Advantages
Mulch has been called the gardener’s friend-and for a good reason. It offers three major benefits:
- Suppression of weeds
- Conservation of moisture in the soil
- Moderation of soil temperatures, keeping it warmer on cold nights and cooler on hot days
There are also many other benefits of mulch:
- In winter, protect plants from the cycle of freezing and thawing (which can heave them out of the ground)
- Prevent soil compaction and crusting
- Slow down runoff and erosion, especially on slopes
- Break down and feed the soil (if organic mulch such as clippings)
- Warm the soil in spring, allowing the gardener to plant days or weeks before the soil would normally be ready
- Keeping plants off the ground, especially tomatoes and melons, to avoid plant disease
- Keep plants clean, especially lettuce and celery, preventing rain from splashing soil that could carry disease into plants
Disadvantages
Although using mulch has many benefits, it can also be detrimental to the garden in mainly three ways:
- Over-mulching can bury and suffocate plants
- Mulch provides a convenient hiding place for pests
- Bake your plants with excess heat if done incorrectly
With most organic mulches, a 2 to 4-inch layer is plenty. The finer the material, the thinner the layer needed.
Unfortunately, mulch provides the perfect place for slugs, snails, and other pests to hide. Use shallow cups of beer to attract and drown them, or sprinkle wood ashes or diatomaceous earth around the base of precious plants to keep the slugs and snails at bay. Impervious mulches, like black plastic, don’t let air or water in. Even matted leaves can have that same effect, so shred or chop them up first.
Light-colored, wood-based mulches, like sawdust or fresh woodchips, can steal nitrogen from the soil as they break down. Counter this effect by adding a nitrogen-rich fertilizer, such as soybean meal, alfalfa, or cottonseed meal, to the mulch.
