Winter Care of Thuja Green Giant

Thuja Green Giant is the most popular hedging plant in America, except in the coldest areas, where Emerald Green Arborvitae is a better and hardier choice. Although Green Giant is completely hardy throughout Zone 5 – that is, where winter minimums can reach minus 20 degrees Fahrenheit – if you do live where it is close to its minimum hardiness, there are some simple steps you can take to protect your plants from potential injury, especially if some exceptionally cold weather should come your way. These few simple steps will give you ‘top-up’ insurance on your plants, and make sure they come through the winter untouched, and looking as great as ever. Of course, if you are in a warmer area, these steps will be completely unnecessary, because this is a tough plant, adapted to grow well across a large part of the country, with no special care at all.


It seems odd to suggest watering trees in late fall, when the temperatures fall, but for evergreens this is a vital time when water is very important. Especially following a dry summer and fall, the ground may not be fully saturated with water. This is especially true around the base of a hedge, where the thick foliage can prevent rain penetrating right down to the roots. When the ground freezes it becomes harder for trees to draw the water they need, and this can lead to problems. The foliage continues to lose water, especially when cold, dry winter winds blow, and if that water cannot be replaced, the foliage can wither and brown.

Thuja Green Giant is normally resistant to this kind of burning, but it makes sense to take the little time needed, and give your hedge a good soak before the ground freezes hard for the winter. This is especially true for newly-planted trees, whose root-balls have only limited access to water, since the roots have not yet spread out. If the ground is saturated when it freezes, it will not freeze so hard or so deep, and the roots of your trees will still be able to get all the water they need, and brown foliage will never strike your plants.

If you have a soaker hose in place for regular watering, this job is as easy as turning a tap on for a few hours. If you don’t have a hose in place, then moving a trickling hose along the hedge, leaving it in each spot for an hour or two, doesn’t take much effort either. A slow flow of water for a longer time will penetrate much deeper than a fast flow for a short time.

Screen Young Plants

The first winter in the ground is an important stage in the life of your Thuja Green Giant plants, and in cold areas a little extra care will be well rewarded. If your new hedge is in a position exposed to strong northerly winds, or along a highway, then a simple screen of burlap attached to poles will break that wind. Since the plants will still be smaller, a standard six-foot wide roll will be all you need. Leave about a foot between the screen and your plants, so that it does not freeze onto the plants. This simple method will give good protection from strong winds and keep your plants happy and healthy throughout the coldest weather. Do not wrap the plants completely, as they may become too warm inside, and start to grow too soon. Then, when you unwrap them, that new growth will be easily damaged by any late frost that may strike.

Don’t Let Snow Build Up

Whether this is the first winter for your plants, or they are well established, a heavy snow fall can cause damage, even to such a tough plant as Thuja Green Giant. Young plants can be pushed over by a heavy blizzard, and if not correctly trimmed, hedges can break open. With new plants, removing snow that may have pushed them over is best done when it is fresh and soft. Just push away the worst of it and make sure your plants are back upright.

With an established hedge, prevention comes from correct trimming. Keep the top of your hedge narrower than the base, both to keep the lower branches growing strongly, and to have less area on top where snow can build up. If you live in an area where heavy snow is normal in winter, a rounded top, rather than one cut flat, will shed snow more effectively. When you trim, run the trimmer down as well as up, so that the side branches are approximately horizontal, not growing upwards. Long, upward-facing branches can easily be pushed outwards, and break. If your side branches are horizontal, this can never happen and the heaviest falls will be shed by your sturdy hedge.

Next Fall

If you have problems with your hedge in winter, consider applying a special winterizing fertilizer in fall. These contain the right balance of nutrients to strengthen the foliage, and make it more resistant to cold and freezing conditions. Your hedge will be a rich dark green all winter, and come into spring ready to burst into rapid growth. These extra nutrients applied at the right time can really make a difference in an extreme winter.


Thuja Green Giant is a reliable and hardy plant across most of the country. If you live at the limits of its hardiness, these simple tips, that take just a little work to put into effect, will help you avoid any winter problems that may come along.