards growth in storage and is used in some nurseries to keep fruit trees dormant. This is also why soaking the roots of this type stock overnight sometimes helps. This is not practical with our stock, nor is it necessary.

Some districts in North Dakota have handled the storage problem by freezing ice on the floor of a building during winter and covering it with straw. The trees are placed in the building in the spring, and the melting ice keeps it cool.

Mold on trees can sometimes be a problem when storage conditions have been less than adequate. Cold storage usually prevents severe mold problems; but once molds have started in tree bundles, they should be opened to better air circulation immediately, such as in a heel-in bed or planting. Moderate amount of white mold on the surface can be washed free of the trees; but once the black molds have penetrated the tissue, the trees probably will not recover. Closed containers used for tree shipments can sometimes develop inside temperatures 12 degrees higher than the outside of the bags. This is particularly true with active trees and storage temperatures above 40 degrees Fahrenheit. Close attention should be given to temperature and possible mold development.

< Back to Transportation, Care, and Storage of Seedlings; and Planting

Last Modified: 07/05/2007