New England gardeners have to expect some winter damage to plants no matter how well chosen, sited or cared for their plants may be. There are, however, several ways to keep winter stress and damage at a minimum.
The best insurance that plants will come out healthy the other side of winter is to make sure they’re well hydrated going into winter. Watering late into the year is especially important for broadleaf evergreens, needled evergreens, and new plants. October and November are statistically dry months. When the ground is frozen, from roughly December through March, plants do not “drink”. Unless you water, plants may go without significant water for SIX MONTHS!
Water until the ground freezes or at least past Thanksgiving. If the summer has been dry it’s especially important to provide extra water in the fall. Don’t over water. Plants require less water in the late fall than they do in the heat of high summer. The goal is to keep the root ball uniformly moist but not soggy. One inch of natural rainfall per week or an equivalent watering by you is usually sufficient.
See our Watering Guidelines, available in hard copy at the Garden Center, in the back of our catalog, or on our website.
Fertilizing after September 15th can encourage new growth that won’t have time to harden off before winter. Once the ground is nearly frozen in late November and December, however, you can apply fertilizers so that they will be available first thing in the spring. Note that organic fertilizers will not be effective until soils warm up in the spring.
Some aspects of clean-up in the fall are a matter of choice and some of necessity.
Thorough clean-up can prevent or at least reduce the intensity of disease and insect problems the following season. Here are just a few examples. Leaves that may carry the spores of fungi should be thoroughly removed from your property if at all possible. If your crabapples were infected with Cedar Apple Rust this year, this clean-up task is a priority. If your Asiatic Lilies fell prey to Red Lily Beetles, cleaning up all of the ripened foliage and stems is crucial to remove the favorite winter home of surviving beetles and eggs. Perennials within the Artemesia family should be cut back to prevent rodents from making nests beneath them.
Thorough clean-up can also prevent rodents from nesting for the winter at the bases of shrubs and perennials and using the plants as a convenient winter food source.
Selective clean-up can mean winter beauty. Ornamental grasses, Echinacea, or Sedum look lovely with a dusting snow. Think, too, about whether leaving some plant material will provide food for winter birds.
Because they don’t compact down like other leaves and allow air to enter and moisture to escape even when they’re wet, oak leaves and pine needles make terrific mulch. Don’t throw them away without considering their usefulness. Note that both can increase soil acidity.
Don’t forget to water your compost pile and turn it one last time before colder temperatures shut down biological activity. If you add chemicals that aid composting, do so before November. If your garden has had a serious fungus or insect problem, you may wish not to include infested plants in your compost pile.
Temporary mulch can go a long way to protect more tender plants over the winter by insulating roots against the late winter damage of the frost-heave cycle. The best mulches are pine needles, oak leaves, evergreen boughs, or bark mulch in a pinch. Research your plant first – for example, some perennials resent having their crowns covered with anything that retains too much moisture. Don’t put down protective mulch too early. You may be making a perfect winter nesting site for rodents that view the protected plant as a convenient food source. Instead, wait until the ground freezes or is about to freeze, usually no earlier than late November. Protective mulches must be removed in the spring when the soil warms up, usually no later than April 1.
An application of an anti-desiccant spray at the end of November will help protect evergreens – especially newly planted ones — from the drying winds and harsh sun of winter. The goal is to spray the top of the foliage, not the underside, and the temperature must be above freezing. Some people are trying sprays on woody stems of hydrangeas and roses to reduce winter damage. Wilt-Pruf is one of several branded products.
Dry cold winds, bright reflected sun, and road salt can damage foliage very quickly during the winter. Plants on berms, hillsides, rooftops, at streetside, or in other exposed locations should be protected. Burlap, screening, waxed cardboard, Styrofoam, and plywood are all used to make barriers. The barrier should be sized so that, if possible, it is not touching the plant, staying about 4” away. It should be sturdy enough to carry a snow load without collapsing against the plant. All winter wraps should allow some moisture and air to enter around the plant.
Tree wraps are a good idea if you’ve had trouble with rodents girdling plants, with deer browsing or rubbing their antlers on trunks, or if you’ve recently planted a young thin-barked tree (such as a sugar maple, cherry, apple, or pear) that sunscalds easily or may be vulnerable to frost cracks. Wrap from ground level all the way up to the branches. Apply as late as possible in the fall and check as early as possible in the spring. Never leave tree wraps on without periodically checking the bark beneath and loosening the wrap when necessary.
Plan in advance to prevent damage from snow storage or removal. Burlap or wood structures offer good protection. Reflective markers on stakes provide warning to plows for where (or where not) to plow or pile snow. If you must pile snow on plants, do so carefully to encase rather than flatten the plant.
Heavy snowfalls can weight plants down to the breaking point. If the snow is still loose, you can brush it off gently with your hands or a broom. If it is at all frozen to the plant, leave it alone. You’ll do more harm than good. Even a deeply bowed plant can right itself during the next spring, perhaps with a little judicious staking if necessary.
Some de-icing products are okay near plants, and some are not. Urea and potassium chloride products are generally safe. Read the label. If your plants are near a major roadway or any area that is sanded and salted, you might consider putting up a burlap barrier that will deflect the majority of the sand and salt. This can also help to protect the edge of a lawn that suffers from sand and salt. In the spring, rake off as much road sand as possible and be sure to water the area thoroughly both to dilute the salt as much as possible and flush the rest as deeply into the soil as possible, hopefully below root level.
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All remnants of plants should be removed to prevent future disease problems. Many vegetable gardeners prefer to accompany fall clean-up with tilling and fertilizing the soil. Aged cow manure or compost can be layered over the beds and be allowed to rest over the winter or turned in right away. An application of organic slow-release fertilizer and/or lime after the soil is cold will be ready for plants to use right away in the spring when the soil warms up to about 40 degrees F.
Sowing a green manure crop, such as winter rye, that can be tilled in when spring arrives is a terrific way to replenish organic content of garden soils.
If you have cold weather crops such as potatoes, carrots, turnips, or brussels sprouts they, of course, can stay in the ground until harvested.
DECORATIVE CONTAINERS, ETC.
Containers that remain outside with plants, just soil, or just plain water in them can be cracked by the expansion of freezing water. If possible, bring them inside to a garage or covered porch. Containers and statuary made of ceramics (either glazed or unglazed), cast stone, some fiberglasses, and even some cements should be at least emptied and turned upside down. If the container is too large to move or invert, secure a heavy-weight plastic bag over it with strong tape or cord. Even a piece of plywood laid on top will help.
As with its container the best course of action is to bring the plant into a garage or covered porch or other freeze-proof place for the winter. Water only to keep the soil moist. If the container and plant must stay outside, make sure you water until the soil in the container freezes. Use an anti-desiccant spray on evergreens, and install a windbreak if the plant is exposed to harsh sun or wind. For example, you have a Dwarf Alberta Spruce in a cement planter.
Spray with an anti-desiccant. Water until the soil freezes. Wrap the plant with burlap. Wait for spring.
Don’t forget that fountain pumps should be taken in for the winter. The fountain basin and any part that retains water should be emptied. Cover to exclude water.
TOOLS AND CHEMICALS
Take the opportunity during the winter to repair, sharpen, and oil your tools so they’ll be ready to use in the spring. Don’t forget lawnmower and power tool maintenance and winterizing. Make sure any liquid chemicals are stored where they won’t freeze. Granular and powdered products need only be kept dry. Double check your inventory to make sure you’ll have whatever pesticides you might need in late winter when they may be more difficult to purchase (a good example — dormant oil).
Start early with deterrents so that deer are encouraged to change their habits from last year as soon as possible.
Repellants can be effective when population pressure is moderate. The many products on the market – bad tasting sprays and predator scents – should be applied early and reapplied as necessary throughout the winter. Use more than one brand and alternate so that deer don’t become comfortable with any one scent.
Temporary fences are the most effective when they create at least the illusion that they can’t be jumped. Fencing should be a minimum of 6 feet high, preferably 7 or 8. It should be located so that it is far enough away from the plant not to allow deer to push against it and eat through it but not so far away (no more than 4 feet) that they feel comfortable jumping between it and the plant. A double fence line (two fences 6 feet apart) is even more effective.
A particularly choice plant can be individually protected with burlap.