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Great Gardening by Sally Cunningham: Spreading the winter mulch

At last it’s time to spread the winter mulch, if you have some to spread. In an ideal end-of-season sequence, gardeners often gather mulch materials, stash the bags nearby, wait until the soil freezes, and then spread it over the dormant perennials or the woody plants’ root zones.

Unfortunately, neither professionals nor homeowners usually have the luxury of such timing: Either the warm weather persists, the ground doesn’t freeze, and the snow flies too soon, or there wasn’t time to find or buy the mulch. And the garden center may have put the bags away already.

What exactly is mulch? Mulch is material we spread on top of the soil. (It is different from compost – decomposed organic material that can be mixed into the soil or used on top.)

Organic mulch is material that came from living plants, such as shredded bark, wood chips, straw, cocoa shells, leaves, leaf-mold (composted leaves), or pine needles. In winter, snow is also a mulch.

Let’s consider your mulching choices even (or especially) in November.

If you have mulch standing by ...

You could wait to spread it until the ground actually freezes. (If you mulch sooner, sometimes rodents set up housekeeping under the mulch, near your plants.) But if this is your week to do it, just spread the mulch about 3 inches thick over the top of woody plants’ roots and around the perennials. (Cover the perennial crowns only after a deep freeze.)

If you don’t have any mulch yet ...

• Ask for shredded bark or other mulch at the garden center.

• Rake and gather leaves. If they are large leaves – oak, catalpa, horse chestnuts – chop them up with the lawnmower first. You can still pick up piles that neighbors pushed to the curb. Many trees have not yet dropped all their leaves.

• Watch for piles of needles, often White Pine needles, pushed to curbsides. (These are my favorites; I literally brake when I see pine needles, and carry garbage bags to collect them.)

• Pick up bales of straw, from a farm supply store, or leftovers from fall decorating projects. Do not use hay – way too many weed seeds.

• Cover large, weedy areas – or bare soil you want to save from weeds – with sheets of cardboard, thick sections of newspaper, tarps, or heavy black plastic.

Mulching, right and wrong

Mulching is not a requirement in gardens or landscapes. British friends often comment on the American obsession with mulching; we think a garden isn’t finished until the mulch is spread. An alternative, fine choice is to leave soil open, and manage weeds all season by raking, hoeing or pulling them.

Advantages to this method: The rain gets directly to the soil roots, and regular cultivating keeps the soil aerated.

In the landscape world, mulching beds with shredded bark or wood chips has become the norm. Most pros and customers consider landscape beds or mixed flower beds as unfinished until the mulch is spread. Mulch defines a planting bed and can be aesthetically pleasing.

Still, mulching can be done right or wrong, and the latter has bad consequences.

1. Say NO to volcanos. Just when I think everybody knows this, I see trees in a front yard or parking lot with mulch piled up the trunk. However this fad started, it was a terrible idea for tree survival. Cornell and other land-grant colleges called it “volcano mulching” and educators have tried to eradicate for at least 25 years. Don’t do it. Don’t let your landscaper or helper do it. Mulch should not touch tree trunks or the crowns of shrubs. Mulch against the tree trunk will produce rot and encourage insect and rodent damage.

2. Don’t keep piling and piling. Three or four inches of mulch is quite enough on top of woody plant roots, and probably too much around perennials during the growing season. The thicker the mulch, the more difficult it is for rainfall or watering to reach plant roots. For winter, thick mulch is a fine barrier, but check the depth in spring rather than automatically spreading more. If you are mulching for looks, consider removing some of the old, discolored material and putting a fine layer of attractive product on top. If you are mulching flower beds, do not crowd the plant crowns; leave a few inches around the plants.

Snow is good news
Some people cheer for it, and some roll their eyes, but from a plant perspective snow is a very good thing. Snow is a mulch. It keeps the ground frozen and prevents plants from heaving and thawing when the temperatures fluctuate. When it melts in spring it provides water to thirsty, awakening plant roots.

We should all wish for a constant blanket of snow, rather than periods of snowfall and then dry spells. Here’s hoping.

Here's more information about mulching:

Reasons to mulch:

Rather than routinely mulching your garden beds, consider why you are doing so. Understanding produces better choices. We mulch for these purposes:

• To block or smother weeds.

• To conserve soil moisture.

• To cool plant roots in summer heat.

• To insulate plant roots in winter and lessen extreme temperature changes.

• To reduce soil erosion.

• To prevent soil compaction.

• Because it looks pretty.

For a better vegetable bed:

Whether you have raised beds or flat beds, soil needs to be replenished for productivity and texture. Ideally, spread compost (any time of year, purchased or homemade) on the soil. Dump the finished potting soil from your container plants in there. Add some small or chopped leaves, straw etc. Then cover the whole space with cardboard, newspaper, tarps, old shower curtains or heavy black plastic. In spring you will be so happy to find enriched soil under the covers, and no weeds.

Sally Cunningham is a garden writer, lecturer and consultant.

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