Evergreens retain green foliage year-round, allowing them to photosynthesize even in cooler temperatures. This constant biological activity means they perpetually lose moisture through transpiration, unlike deciduous trees that enter true dormancy. Successful transplanting depends entirely on proper timing, ensuring the newly disturbed root system has adequate time to anchor and recover before facing environmental extremes. The goal is to maximize root development during periods when above-ground stress from temperature or water loss is minimized.
Ideal Planting Times for Root Establishment
The optimal period for planting evergreens occurs twice a year: in early spring and late summer into early fall. These windows offer a balanced climate that encourages root growth without excessive demands on the foliage. The early spring window begins as soon as the ground thaws and becomes workable, ideally before new buds break. This timing allows the plant to benefit from high natural moisture content from snowmelt and spring rains.
Planting in early spring gives the root system several months of mild soil temperatures to establish before summer heat and potential drought. The plant directs energy toward producing new feeder roots while cooler air temperatures limit water loss through the foliage. This abundant soil moisture makes the spring window favorable, especially in drier climates or for species prone to desiccation.
The second effective planting period is late summer, typically mid-August through early October, once intense heat subsides. Air temperatures cool, signaling the plant to slow above-ground growth and reduce water loss. The soil retains warmth accumulated over the summer, often remaining warmer than the air for several weeks. This combination of cool air and warm soil stimulates root generation.
This fall window provides an advantage because the plant naturally shifts its focus to root development in preparation for winter. By planting at least six weeks before the soil freezes solid, the evergreen can generate a robust network of new roots. A well-established fall planting is then poised for vigorous shoot growth the following spring, having already completed the stressful process of root recovery.
Why Midsummer and Deep Winter Planting Should Be Avoided
Planting evergreens during the height of summer, generally late June through mid-August, subjects the plant to maximum environmental stress. The combination of high air temperatures and intense sun drives a high rate of transpiration, causing the foliage to rapidly lose water vapor. Since a newly planted evergreen has a compromised root system, it cannot efficiently replenish this lost moisture, quickly leading to a state of severe water stress.
Midsummer soil is often hot and dry, inhibiting the growth of new roots needed for recovery. The plant diverts energy to survival mechanisms, such as closing stomata, rather than producing roots necessary for long-term health. This high-stress period increases the risk of transplant shock, potentially causing the plant to wilt, scorch, or die before establishment.
Deep winter planting, when the ground is frozen, presents serious challenges. When soil water turns to ice, the roots are physically prevented from absorbing moisture. Evergreen foliage continues to lose water vapor to the atmosphere, especially on sunny or windy days, leading to winter desiccation or “winter burn.”
This desiccation occurs because water lost from the needles cannot be replaced by frozen roots. Planting into frozen soil eliminates the critical establishment period required for root growth. Therefore, planting must be completed well in advance of the ground freezing to allow roots to develop a sufficient support system for winter water uptake.
Seasonal Adjustments to Planting Technique and Care
Aftercare for a newly planted evergreen must be tailored to the season to mitigate inherent risks. For fall plantings, the primary concern is ensuring the plant is fully hydrated before the ground solidifies for winter. Consistent, deep watering is necessary until the soil freezes, as a well-hydrated plant has greater reserves to resist winter desiccation.
Mulching is beneficial for fall plantings; a three- to four-inch layer of organic material insulates the soil, delaying the ground freeze and allowing longer root development. Avoid applying high-nitrogen fertilizers in the fall, as these encourage tender new shoot growth susceptible to winter damage. The plant’s energy should instead be focused on root production.
For evergreens planted in the spring, the focus shifts to monitoring for drought as temperatures climb toward summer. While initial spring moisture is helpful, the plant quickly requires supplemental watering since root establishment is in its early stages. Checking soil moisture regularly during dry spells is necessary to prevent water stress.
In both seasons, the goal is to provide consistent moisture without allowing the planting hole to become waterlogged, which can lead to root rot. Regardless of the season, a newly planted evergreen should receive approximately one to two inches of water per week, from rain or supplemental irrigation, for the first year.