Sweating Nursery Stock
Tree species such as hackberry, oak, and hawthorn exhibit deep bud dormancy and may fail to break bud after planting or have delayed bud break. This problem can be overcome by sweating the nursery stock. Sweating nursery stock should be done inside a building and out of direct sunlight. Put a sheet of plastic on the floor and cover the plastic with a layer of wet moisture retentive material such as sphagnum moss or shingletow. Put the seedlings to be sweated on the material and cover with additional moist sphagnum moss or shingletow. Repeat layers of trees and moisture holding material as needed. Cover with plastic and maintain temperatures of 50 to 70 degrees F. In this warm, moist environment bud swell should begin in 5 to 10 days. Stock can be planted outside when similar temperatures exist at the planting site. Do not sweat stock to bud break and then plant in conditions of sub-freezing temperatures or extremely dry soil conditions. For sweating to be successful, proper conditions of temperature, humidity, and soil moisture must be present at the planting site. Other species such as ash and amur maple stored for long time periods also benefit from sweating prior to planting.