Hi! I have some tree saplings that I’m starting in containers with the intention of transplanting to viable sites when they are a little older and stronger.
How do I protect them in the winter? Particularly, should I be worried about soil freezing/watering?
Hi Sameera – The best protection for your tree saplings is dependent on the type of trees and the size of your containers but here are some general suggestions.
If you have the space and your containers aren’t too large you could bury them temporarily, container and all. Cover the area with a thick layer of leaves and/or mulch.
Deciduous saplings can be moved into an unheated garage or shed once they lose all of their leaves and go dormant with the early frosts. This approach isn’t appropriate for evergreens which require some sunlight during the winter months.
Another option, particularly for evergreens which require some sunlight during the winter months, is to group your trees in a protected spot, away from direct sun and wind. A layer of mulch on top of the container is helpful but avoid piling the mulch against the trunk. The mulch may hold moisture against the trunk which can cause rot. Building an enclosure around the containers (for example, with chicken wire) and then filling the enclosure with leaves or straw up to the top of the container can help to protect container plants from the coldest winter temperatures and help to moderate the freeze-thaw effect.
Keep watering your containers until a hard freeze. This is particularly important if your saplings are evergreens as their needles continue to transpire during the winter. You shouldn’t have to water them over the winter while the trees are dormant except for periods of thaw. One gardener I know adds snow when available to the containers he stores in his garage. If the temperature warms enough to melt the snow, the containers are watered.
I’m including links below to two articles on growing and overwintering trees in containers. The articles are focussed on situations where the trees are being grown permanently in containers but they may give you additional useful ideas.
I hope you have good success with your saplings.
June 30, 2021