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By Kathy LaLiberte
Though October always finds my gardens looking tired and disheveled, I still treasure every bit of remaining color and interesting foliage. But by November, I'll have said my last goodbyes. The gardens will be thoroughly blackened by frost and it will be time to get busy again, putting things to bed.
I have come to love this last chore of the season. The weather is cool, the light is beautiful, and there's no need to rush about. Another great thing about putting the garden to bed is that even if you accomplish nothing at all in the way of cleanup and mulching, your garden will probably be just fine. But if you do have a few hours to spare, here are a couple fall tasks I find beneficial:
Why cleanup?: Removing spent plant material from your gardens reduces the amount of disease spores and insect eggs that could cause problems next season. It also neatens up the garden so you're not looking at a disheartening tangle of dead foliage all winter. Your spring "to-do" list will be a little shorter, too! If your time is limited, just get after the messiest plants and don't worry about the rest.
Once you've had a hard frost, pull out and compost any annuals (if they're diseased, keep them out of your compost pile). Most perennials can be back to 3 to 4 inches high. Leaving some stubble will help you locate the plants next spring, and also helps insulate the plants from extreme cold by holding mulch and snow over the crown of the plant.
Some perennials, including ornamental grasses, Autumn Joy sedum, achillea (yarrow) and stachys (lamb's ear), look good even after frost and add garden interest right through the holidays. You may want to leave these in place and just cut them back next spring.
Why mulch?: The biggest benefit of winter mulch is that it helps to moderate soil temperatures. Rather than thawing and then re-freezing every time there's a sunny winter day, soil that's covered with a layer of mulch will usually stay a relatively consistent temperature. This helps keep your plants fully dormant until spring arrives, and also minimizes damage to the roots that can be caused by frost heaving.
If you have dependable snow cover from December through March, you probably don't need to mulch. But these days, even in the coldest parts of the country, that's rarely the case.
Which plants should be mulched? I'll admit that I mulch selectively, focusing on my garlic and a couple tender favorites that I know may not survive a zone 4 winter. The amount of mulching you do in your own garden depends on the severity of your climate, the condition of your soil, the kinds of plants you have, the amount of mulch materials you have on hand, and how much time you can devote to the task. Remember that in most cases, winter mulching (like cutting back your perennials) is one of those good but not essential tasks. If you can't mulch everything, concentrate on plants that may be marginally hardy or those that you especially treasure.
When to mulch: If you do mulch, don't rush it. Plants should enter winter dormancy slowly and completely. For this reason, mulches should be applied only after the ground has frozen, which in many areas will be around Thanksgiving or the first week of December. Once the ground begins to thaw next spring, it's important to pull the mulch several inches from the crowns of your plants. This will give newly emerging growth access to sun and good air circulation.
What to use for mulch: An effective winter mulch must be water- and air-permeable so as not to smother the plant below. Non-matting winter mulch materials include: shredded leaves, evergreen boughs, pine needles, salt hay, weed-free straw, chopped cornstalks, wood shavings and compost. Do not use whole leaves; they pack down and can suffocate the plant they're intended to protect. For most plants, 4 to 6 inches of mulch is adequate. Roses should have a full 10 to 12 inches of soil or compost mounded up over the crown of the plant.
In exposed areas, you can use garden fabric or burlap to hold organic mulches in place. Many professional growers cover container-grown plants and beds of young perennials with an extra-thick garden fabric, such as GardenQuilt. In my own garden, I lay GardenQuilt over a 3-inch layer of straw to insulate my fall-planted garlic bed.
Once nighttime temperatures begin dropping into the 20s, I will often spread a 6- to 10-inch layer of straw over my carrots and beets. This protects the quality of the vegetables, and keeps the soil from freezing so I can continue harvesting into December.
Moisture is important: Most winter plant damage is actually due to moisture problems, not cold temperatures. In dry climates, such as Colorado, as much as 95 percent of the winter plant loss is due to dehydration. In wet climates, such as the northeast and the Pacific northwest, both soil and plants can get waterlogged during the winter and either suffocate or be damaged by frost heaving.
All plants should enter winter dormancy well hydrated. If you garden in a dry climate, or your area is suffering from drought, continue watering your plants regularly until the ground has frozen. If your climate is very dry, your plants may need monthly watering right through the winter (even if the ground is partially frozen).
Plants in wet climates face the opposite problem. You can't stop the rain, so the only solution is to facilitate good drainage. Add organic matter to the soil, plant in raised beds, and be careful about where you site your garden and your plants. I've found that certain plants are more intolerant of wet soil than others. Russian sage (Perovskia) hates my heavy soil and though it is supposed to be hardy in my zone, I have yet to get a plant through the winter. In general, plants that are native to dry climates (such as the Mediterranean or the mountains of Central Asia) can be mulched, but they may not survive the winter with wet feet.
Wind protection makes a difference: Cold, drying wind is another major hazard for plants. If your garden is in an exposed area and/or you get lots of dry winter wind, your plants will really appreciate some wind protection as well as a layer of mulch. Shrubs, hedges, fences and walls can buffer the wind and help maintain a protective soil covering of mulch or snow. You can also protect plants from wind damage with a temporary windbreak made from shade netting or burlap.
So prune things back and cover up what you can, but leave yourself plenty of time for apple picking, leaf peeping and the other delights of autumn.
Last updated: 7/9/19
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