Winter Mulches for Vegetable Gardens

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Pine needle mulch for strawberries over winter

Just like you, I put a lot of time and effort into creating deep, fertile soil for my homegrown vegetables. As fall turns to winter, my efforts focus on holding onto what I have, which means covering all exposed soil with mulch for the winter. Organic mulches cushion the soil from compaction and erosion caused by heavy winter rains while safeguarding the soil’s storehouse of nutrients. In addition, winter mulches can enhance the cold tolerance of perennial vegetables, herbs and fruits, helping to insure a strong comeback in spring.

In autumn, the most widely available organic mulches include leaves, compost, pine needles, wood chips, sawdust, and evergreen boughs. Which mulch should you use where? One of the advantages of using the GrowVeg Garden Planner is that you can decide now where you will plant your main crops next year, and tailor your winter mulching to suit the needs of the bed’s future residents. For example:

  • Vine crops like squash and pumpkins can be sown or transplanted into a plot prepared the previous fall and mulched through winter with leaves. Because you want the leaves to persist into the next growing season, there is no need to shred them, though coarse chopping with a mower helps keep leaves from blowing about. Research has shown that leaf mulch leads to bigger, better pumpkins, with radically reduced problems with weeds.
  • Tomatoes and wood chip mulch doesn’t sound like a likely partnership, but as more gardeners are using wood chip mulch (which often can be obtained free from tree trimming crews), reports keep coming in on the glories of wood chip-covered garden beds. When allowed to decay at the surface, the chips host a huge range of fungi, which enrich the soil along with the decomposed wood chips. Best of all, a perpetual wood chip mulch provides poor habitat for slugs and small rodents compared to most other materials.
  • Strawberries thrive when given a moderate mulch of pine needles or straw in late fall, after they have stopped growing, with more mulch added in spring. Sawdust also makes a fine winter mulch for strawberries, as well as blueberries, raspberries and other small fruits.

Multi-Layered Mulches

Beds where I plan to grow broccoli, spinach and other heavy feeders get the best winter mulch of all – four or five layers of whatever organic materials I have on hand – leaves, rotted sawdust, garden waste, etc., -- stacked and dampened until it’s about 6 inch (15 cm) deep. Then I cover the moistened mulch with a piece of burlap or old garden blanket to create comforter compost – a quilt of biodegradable materials that can be turned under or raked aside in spring.

Covered mulch
Layers of mulch covered to prevent wind blowing them away

The folks at the Interbay P Patch Community Garden in Seattle, Washington, take such layered winter mulches even higher with Interbay mulch, wherein beds are stacked with mulch up to 18 inches (35 cm) deep, and then topped with burlap coffee bags. Covers that block light are a special aid to decomposition because they provide good conditions for microorganisms that need darkness to thrive.

Structured Protection

Gardeners who grow perennial flowers are familiar with the practice of placing boughs cut from junipers and other evergreens over dormant plants, which protects the crowns from ice and harsh winter winds. I find evergreen boughs equally effective when placed over marginally hardy herbs like rosemary and parsley. Evergreen boughs also can help nurse hardy veggies like spinach through winter, because they shelter the plants while still admitting filtered light.

In home vegetable gardens, tunnels covered with row cover, plastic, or cloth (such as thrift store window coverings) keep soil safe through winter, just like mulches. Tunnels generally keep soil warm and dry compared to surrounding soil, too. While not exactly mulches, tunnels made from cloth or row cover attached to wire arches are a winter treatment worth considering for beds you plan to use for your earliest spring plantings.

Tunnel in the snow
Tunnels can provide good protection from snow

Especially in small gardens, don’t forget that pulled plants, piled on the garden’s surface, can be the easiest way to mulch some beds in winter. Until you move the debris piles to a larger compost heap in early spring, each little mound of decomposing material will serve as an oasis for earthworms and other soil-building critters. Little piles of garden garbage also make great habitats for field crickets, which have huge appetites for weed seeds.

Last year we had an unusually snowy winter, and snow can double the beneficial effects of any mulch by maintaining steady temperatures at the surface. But snow cover is always an iffy proposition compared to winter mulching - the most dependable way to safeguard precious garden soil between now and spring.

By Barbara Pleasant

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Comments

 
"We have so many (free and sustainable) sources of mulch here in the SE United States. Thanks for the tips on how best to utilize them...The article was a lovely read:)"
Kristen on Monday 1 November 2010
"yes. the options for covering one's are as bountiful as the crops you experience when you do so,"
agaja on Monday 1 November 2010
"can I use fresh bark and sawdust - I've heard that may be too strong and potentially lethal or should they be left for a month or two before applying? "
di green on Thursday 4 November 2010
"The danger is in the dosage when it comes to compounds that leach from wood, but not much harm can be done this time of year since few plants are actively growing. If your soil already has a good appetite for woody things (meaning lots of fungi are present) go ahead and use your mulch materials in fresh form. Otherwise, set them aside and let them get rained on a few times first. You will love what they do for your soil."
Barbara Pleasant on Thursday 4 November 2010
"I too was surprised by this advice to put fresh wood chips on a garden. I was under the impression that they were quite acidic and had to be composted before using as mulch. "
Monica Reinagel on Friday 5 November 2010
"I covered my whole veggie bed this fall just before the first rains started and it's been about 3 weeks now. We've had some really warm days since and my whole garden is full of sprouted seeds from the straw. I guess I didn't get it on thick enough. Any thoughts?"
Brenda on Sunday 7 November 2010
"Brenda, my suggestion would be to use a sharp hoe to quickly slice through the stems of the sprouted seeds under the mulch. You may then have to add more mulch on top but the sprouted seeds will just act like a green manure (cover crop) and rot down to benefit the soil. If the warm weather continues you may need to repeat this hoeing."
Jeremy Dore on Wednesday 10 November 2010
"Monica, the rules are changing, and wood chips are turning out to be a darn fine mulch. They decompose so slowly that the soil pH has plenty of time to adjust itself, and the fungi that live ON and IN the wood chips make wood chip mulch worth more than "the sum of its parts." Brenda, as long as the seedlings are growing, they are accumulating organic matter. If they're not killed by winter cold, you can pull them and compost them in spring. "
Barbara Pleasant on Wednesday 10 November 2010
"Barbara, would this also apply to the shredded hardwood mulch that you buy at garden centers? Also, perhaps you could address this in a different post: A couple of times a year (spring and fall) I turn over my entire garden to the depth of about a spade and chop it up--to kill weeds (or turn under winter cover crops) and loosen up the soil. But I was reading something on an extension service website that it's best to do as little cultivating as possible so not to disturb the top layer of soil. The turning and chopping takes a lot of effort. Should I stop?"
Monica Reinagel on Wednesday 10 November 2010
"Thanks Jeremy. What you suggested is doable. I tasted a sprout and couldn't believe how sweet it is! It's on the tough side for putting in salad though. Hmmm, maybe I'll try steaming a handful and see if that makes it edible."
Brenda on Wednesday 10 November 2010
"Monica, you are right. There are times to cultivate, like just before planting, and times to leave the soil's life forms undisturbed. I'll take your tip, do some research, and find good answers for when and when not to cultivate. Personally, I cultivate less in the fall than I used to, and rely on mulches and cover crops to recondition the soil. I do address areas where I've had insect or disease problems by cleaning them up and digging in compost."
Barbara Pleasant on Wednesday 10 November 2010
"thanks for all the advice really helpful. Can I ask another what are your views on the best use of wood ash? "
di green on Thursday 11 November 2010
"Di, we have a wood stove, and each time we empty the ashes I sprinkle them very lightly over all of my cultivated beds and beneath our fruit trees. As long as the ashes are applied very lightly, they add nutrients and don't upset the soil pH or earthworms. We keep extra in a small metal garbage can for use in spring and summer."
Barbara Pleasant on Thursday 11 November 2010
"We have used wood ash on our veggie bed as well. We use more than Barbara and have not had any problems. Our garden is located in Northern CA. The earthworms thrive-one thing that I also do is dig holes in random places in the garden and put in veggie trimmings from the kitchen then cover them with dirt. I think the worms like this :)"
Brenda on Thursday 11 November 2010
"thanks- that's good to know"
di green on Friday 12 November 2010
"We mulch with seaweed! We live near the ocean and after a rough storm, we go to the beach with old trash barrels, fill them up with dead seaweed from above the tide line. We bring them home and allow then to get rained on a few times (to reduce the salt) them use it to mulch all of our raised beds and perennial beds. Every year my neighbors are amazed by my "No Miraclegro" awesome garden."
Gail on Wednesday 28 September 2011
"Could 'moldy' straw be used as a winter mulch for vegetable garden. Also I'm reading of folks using wood chips for this purpose, but am curious about this raising the carbon/nitrogen ration in the soil, which I always understood shouldn't be done. Finally if 'seasoned' hardwood chips are ok, would chips from a bois d'arc tree be ok to use. "
Steve on Wednesday 4 January 2012
"Moldy straw is great, but wear a breathing mask when handling it as fungal spores present can cause what was once called "farmer's lung". Any wood chips other than walnut are fine as mulch. After weathering on the surface for a season, you can turn them under."
Barbara Pleasant on Thursday 5 January 2012
"Thanks: good point about the breathing mask, but am still curious about raising the carbon/nitrogen ratio with wood chip mulch and tying up the soil microbes. Is it that this is not a problem in the winter since their are no plants growing."
Steve on Thursday 5 January 2012
"I've had good experience using woodchips. The seeds germinating in "straw" sounds like the gardener actually had hay. Hay is grown to feed animals and is rich in nutritious seeds; straw is nearly seed free - just the stems after the oats are harvested. There's a big difference which I learned the hard way. With hay you get a weed garden, with straw that clean mulch look and function. Most people use the terms interchangeably, but for mulching purposes there's a big practical difference. As far as I'm concerned there's no such thing as mulch hay- it's a contradiction."
erika on Monday 25 June 2012
"can you use newspaper as mulch?"
maria buniva on Saturday 13 October 2012
"Yes, newspaper makes a good base layer for a mulch sandwich. It blocks light to weeds, so enhances weed deterrence for whatever material is on top of it. You do need to cover it with something else, like shredded leaves or straw. "
Barbara Pleasant on Sunday 14 October 2012
"Hi there could you use newspaper and then cover it with landscaping fabric for the winter? thanks! "
Christa on Sunday 21 October 2012
"Hi! What is the minimal thickness of mulch tho be effective? And should I turn the soil in spring mixing it with mulch? Thanks"
Bulasty on Thursday 12 December 2013
"Newspaper can go beneath any type of biodegradable mulch. It is great to use as an "undermulch" in summer because it suppresses weeds better than loose mulch...Bulasty, three to four inches is the target depth year round, and you can go deeper in winter. In spring, rake off unrotted material from the top and turn under the rest when preparing beds for planting."
Barbara Pleasant on Saturday 14 December 2013
"Your comments on wood ash were interesting. I too have a ready supply and for a couple of years I have been using this to create a barrier between the lawn and the borders. I apply initially a barrier about six inches wide and three to four inches deep. This quickly consolidates and becomes stone colored. So far no weeds have penetrated this barrier and mowing the lawn has become less of a chore."
George on Sunday 15 January 2017

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