Common Mulching Mistakes
Want a healthier yard? Stop the mulch madness! Use mulch wisely.
What's a drip line?
When it rains, water drips off the tips of the outermost limbs of trees. Imagine drawing around the tree right below those tips. That's the drip line. Most of a tree's small roots are located there rather than at the base of the trunk.
In order to grow, trees need oxygen as well as nutrients, water and light. What they don't need are suffocating piles of shredded bark at their base.
Mulch volcanoes deprive roots of air, prevent trees from getting the water they need, provide a haven for insects and pests, and encourage disease.
So why do people pile mulch around their trees year and year, creating mulch volcanoes? Perhaps they like the way a giant cone of mulch looks. Or maybe they see the volcanoes as a way to protect tree trunks from weed eater damage.
Whatever the reason, mulch volcanoes are a bad idea. A spread of one to three inches of mulch, however, is a great way to promote tree health.
Mulch should extend out to the tree's drip line. Not only will that protect the trunk from mower and trimmer damage, but it will also eliminate the tree's competition with turf for moisture and nutrients. And it will look good--far better than a mulch volcano surrounding a sick tree.
Best of all, a two to three-inch layer of mulch that extends to the drip line will help rather than hinder the tree's growth, well being and longevity.
Top 10 Reasons to Mulch
- Mulch helps soil retain moisture.
- Mulch suppresses weeds, especially when used in conjunction with landscaping fabric, black plastic sheeting or newspaper sheets.
- Mulch can be aesthetically pleasing, making flowerbeds, pathways, landscaping islands, sidewalk edges and other areas of the garden look neater.
- Mulch helps soil maintain an even temperature.
- Mulch helps protect plants from cold temperatures and ice damage in winter.
- Organic mulches like grass clippings, shredded leaves, pine needles and shredded bark add nutrients to the soil, improving it and increasing its ability to hold moisture and support germinating seeds.
- Mulch can slow down water run-off, diminishing the amount of fertilizer, dirt and debris that pollutes waterways.
- Mulch slows down erosion.
- Because mulch creates space between trees and turf, it reduces damage from weed eaters and lawnmowers.
- Organic mulch reduces soil compaction.
Depending upon their type, loose mulches should be applied in layers one to three inches thick.
Applying almost any mulch too thickly can result in the same problems that occur when plants are "volcanoed."
Lava rock, river rock, stones, gravel and sawdust (aged one year, minimum) should be applied in one-inch thick layers.
One to Two-Inch Layers
Spread compost and grass clippings in layers of one to two inches.
One to Three-Inch Layers
Wood chips (aged one year, minimum) are best applied in layers from one to three inches thick.
Two to Three-Inch Layers
Shredded leaves, pine needles and shredded bark work best if applied in layers two to three inches thick.
Old sawdust is excellent mulch for blueberries & other acid lovers.
The Wrong Mulch
TYPES OF MULCH
gravel, river rocks, lava rock
Are you using the right type of mulch?
All mulch isn't the same. Some works best for certain plants.
Like sawdust and wood chips, shredded bark is a poor choice for an herb garden and will cause plants to wilt. Neither should it be used in a vegetable garden.
Plastic mulch is a good choice for tomatoes & bell peppers.
Red, silver and/or black plastic mulch are among the best mulches for vegetables, as is a one-inch dressing of compost, particularly around heavy feeders like tomatoes.
Blueberry bushes, azaleas and other plants that grow best in acidic soil benefit from mulches like pine bark and pine needles.
Which Mulch is Best for Your Plants?
sawdust, compost, pine needles and/or bark
mushroom compost (has high pH)
organic matter and/or white gravel
sawdust or wood chips
Small fruits, such as strawberries & grapes
straw, sawdust, shredded leaves, grass clippings, newspaper, compost
Azaleas & rhododendrons
pine needles and/or bark
Tomatoes & peppers
red plastic, organic matter
wood chips, shredded bark
Mulch really is great. It protects plants, suppresses weeds, conserves moisture and more.
But that doesn't mean gardeners should use the same mulch (such as shredded bark) throughout their landscape.
The Best Time to Mulch
It's best to mulch when the ground is damp. Perennial herbaceous plants (plants that die down in winter & come back up in spring) should be mulched in late fall to protect them from the freezes & thaws of winter.
Not only should gardeners avoid using the same mulch throughout their landscape, but they should also consider leaving some soil either lightly mulched or completely free of mulch in order to provide a home for ground-nesting bees, which pollinate fruits, vegetables and flowers.
When spring arrives, mulch that was used to protect plants over the winter should be removed.
Mulch on Bulbs
Mulch on spring bulbs like daffodils, hyacinths, crocus and tulips should be brushed off in early spring after danger of freezing has past.
If mulch is left on bulbs, their new shoots may be pale or even colorless. They may also break.
Mulch on Perennials
Likewise, brush mulch away from perennial plants. Mulch that's piled heavily on their crowns could lead to rot.
If voles are a problem, avoid mulching the crowns entirely, especially on small fruits like blueberries and blackberries.
What type of mulch do you use?
Pest-free mulch that does not stink is the best kind to use. Mulch that has a chemical smell (such as sawdust and/or wood chips that have not been aged) should be avoided.
Also, mulch that's teeming with ants or other insects should not be used, particularly if it will be applied around foundation plants or other plants near homes.
About the Author
The Dirt Farmer has been an active gardener for over 30 years.
She first began gardening alongside her grandfather on her parents' farm.
Today, The Dirt Farmer gardens at home, volunteers at community gardens and continues to learn about gardening through the MD Master Gardener program.
© 2012 Jill Spencer