TreeLines

By Dr. Austin Heine | Edited by Dr. Tom Starkey 

If you are planning to plant containerized seedlings this coming season, one important factor to consider is the time of year seedlings are planted. When site preparation is completed early and soil conditions are suitable, planting containerized seedlings in the fall can improve establishment success and encourage stronger early growth.  

Soil Moisture Matters 

The first consideration for early planting is soil moisture. Adequate soil moisture is critical for seedling survival, especially immediately after planting. Dry soils at planting are closely associated with higher mortality in planted pine seedlings, and planting is generally not recommended when available soil water is approaching or below 50% of field capacity (Long 1991).  

In recent planting seasons, some areas of the Southeast have remained too dry for successful early planting.  Even with the potential benefits of earlier planting, conditions still need to be right before moving forward. 

Fully Formed Root Plugs Are Essential 

Another key factor is ensuring containerized plugs have reached full cell capture. This means the root ball is fully formed and that it will stay intact throughout the handling and planting process. If the root system is not fully developed, the soil media can separate from the plug during planting, essentially turning the containerized seedling into a bare-root seedling.  

This is one reason it is important to contact your ArborGen Reforestation Advisor early in the season – ideally before sowing begins in January or February. Early coordination gives nursery managers time to ensure proper root development and schedule packaging crews at the appropriate time. 

The Ideal Window for Early Planting 

From my experience, the ideal window for planting containerized seedlings early is typically October through mid-November, with seedlings ideally in the ground before Thanksgiving.  

This timing allows seedlings several weeks to begin establishing roots before significant cold weather arrives. Planting too close to an extreme cold event can increase mortality risk, especially if seedlings are still actively growing. In most situations, allowing at least three weeks between planting and a severe cold event provides enough time for seedlings to acclimate and begin shutting down naturally in the field.  

Recent years across much of the Southeast have seen major cold events arrive during the first week of December, making planting timing especially important. 

What Research Shows About Early Planting 

While there are limited studies specifically comparing October and November container planting dates, research has shown that both containerized and bareroot seedlings planted in December achieved significantly greater height growth after two growing seasons than seedlings planted in February (Figure 1 from Figure 4.13 (Watson 2020)). 

Figure 1. Age two average total height for planting date by stocktype interaction in block plots for both planting dates across all study sites.  BR = bareroot, Cont = containerized. Values with the same letter do not differ statistically at the alpha = 0.05 level of significance.  From Figure 4.13 (Watson 2020).   

In addition to encouraging earlier root growth, early planting can help seedlings develop deeper root systems before spring and summer drought conditions occur. This improved root development may improve survival and long-term performance during stressful growing conditions (Bilan 1987).  

Planning Ahead for Early Planting Success 

Successfully planting containerized seedlings in October or early November requires planning well in advance. 

One important consideration is herbicide timing. Site preparation sprays involving imazapyr should generally be completed two to three months before planting seedlings. Specific recommendations for rates and planting intervals can be found in the University of Georgia guide (Dickens et al. 2020).   

The window for successful early planting is relatively short – often only four to six weeks. Because of this, it is important to line up planting contractors early and communicate your desired planting timeline well ahead of the season. Although suitable soil moisture cannot be guaranteed, having crews prepared allows landowners to take advantage of favorable conditions when they occur.  

What Happens After Early Planting? 

One major advantage of early planting is that seedlings can spend four to five months in the field establishing roots before warm spring weather arrives. Many people do not realize that pine roots continue growing throughout the winter, even while above-ground growth appears dormant.  

The following series of photos were taken in the fall of 2025 when containerized seedlings grown at ArborGen’s Blenheim nursery were being packed for planting on a landowner’s property in Duplin County, North Carolina. These seedlings were planted in mid-November 2025. 

Most areas were too dry to plant this past fall, but this particular location was not, as there was still standing water in the rows between beds at the time of planting. I visited the tract periodically from November 2025 through March 2026 and photographed both the seedling shoots and root systems so landowners could better understand what to expect as early-planted seedlings establish and develop through the winter months. 

Although the landowner called in January after several severe cold events moved through the area and was concerned that all of the seedlings had died, they had not. The foliage had turned reddish-brown to purple from the cold and wind exposure, but below ground, the roots were continuing to expand and prepare the seedlings for spring growth. 

Tracking Seedling Development Through Winter

Image 1. OP Pro containers being packed for planting on October 28, 2025. Note the extensive fine roots and mycorrhizal fungi present throughout the root system. Seedling foliage remains green, and root plugs are fully formed to hold soil media in place.  

Image 2. OP Pro containerized seedlings photographed January 9, 2026, after approximately two months in the field. Foliage has turned reddish-purple following significant cold events, but root systems remain healthy and continue growing. 

Image 3. OP Pro containerized seedlings photographed February 19, 2026, after roughly three months in the field. Buds are beginning to swell ahead of spring growth, while root systems continue developing below ground.  

Image 4. OP Pro containerized seedlings photographed March 19, 2026, after four months in the field. Warmer weather has triggered bud elongation, and foliage has returned to green as seedlings break dormancy.

Image 5. Root systems photographed March 19, 2026, showing significant winter root elongation and development of first-order lateral roots and fine roots that will help prepare seedlings for future drought conditions.  

Final Thoughts 

When conditions are right, early planting can give containerized seedlings a valuable head start heading into spring. Stronger root establishment, improved drought resilience, and earlier growth are all potential advantages – but success depends on proper planning, adequate soil moisture, and careful coordination with your planting team and ArborGen Reforestation Advisor. 

For landowners considering early planting this season, planning ahead now can help position your seedlings for long-term success. 

Literature Cited 

• Bilan, M.V. 1987. Effect of Time and Depth of Planting on Survival and Growth of Loblolly Pine (Pinus taeda L.) Seedlings in Texas. Faculty Publications. Paper 219.  

• Dickens, D., P. Minogue, D. Clabo, and D. Moorhead. 2020. A Guide to Using Imazapyr for Chemical Site Preparation in Southern Pine Plantation Establishment. University of Georgia, WSFNR-20-95B. 8p. accessible online at: https://bugwoodcloud.org/resource/files/18414.pdf 

• Long, A.J. 1991. Proper Planting Improves Performance. In: Forest Regeneration Manual. Kluwer Academic Publishers. 

Austin has been a crucial member of the ArborGen Reforestation Team for three years. Before becoming the Reforestation Advisor for North Carolina and Virginia, he worked with the NC State tree improvement cooperative for eight years.