Evergreen trees, which include both needle-bearing conifers like pines and spruces and broadleaf varieties such as holly and rhododendron, present a unique challenge when transplanting. Unlike deciduous trees that shed their leaves and enter a true state of deep dormancy, evergreens retain their foliage year-round. This continuous presence of needles or leaves means the tree is constantly losing moisture through transpiration, even during colder months when the ground may be frozen. Successful relocation requires precise timing to minimize moisture stress and allow the root system to recover before being subjected to environmental extremes. Understanding the right window for moving these trees is paramount, as poor timing can result in significant desiccation and failure to establish in the new location.
The Optimal Transplanting Windows
The most successful times for relocating evergreen trees fall into two distinct periods when temperatures are moderate and metabolic activity is reduced. The first window is in the early spring, immediately after the ground thaws but before the tree begins new growth. This timing allows the roots the benefit of the entire upcoming growing season to establish themselves in the new soil before the stress of the next winter arrives.
The second optimal period occurs in the late summer or early fall, typically from late August to mid-September, depending on the region. Transplanting during this time allows the roots to continue growing in the still-warm soil while above-ground canopy growth has slowed down. This window must close at least six weeks before the expected date of the first hard freeze, as the tree requires substantial time for root re-establishment before the soil becomes too cold. In colder climates (USDA Zones 3 and 4), early spring is safer, while in warmer zones (8 and 9), transplanting can occur anytime between early fall and early spring.
Why Timing is Critical: The Role of Dormancy and Root Shock
Transplanting success hinges on moving the evergreen when its physiological processes are operating at their lowest rate, a state known as dormancy. Evergreens do not experience the complete dormancy of deciduous trees, but their metabolic activity slows significantly in cooler temperatures, reducing the demand for water and nutrients from the root system. This reduced demand minimizes the impact of root shock, a severe stress response that occurs when a tree’s roots are damaged or lost during the move.
Root shock results from the disruption of fine feeder roots, which are responsible for water and nutrient uptake. When the tree is moved, a large percentage of these roots are severed, drastically limiting the tree’s ability to absorb moisture. By transplanting during the dormant period, the tree’s reduced water loss through transpiration better balances the compromised water uptake capability. The goal is to minimize the gap between the damage inflicted on the roots and their subsequent recovery, which is best achieved when the tree is not actively growing above ground.
Specific Timing Conditions to Avoid
Transplanting evergreens during periods of environmental stress should be avoided to prevent tree failure. The most hazardous time is the middle of summer, particularly during periods of high heat and drought. Moving a tree when temperatures are elevated and the air is dry causes immediate and severe desiccation because the remaining foliage continues to transpire rapidly. The damaged root system cannot supply enough water to compensate for the extreme moisture loss, leading to rapid wilting and tree death.
Another unsuitable time is deep winter when the ground is heavily frozen. Although metabolic activity is low, attempting to dig a root ball from frozen soil causes significant damage to the roots. Furthermore, a newly planted root ball in frozen soil cannot settle or draw moisture, leading to a condition known as “winter burn” or desiccation. The tree’s roots remain dormant and unable to function, making it impossible to replace the water being lost through the needles due to winter winds and sunlight.
Pre- and Post-Transplant Timing Considerations
Successful transplanting requires carefully timed actions both before and immediately after the move. For established evergreens, preparatory root pruning should occur six to twelve months prior to the actual transplant. Pruning the roots encourages the tree to develop a dense, fibrous network of feeder roots within the area that will become the new root ball. This step improves the tree’s chance of survival by ensuring more water-absorbing roots are moved with the tree.
The final preparatory step is to thoroughly water the tree one to two days before the scheduled transplant. This ensures the root ball is fully hydrated, which reduces stress during the move and helps the soil hold together. Immediately following the planting, the tree must be watered deeply to settle the soil around the root ball and eliminate air pockets. Consistent watering is then required for the first six to twelve weeks post-move, regardless of the season, to keep the root ball moist and encourage new growth. Applying a two to four-inch layer of organic mulch around the base of the tree helps regulate soil temperature and conserve moisture.