We mulch in warmer months for weed suppression, moisture retention, and to keep the ground warm. In winter months, mulch is also used to retain water, however, winter mulch keeps soil insulated to remain cold so plants can stay dormant.

Holy moly, did the cold weather come in fast. Fall is usually the time when I am leisurely puttering around my garden, cutting down spent perennials and otherwise slowly tucking my beds in for a long winter’s nap. Now that we have had our first hard freeze, I am rushing to get my mulch down.

We mulch in warmer months for weed suppression, moisture retention, and to keep the ground warm. In winter months, mulch is also used to retain water, however, winter mulch keeps soil insulated to remain cold so plants can stay dormant. Those few warm days that get thrown our way in the middle of a bunch of cold ones can have plants thinking it is time to grow. The imminent cold that will return will kill tender growth produced during that time.

Winter mulching also prevents heaving. When the ground freezes and thaws, the soil contracts and expands. This will cause plant roots to be pushed up from the ground, exposing the crown and roots and making them susceptible to frigid air and drying winds.

Here are a few mulch options and their pros and cons:

Pine straw and bark

Pine needle mulch (pine straw) is widely used for a variety of reasons. It is one of the least expensive options on the market, and if you are fortunate enough to have pine trees on your property, it’s a great free option.

Pine bark mulch breaks down fairly quickly, which is great because it adds nutrients to the soil. The downside to that is you will need to replace it regularly. It also has the potential to draw bugs, especially spider mites. It is not very good on slopes or areas where rain water can easily wash the mulch away.

Straw and hay

Straw and hay are not considered as aesthetically pleasing as other mulches, but they provide excellent insulation in both summer and winter. Straw, in particular, is a favorite choice for winter mulching because the straw needles are hollow, providing dead air space, which is ultimately the perfect insulator. They are also the mulch of choice when seeding a new lawn.

Hay, unfortunately, has the con of often being riddled with weed seeds, thus introducing weeds into the garden that weren’t there before. Unless available free of charge, it is a slightly higher priced option than pine needles or bark.

Leaves

Leaves are a wonderful free mulch. However, they need to be shredded before use. They are very good when used over vegetable beds in the fall, as they will decompose through the winter.

They are commonly used around trees and bushes in less formal settings. The leaves also attract earthworms, which are beneficial to garden soil health. They help with soil aeration and compaction as well as nematode control.

Leaves over time have the tendency to compact together and form a mat, which will inhibit air and water flow, especially if not shredded.

Grass clippings

Grass clippings are high in water content so they decompose very quickly. This, unfortunately, makes them very slimy and gives off a bad odor. If clippings have been treated with herbicides, pesticides or weed killer, they can be harmful to your plants. Grass clippings are best left on the lawn to return nutrients to the soil.

Rocks and gravel

There are a variety of inorganic mulches available as well. Rocks and gravel, although they create a very clean look, can be expensive. They also absorb heat from the sun, which can cause the area to become hot and dry. Rock and gravel mulch are also used in conjunction with plastic or fabric sheeting, adding to the cost. Plastic sheeting does not allow proper air flow or allow for water to penetrate through to the soil. Although fabric allows for water and air to pass through, weeds can also penetrate the fabric.

Rubber

Rubber mulch is usually made from ground, recycled tires and dyed to compliment or stand out in the garden. It is good at suppressing weeds and for maintaining moisture in the soil. There are still studies being performed to determine the toxicity of rubber mulches. It does not break down and can remain in the soil for long periods of time. It is one of the more expensive mulches.

With any mulch, make sure to keep it at least a few inches from the base of plants and trees. Mulching should be done so it is at least a few inches thick. Some tender perennials and young trees may also need additional wrapping with burlap or sheets to protect them from winter cold and winds.

Mulching any time of year is a good idea, but it is especially important to protect your sleeping beauties in winter. Until next week, happy gardening.

— Irland, a member of the Limestone County Master Gardeners Association, can be reached at kippirland@hotmail.com. Visit http://mg.aces.edu/limestone for more information on the Limestone County Master Gardeners.