Thuja is a commonly found coniferous tree with a limited number of species, but it boasts a wide range of decorative varieties. Because of its popularity among gardeners, especially beginners, many are curious about the ideal time to commence its growth.
The optimal period for planting Arborvitae is during the first half of autumn or early spring. During these seasons, the sun’s intensity is relatively mild, and overall conditions are more favorable, making it easier for the plant to establish itself.
While this answer provides a concise overview, as with any horticultural endeavor, there are numerous subtleties and nuances to consider. Let’s delve into these details more comprehensively.
Planting arborvitae in fall
The optimal period for planting is early autumn, typically spanning from late August through September and early October. During this window, potted plants can be safely transferred to the ground.
For those residing in northern regions, late August or early September is ideal. If you’re in Hardiness Zones 5-8, mid-September is a suitable timeframe. In southern areas, late September to early October is recommended.
The key is to align with favorable conditions. In the first half of autumn, the sun’s intensity decreases compared to summer, reducing the plant’s need for frequent watering. Additionally, autumn tends to be a wetter season, minimizing the risk of plant dehydration.
Furthermore, the soil retains warmth in autumn compared to spring, promoting faster root development.
Another crucial factor for success is ensuring an adequate buffer before the first frost arrives. It’s essential to plant at least 30 days prior to the anticipated frost date, as this allows ample time for root establishment.
Planting arborvitae in spring
The next favorable season for planting Thuja is spring. By March, temperatures have sufficiently warmed, making it an ideal time to transplant Thuja from pots to the ground. For those residing in the southern states, late February is a suitable timeframe, while in the northern United States, this can extend to the end of March or early April.
A fundamental requirement is that the soil must not be frozen, and it’s advantageous if the plant is still in a dormant state, without the onset of sap movement.
Spring planting offers the advantage of nurturing young growth. These fresh shoots have high demands for moisture and nutrients, which in turn promote robust root system development.
Planting arborvitae in summer
Summer is generally not the most suitable season for planting conifers, and while many nurseries suggest it’s possible to transplant Thuja from pots during the summer, I have some reservations about this practice based on my experience.
In my observation, a significant number of trees planted during the summer don’t thrive, and some even fail to survive. While not all plants face this outcome, the risk of losing a plant certainly increases in the summer.
The primary reason for suboptimal root development during summer planting is the combination of excessive sunlight and inadequate moisture. When you plant Thuja from a pot in the summer, it experiences a burst of growth but struggles to establish a robust root system to supply the necessary water. The intense sun exposure can further contribute to drying out the plant.
While it might seem that frequent watering could address this issue, it’s not quite that straightforward. Maintaining consistent moisture levels in the soil can be challenging. Overwatering is a concern if you provide infrequent but excessive amounts of water. It’s more practical to water more frequently but with smaller quantities, although this can be somewhat labor-intensive.
If you’re determined to plant Thuja in the summer, consider doing so in early or late summer. Late August, for instance, is a more favorable timeframe, even surpassing spring planting for those in the northern United States. Additionally, if possible, provide some shade for the plant until the arrival of autumn to mitigate the effects of intense sunlight.
Winter is the second unfavorable season for planting Thuja, primarily due to the obvious factor of frozen soil. While I have successfully planted Thuja during winter on a few occasions, I generally do not recommend it.
For one, if you transplant a Thuja from a pot into the ground during the winter and encounter severe frosts, the soil’s pressure can potentially harm the delicate roots, leading to the risk of root rot. Since the plant is dormant during this period, it lacks the ability to heal wounds, increasing the likelihood of its demise.
Furthermore, winter typically brings higher humidity levels. Planting Thuja during this time might hinder its adaptation to new conditions, potentially resulting in root rot.
If you lack experience, it’s advisable to avoid planting in winter altogether.
Additionally, I discourage the practice of replanting Thuja in winter. Damaged roots are susceptible to rot during the winter months, and this can lead to the loss of the plant. If you must consider replanting during the winter, the end of February is a more suitable timeframe.