Planting trees in cold and wintry conditions

Planting and transplanting trees requires awareness and skill. During frosty and snowy weather, there are also additional things to consider in order for a newly planted tree to thrive. Soil conditions, protection of the roots, correct watering and insulation of the tree are crucial in order to prevent frost damage and to encourage root growth so that the tree can flourish. This article provides some useful tips since the winter months are the most important season for planting trees.

November through to March is the ideal planting time for trees. This is when they are dormant, thus minimising any disturbance of the growth process. This makes it easier for trees to get established. In addition, the soil is often moist and there are fewer diseases and pests active. If the temperature falls below zero for an extended period, the conditions for planting trees change however. Frozen ground can make planting difficult because the roots are unable to properly get established and water absorption is restricted. What’s more, extreme cold can damage the roots if they are not properly protected.

Six important points to consider when planting in frosty weather or snow

1. Soil conditions: It is essential to check if the ground isn’t frozen. Frozen ground makes it difficult to dig planting holes and impairs root development. The trees themselves are also frozen and can get damaged more readily. It is best to plant whenever the soil is still workable, even if the air is cold. If there is only a short period of slight frost, planting is then possible but, in this case, ensure that the frozen earth is not used to fill around the planting hole. If the layer of frost can easily be penetrated with a spade, it is fine to do some planting. Also avoid any planting in very wet soils or getting planting holes full of water. Due to a lack of oxygen in the soil, the emerging tree roots will die off and there is a great likelihood of the plant failing. Frosty conditions can however make planting on wet or still loose (turned) soils a possibility. This allows you access to places, using heavy machinery, where this is not possible without frost. Be sure to stick to the above measures to prevent frozen earth or snow from getting into the planting hole.
   
   
2. Protection of roots: Bare roots must not be exposed to cold air for very long to prevent them drying out or freezing. It is important to get trees with bare roots into the ground quickly and to protect them against cold during transport. Covering rootballs with straw, leaves or hessian bags are good solutions to protect them from the weather. Rootballs can also freeze of course. You can cover these with hessian bags, old blankets, straw or leaves. Often just the outside edge freezes and the rootlets deeper in the root ball stay protected, thus allowing them to develop properly still in the spring.
   
   
3. Watering: To ensure that the bare roots make good contact with the soil, it is advisable always to water after planting. This also prevents air spaces from occurring around the root system. Ensure that the soil does not dry out completely before winter really sets in. Concerns in relation to drying out are greater when it comes to bareroot plants. The fine rootlets soon dry out and will then quickly die off. The plants are capable of producing new roots but drying out of the roots must be averted as much as possible. During frosty weather the roots can also break easily, which means the plants will be slow to get established in the spring.
   
   
4. Insulating the tree: Mulching around the base of the tree helps to keep the soil temperature stable and protects the roots against extreme cold. In the winter in particular the newly planted tree will benefit from a top layer of mulch. This layer of organic material provides good insulation. It inhibits evaporation from the soil and protects against penetrating frost in the ground, in a natural way. A further benefit is that it suppresses somewhat the emergence of weeds in the spring.
   
   
5. Planting depth: Ensure that the tree is planted to the correct depth, with the root collar at or just above the surface of the soil. In winter, a tree that has been planted too deeply may suffer more from standing water and freezing. Determining the correct planting depth is very straightforward. Once planted, the top of the root ball should be level with or slightly higher than the ground. For freshly tilled ground, you must also be aware that the root ball may subside afterwards thanks to the earth settling. It is preferable to plant too high than too deep.
   
   
6. Snowy conditions: During snowy weather the ground is often not frozen or only just. The planting hole must first be cleared of snow. If you intend to do some planting in the snow, you need to stop snow from getting in the planting hole because the roots will then freeze and die. Indeed, snow remains insulated in the ground which means that the soil does not warm up well and roots do not develop. Dig the planting hole shortly before planting. This is to prevent the entire planting hole from freezing.

By taking these factors into account the tree can be planted successfully, even in cold conditions. Not sure? In that case, it is better to wait until the temperatures rise above freezing so that the ground is workable again and the tree has a better chance of growing well.

On balance, cold and wintry conditions do not need to pose a problem when it comes to planting trees on projects. During a severe frost, it is advisable to give the trees additional cover and if at all possible, to postpone the work. For a number of varieties of evergreens it is essential to plant early in the spring or at the end of autumn using freshly lifted plants. Therefore, it is a good idea to contact the nursery early on or advise them on the project implementation date. Planting during a severe frost would be highly inappropriate.