How to Mulch Your Garden | Types of Mulch (2024)

Time to mulch! Most of us know the amazing benefits of mulch in the garden. But when should you mulch? How much should you mulch? Can you mulch too much? What type of mulch is best? See our guide on how to mulch your garden beds andplants.

Mulch has been called the gardener’s friend—and for goodreason.

• In the spring, mulch retains moisture, suppresses weeds, and preventserosion.
• In the fall, we re-apply mulch for the same reasons. But we prefer fall mulching because it’s organic matter that will disintegrate into the warm soil, providing both nutrients and organic content to improve yoursoil.
• Fall mulch also works through winter, protecting bare soil from free-thaw patterns and insulating the plantroots.

What IsMulch?

At its simplest, mulch is anymaterial that covers the soil’s surface. In nature, mulch is simply fallen leaves and plant debris. In the garden, mulch can also includecompost, wood chips, rotted manure, cardboard, or evenseaweed.

It’s only recently that we’ve come to appreciate mulch’s sustainable and ecological benefits. Done correctly, mulching feeds our soil’s living microorganisms with nutrients, and the waste from these tiny microbes creates a healthier soil structure for plants, limitingcompaction.

The Benefits of Mulching: Why Should IMulch?

1. Reduces weed growth by keeping light from reaching the soilsurface.
2. Reduces water loss from the soil surface, which helps maintain soilmoisture.
3. Moderates soil temperatures, keeping it warmer on cold nights and cooler on hotdays.
4. Protects bare soil, reducing erosion and soilcompaction.
5. Protects plants from the harsh conditions of winter freezes, thaws, andwinds.

There aremany other benefits ofmulch:

• In winter, the soil under the mulch will be warmer than unprotected soil. This protects plants from the cycle of freezing and thawing (which can heave them out of theground).
• Prevents crusting of the soil surface. Water moves more readily into soil covered with mulch instead of runningoff.
• Keeps soil from splashing onto leaves; keeping soil off leaves reduces the chance of plants gettingfungal and bacterialdiseases.
• Breaks down and feeds the soil (if organicmulch).
• Improves the structure of clay soils and the moisture-holding capacity of sandysoils.
• Slowly increases soil fertility (if organic) and may make micronutrients already in the soil moreavailable.
• Warms the soil in spring, allowing the gardener to plantdays or weeks before the soilwould normally beready.
• Keeps plants clean and off the ground, especially tomatoes and melons, to avoid plantdisease.
• Limits the chance of damaging trees’ trunks when mulch is placed around them instead ofgrass.
• Improves plant health and growth (due to fewer weeds andmore consistentmoistureand soiltemperature).
• Makesgardens “spiffed up” and attractive, giving a uniform appearance and rhythm to gardendesign.

Disadvantages ofMulching

Although using mulch has many benefits, in some cases, its usecanbe detrimental to thegarden:

• Do not over-mulch. Aim to apply a 2- to 3-inch-thick mulch layer. More than that amount will bury and suffocate plants; water and oxygen can’t reachtheroots.
• Don’t layer mulch deeply over perennial plant crowns (the growingpoints).
• Don’t pile up mulch near the trunks of trees and shrubs. Keep mulch 6 to 12 inches away from thebase of woody plants to avoid rot,wood-boring insects, gnawing rodents, anddecay.
• If you have perennial gardens, don’t apply fall mulch too early. Wait until after the first hard freeze after you cut down perennials; be sure to leave some perennial stems for nativeinsects.
• Light-colored, wood-based mulches, like sawdust or fresh wood chips, 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. (Learn more about soil amendments.)

How Much Mulch Do INeed?

With most organic mulches, a layer of 2to 3inches is plenty. The finer the material, the thinner the layerneeded.

Inorganic mulch is often more shallow. For example, a mulch of small stones usually only needs to be an inchdeep.

1 cubic yard = 27 cubicfeet

Types ofMulch

The ideal mulch needs to trap air to provide insulation and warmth, similar to down in a winter coat. It needs to be dense enough to block weed growth but light enough to allow water to reach the soil. Both organic and inorganic mulches can be used effectively in thegarden.

OrganicMulches

Organic mulches are natural products from leaves, trees, grass, and other plant material, often from your own yard. They mimic nature, breaking down gradually over time. The advantage is that they are truly adding organic matter to the soil. The disadvantage is that they must be replenishedperiodically.

1. Shredded bark. Softwood bark mulch is attractive, resists compaction, and breaks down slowly. Hardwood bark is attractive but breaks down quickly and needs to be properly composted to avoid sour mulch and nuisancefungi.
2. Shredded leaves are readily available and, if chopped, eventually break down and feed the soil with beneficial materials. The disadvantage is that leaves can mat if wet which reduces the oxygen and moisture in the soil. Avoid matted layers of wetleaves.
3. Weed-free strawand salt marsh hay are inexpensive and helpful covering; however, they decompose more quickly, may harbor rodents, and are easily blown away by thewind.
4. Pine and cypress needles are attractive and stay in place better than most mulches. They are slow to break down and aren’t as acidic as you might expect, so don’t worry about them changing the soil’spH.
5. Local byproducts, such as spent hops from a brewery, cocoahulls, ground corncobs, coffee grounds, newspaper, or cardboard can also be much.Getcreative!

InorganicMulches

• Black plastic mulchhelps warm the soil in spring, reduces water loss, and is convenient. This can make a big difference in short growing seasons. However, it’s not permeable, so it’s more difficult to water; it also breaks down when exposed to sunlight, and the soil under the plastic becomes very hot in the middle of summer if not shaded by leaves or covered with anothermulch.
• Silver plastic mulch excels at warming soil in spring but doesn’t control weeds; the soil becomes even hotter with clear plastic in midsummer, and plants can be damaged if the plastic is notshaded.
• Crushed stone, gravel, marble, or brick chips provide permanent mulch around shrubs and trees. That said, these mulches are expensive, hard to move, and can get into the lawn. Weed seeds and soil can still find their way into the stones; an underlayer of landscape fabric will help preventthis.
• Landscape fabric smothers weeds while allowing air, fertilizer,and water to move through it and into the soil. It is treated to resist decomposition and helps retain soil moisture. It’s important to fasten the fabric down so perennial weeds do not push itup.

How to ApplyMulch

Mulching inSpring

Remove winter mulch in the spring when the danger of a hard frost is past so that the ground can warm and new growth will not beinhibited.

If there are many weeds on the ground where you want to grow, consider installing permeable landscape fabric on many of thebeds.

Or, lay down a layer of cardboard before adding your organic matter. Thoroughly wet the cardboard to help it break down. The cardboard will serve as a further barrier to weeds, exhausting and eventually killing most of them. Once the growing season gets underway, you’ll find that any weeds that do manage to make it through will be much easier toremove.

After a few spring rains, when the soil has warmed, we lay down soaker hoses in eachbed.

Then, we cover the hoses with a fabric to speed up the change in soil temperatures and warmthe soil for earlierplanting.

Planting holes are cut at different spacings for different crops. Watering is efficient,and maintenance of a large area is made mucheasier.

Once the plants get some size on them, the fabric is covered and does not look so bad! We also use organic mulch, including straw, leaf mold, grass clippings, wood chips, and shredded leaves for crops that arecooler.

Regularly mulchwith organic matter.Replace old mulch as it rots down or becomes incorporated into the soil so that the ground is constantly fed and gradually builtup.

Mulching inAutumn

We do not generally use mulch in the fall, except for in bare, unplanted garden beds to prevent erosion. If you did not plant a winter cover crop (which you would till under in the spring), you should spreada thick layer of soil-conditioning compost or well-rotted organic matter over the bare soil. You could also use shredded leaves.Lay it at least fourinchesdeep.

Otherwise, do not apply mulch to your landscape in autumn. The soil will not cool down quickly, and plants may continue to grow. New growth may not harden off and can be damaged by winter cold. Also, mulching in the fall keeps the soil wet, which can lead to root rot and plantdeath.

Note: If you’re setting out new areas, start by clearing the surface of any debris and any rocks larger than a hen’s egg. Mow down grass or cut back weeds to the ground. Fast forward a few months, and any grass and weeds below will have rotted down, while earthworms will work to gradually incorporate the organic matter into the soilbelow.

Mulching inWinter

Once you’ve had several freezes (often around Thanksgiving or after), apply winter mulch around the base of any tender perennial plants or new plants.Grafted plants, like hybrid tea roses, benefit from being mulchedheavily.

Shredded mulch, straw, pine needles, or shredded leaves are all good winter mulch.Apply 3 to 4 inches. It’s important to apply enough mulch in winter to keep the frozen ground completely covered so the plant remains dormant until spring no matter what type of warm or cold spellsoccur.

Take care NOT to put mulch next to the trunks of trees or crowns of plants, as thisinvites bark-gnawingrodents.

Protect branches and buds of evergreen or semi-evergreen shrubs such asrhododendrons and viburnumsby wrapping them with burlap or protecting them with a tree guard filled with shredded leavesforinsulation.

Check out our guide to composting!

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