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Gardener’s Guide to Mulch
Why bother mulching your yard, garden or commercial property? Protecting the soil with mulch, also known as ground cover, is one of the most beneficial things you can do for your ornamental or garden plants and trees. Mulch guards against erosion, helps plants maintain their equilibrium during weather variations, and holds moisture in. Mulch cools the soil temperature during the growing season and protects perennials, shrubs and trees during the winter months. Mulch also helps stop weed growth and, if you choose organic options, improves the soil. Plus, it just looks nice.
Done correctly, mulching can optimize plants’ cultivation to suit changing conditions. Nutrient uptake is faster with warmer soil and slower with cooler soil, while a plant’s gestation may require cooler soil. In Michigan’s variable climate, you may need to warm, cool, both warm and cool, or neither, the soil in the course of a growing season.
Organic Mulch vs. Inorganic Mulch: There are two basic categories of mulch, organic and inorganic. Both act as ground cover and offer the benefits of insulating and retaining soil. Within each category, the types of mulch vary widely in appearance and longevity. Organic mulches also augment the soil by disintegrating over a year or two, so they need to be reapplied. Inorganic mulches are more permanent, but, because they don’t break down, they do not improve the soil structure. Before you add mulch to your garden, you’ll want to take a few minutes to learn about how much you should apply, both for the benefit of your plants and to prevent yourself from buying too much or too little material.
Organic Mulch: Organic mulch fertilizes sandy soil and helps hold water and nutrients. It also slows the warming of the soil. This may be the most cost-effective option because you have the beginnings of organic mulch right in your own backyard or recycling bin: grass, leaves, and newspaper are all excellent mulch for vegetable gardens, as they keeps weed growth down and protects low-hanging vegetables.
Organic mulch options are best for trees. Whichever type you use, layer it right up to plants but leave gap of about 2″ around tree trunks. If possible, mulch at least to the tree’s drip line, and further out if it’s practical, to nourish the tree’s roots.
Wood Mulch: Shredded hardwood mulch works well at keeping down weed growth and does not wash away easily. Shredded hardwood lasts longer than other wood mulch and is very attractive. Various particle sizes are available, from shredded bits to chips and nuggets.100% Cedar Mulch has a beautiful scent that will discourage pests without the use of toxic herbicides. Double Shredded Hardwood Mulch is the easiest to use, as the pieces are uniformly smaller. The finer the pieces, the easier they are to distribute in smaller areas or around compact plants.
Color enhanced mulch is hardwood mulch, colored red, black or brown with lightfast, water-based dyes that are safe for plants, pets, and people. It retains its color much longer than other hardwood mulches.
Pine bark is usually dark in color and lends an attractive, woodsy look to your garden areas. It can last up to three years before needing replacement.There are two drawbacks with pine bark, however: It can float away after a hard rain, and it can provide a home for carpenter ants, termites, spiders, millipedes and beetles, who may decide to expand their territory your home or other buildings.
Pine needles are best for shrubs, trees and plants that love acid environments, such as azaleas, camellias and rhododendrons. This type of mulch is better for drainage than wood mulch, and looks great. However, pine needles are scarce or non-existent in some areas.
Grass clippings can be used as mulch as long as the lawn they’re from hasn’t been treated with herbicide. Spread the clippings in a 2″ to 3″ layer. The clippings will decompose quickly and will need to be topped up regularly.
Leaves are another readily available organic material. Before application, they must be chopped up with a lawnmower or shredder. Then distribute the shredded leaves 3″ or 4″ deep if wet, or 6″ thick if dry. The leaves will decompose quickly and will need to be topped up regularly.
Manure will work well for a backyard or vegetable garden, though probably not in a front yard or a commercial property. Put down a 3″ to 4″ layer of manure and then rake into the soil before planting.
Newspaper with black ink only makes a good mulch; pull out the pages that have colored ink as they can harm your plants. Use 3 or 4 sheets per layer and anchor them with another 2″-3″ thick layer of soil, leaves, grass clippings or a combination.
Inorganic Mulch: This category includes stone, landscape fabric and plastic. Though these materials are not as beneficial to the soil as organic mulch, they last much longer. Inorganic mulch promotes warming of the soil. Black plastic does not work well in landscaping but may be useful in a vegetable garden, especially if drainage isn’t a concern, because it retains water. Landscape fabric is applied to the surface of soil before planting and is porous so it allows water in but keeps weeds out. Stone is used on paths, around walkways and around permanent plantings, such as shrubs and trees. Stone does not work well for vegetable or flower gardens.
Plastic sheeting: Black polyethylene plastic is effective at preventing weed growth, and keeps the soil warmer, making it a better choice for vegetable gardening than landscaping. Keep in mind that along with holding heat in the soil, it tends to hold water as well. If your property or garden bed doesn’t drain as well as others, you may want get black plastic with tiny holes pre-punched in it.This type will still retain more water than organic types of mulch.
Exposed to sun, black plastic can degrade and lose it effectiveness, which is why some gardeners bury it in the soil. White plastic will cool the soil by reflecting the sun’s rays and will also prevent weeds. Both plastic acts as a good underlayment for organic or rock mulches. If you are using black plastic for a vegetable garden, lay it down two weeks before you plant anything so that it will heat the soil. Then cut holes in the plastic when it’s time to plant.
1. Smooth the soil with a rake. The more level it is, the better.
2. Wet the soil lightly. Plastic won’t stay put if the surface is dry.
3. Place the plastic onto the planting bed.
4. If you are not going to put either wood or rock mulch over the plastic, make sure the plastic is in close contact with the soil. This will allow for maximum heat transfer.
5. Use soil or rocks to hold down the edges.
Decorative Stone: Decorative stone works best with plants that thrive in an alkaline environment, such as boxwood, euonymus, forsythia, lilacs, and clematis. It is one of the best draining mulch types. Stones used for mulch are usually smaller and are well-suited for foundation plants (trees and shrubs that are basically permanent). There are several types of stone that work well for mulch, including brick chips, crushed gravel, pea gravel, pebbles, crushed stone, white marble chips, and river rock. All types will control weeds for at least a few years and won’t need replacement unless the layers settle. Areas of decorative stone are basically permanent, so consider carefully where you want to put them. They need to be edged, with the edging material going approximately 3″ into the soil.
1. First mark off the area you intend to fill, remove any grass or other vegetation if necessary, and then line with edging material to form a sharply delineated border at least 3″ deep.
2. Pull out any weeds or other plants, large rocks, and anything else that disrupts the surface.
3. Smooth the soil with a rake.
4. Make the area inhospitable to weeds: Apply an herbicide to it and cover with landscape fabric.
5. Distribute your choice of decorative stone evenly.
Landscape Fabric: Landscape fabric is sold in a range of widths and lengths and is specially treated to resist rotting. Landscape fabric works best for shrubs and non-spreading plants.It will stifle spreading plants. Unlike plastic, landscape fabric is porous and allows water, air and nutrients to pass through. It will also sometimes allow weeds but better weed control is possible by adding more mulch on top of the fabric. Many gardeners add decorative wood or stone mulch to enhance its appearance. Application is similar to plastic, except that fabric is laid down after planting.
1. Clear area of existing weeds
2. Install fabric after planting so you can fit the fabric around plants
3. Anchor fabric with metal pins, leaving at least a 6″ overlap between pieces
4. Cover landscape fabric with mulch, if desired
Rubber mulch eliminates the need for annual mulching. This type of mulch is usually offered in natural-looking colors, such as redwood, terra cotta, brown or green. Rubber mulch is very effective at weed control and is heavier than wood mulch so it won’t float away. It’s often used in playgrounds because it is softer than some of the natural materials and has more give.
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