Wintertime First Aid for Evergreens
After suffering through a harsh winter of heavy snows and sub-zero temperatures, evergreens sometimes need help.
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This young arborvitae has faded to a dull, dark bronze green (figure A), but the discoloration is perfectly normal, even though it causes many a gardener to panic. "In fact, I think it's one of the plant's attributes," says James, "because while I love its bright green color throughout much of the year, I also like the way it changes color in winter."
Discoloration occurs in other evergreens, as well, such as this arborvitae 'Sunkist' (figure B). While it stays gold throughout winter, the color becomes much more pronounced as temperatures warm.
Splayed or spreading branches are a common sight among evergreens, and they're typically the result of heavy snows that cling to the branches and weigh them down. Very often the only solution is to cut the branches back to a lateral branch or even the main trunk, but in the case of the false cypress, there's a much simpler solution: James wraps the splayed branches with a heavy twine. Giving a tug to force the branches into an upright position, James secures the branches in place with twine. "Once the weather warms up and the sap starts to flow more rapidly, the branches will remain upright and you can remove the twine."
This young pine, which also suffered from heavy snow, requires more help because the central leader is bent (figure C).
The solution is simple enough: drive a stake into the ground a few inches away from the base of the plant, and secure the central leader to the stake with twine (figure D). James checks the strength of the central leader every couple of months or so and, once it's able to stand up on its own, he removes the stake. "Along the way, however, I may remove some of the top growth just to lighten the load on the leader a bit."
The browning foliage on this fernspray Chamaecyparis doesn't look all that great, but it isn't anything to worry about (figure E). James planted this tree last spring and it had a tough time dealing with both intense summer heat and strong winds, which can cause leaf scorch. James rubs the branches to remove much of the dead foliage. For the pieces that cling to the branches, James gives a gentle tug. Be sure to wear thick protective gloves while handling the sometimes prickly foliage. "Believe me, this is much faster and easier than painstakingly cutting away all that foliage with pruners," says James.
However, James uses his pruners on this Leyland cypress that has a good deal of dieback, especially deep inside the plant (figure F). This kind of dieback can be caused by a number of different factors, including fungal disease, windburn or lack of adequate sunlight. In this case, a lack of sunlight in the plant's interior is the cause of the problem, which has also caused the condition known as "congestion," or the accumulation of dead branches in the plant's interior. The remedy in this case is to remove the dead branches.
"Where possible, I'll prune the dead growth back to a lateral branch, although in some cases, I may have no choice but to cut the branch all the way back to the main trunk," says James. Pick up all the pruning litter to discourage fungal growth.
Broadleaf evergreens can sometimes show dieback of branches due to windburn or winter drought, especially among rhododendrons, azaleas and boxwoods. If such occurs, a little corrective pruning will make them look as good as new.
Late winter to early spring is also a fine time to prune otherwise healthy evergreens either to control growth or enhance their appearance. The exceptions to this guideline are pines, which should not be pruned until new candles appear (figure G).
A light shearing on this Chamaecyparis will encourage bushier growth within the interior of the plant and help it maintain its natural shape (figure H). According to James, it's perfectly okay to trim branches that make the shape of the plant seem out of sorts. In such cases, however, James suggests trimming those branches all the way back to the main trunk.
And for those of you who like to fertilize your evergreens, keep in mind that nearly all evergreens prefer acidic soil conditions, so consider using a fertilizer made specifically for acid-loving plants, and apply it in early spring according to the package instructions.
"I should also mention that while I'm a huge fan of foliar feeding, evergreens are the exception because most foliar fertilizers--other than compost tea--can cause burning of evergreen leaves."
And speaking of acid soils, James is often asked about using pine needles as mulch for evergreens. "Well, actually I think they're great because they help maintain the proper soil pH and they look dynamite. Unfortunately, they're not readily available in my neck of the woods."
Finally, remember to water your evergreens regularly, even during the winter months since they never really go dormant.
An Alaskan gardener explains how to overwinter container plants.