To mulch... or not to mulch? That is the question. And if you do mulch, what should you use? There are several mulches that work well for winterizing your plants. Straw, hay and leaves are the most commonly used materials. Each has its strengths and weaknesses.

Straw
Straw is the stems of plants (usually wheat or oats) that have been baled after the seed heads have been harvested. It makes a good mulch because it is lightweight, does not compact readily, provides good insulation and has very few seeds. The drawbacks are that it can shift with the wind and is extremely slow to break down, even in a compost pile. Straw is a light, golden yellow color. A dry bale should weigh between 25 and 40 pounds, depending on how tightly it was baled. Shaken out for mulching plants for the winter, a bale will cover 35-50 square feet 4-6 inches deep. Straw is also commonly used in doghouses as winter bedding. For plants, straw has little or no nutritional value unless it has been thoroughly composted.

Hay
Hay is actually whole plants, leaves, stems and all. It has been cut, allowed to dry and baled. Ideally, hay is harvested just as the flowers or seed heads mature. Hay makes a good mulch because it stays in place, provides insulation and will degrade in less than a season. The drawbacks of using hay are that it can have quite a few weed seeds and it tends to mat down. Hay is a dull grey-green color and includes the stems, leaves and flower/seed heads of the plants. An average bale of hay will be heavier than straw, usually between 35 and 60 pounds, depending on how tightly it was baled and the moisture content. A bale of hay shaken out for mulching plants will cover approximately 35-50 square feet 4-6 inches deep. Like straw, hay doesn't have much nutritional value for your plants unless it has been composted. Many gardening books recommend salt marsh (or just marsh) hay. Salt marsh hay would be wonderful if it were available locally, but since Minnesota isn't known for its saltwater marshes, we can't get it. The type of hay Bachman's usually offers is annual Canary grass (Phalaris canariensis).

Leaves
Many of us are fortunate enough to have leaves for fall mulching. The leaves from most deciduous trees do a good job and the price is right. Larger leaves tend to mat and will work better if they have been shredded. If you don't have a leaf shredder, try running them over several times with your mulching lawn mower. Avoid using black walnut leaves. Shredded leaves work well as a summer mulch, too. They can be left in the garden to decompose if you pull them away from the crowns of the plants.

Quality hay or straw will be dry and not have any unpleasant odor. A wet bale, whether it is hay or straw, can be incredibly heavy and almost unmovable and can be full of mold spores. While this isn't dangerous for the plants, it is difficult to work with and breathing the molds can be dangerous to people and animals.