As winter approaches your maples are losing their leaves, going dormant and preparing for winter. Typically maples can handle down to -15° F without much trouble, but when Japanese maples are young they may need some protection. The harsh effects from wind and ice are the two most important factors to keep in mind when protecting your trees. Here are some tips to consider for winterizing your maple if you live where there are particularly severe winter conditions.
1) Choose sites out of the wind as much as possible. You can minimize weather problems by picking a good planting site with stable temperatures. Planting near buildings helps stabilize temps – but look out for snow drop from roofs!
2) Do not fertilize into late summer. Make the last feeding of the season at least two months before you expect the first frost. Go light and use low amounts of nitrogen to limit damage to new growth.
3) Water heavily just prior to freeze-up. If autumn rains have been insufficient, give your plants a deep soaking to supply water to the entire root system before the ground freezes. Deep soaking will help to guard against water loss in winter.
4) Mulch to insulate the roots with a 3-4 inch-deep pile of mulch built around the base of the tree. Place the mulch 6 inches away from the trunk. Extend the mulch spread 2 to 3 feet beyond the drip line, (the tree's outermost branch). Make the mulch ring with dead leaves, bark, wood chips or compost. This keeps freeze damage to a minimum.
5) Wrap Japanese maples with burlap (if you experience heavy snows or prevailing winter winds) for at least the first three years. Snow falling in the colder climates can both protect and endanger plants. A good snow cover will insulate the soil similar to a mulch. However snow accumulating on Japanese maple branches will weigh them down, risking breakage.
To properly wrap your tree begin by preparing the smaller branches and twigs before they freeze and become brittle and prone to breakage. Tie one end of a rope around the base of the tree and encircle the crown of the tree with the rope from the bottom up, reaching as high as possible. Tighten the rope, pushing the branches close together. Cover the Japanese maple with a sheet of burlap from the top down. Fasten the burlap wrap with rope or heavy-duty duct tape. Alternatively, slip a burlap sack over the roped crown. Since your trees are small, it would be best to use a stake to help support the burlap. If your trees are in more exposed locations, wrap every year.
6) Leave potted maples outside until the temperature regularly drops to below 20° F, then protect by bringing them inside to a cold garage or under a porch close to the house. If any maples leaf out before the spring, put them under a grow light; but be careful when transferring them back outside because the leaves have to be eased into full-strength sun and weather.
7) Water only when they are almost completely dry. Maples do not need much water in the winter since they are dormant. There can be the tendency to overwater your maples in the winter and this can lead to root rot problems.
Winterizing your trees in cold climates can help ensure your tree’s survival through a harsh winter as well as help your tree get off to a great start in the spring.