A Brief Guide to 13 Common Garden Mulches

A Brief Guide to 13 Common MulchesYou don’t have to read many gardening books or websites to catch on that mulch is highly recommended for all gardens. But knowing that you ought to mulch your garden and deciding what to mulch it with are two different things.

First off, it is important to recognize that everyone’s circumstances are unique. Factors that will affect your choice of a mulch include:

  • Your purpose for mulching.
  • The types of plants you will mulch.
  • The materials available in your area.
  • The cost of the different local materials.

Therefore, it is a good idea to know going in exactly what you are trying to accomplish, whether that is weed control or soil improvement.

Once you have a clear objective for mulching, then it’s time to choose the material, or perhaps several materials for different beds and purposes.

You are ready to weigh the pros and cons of the most common mulch materials.

Straw

Straw and hay are not the same. Straw is simply crop stubble, while hay is the entire grass plant, including seed heads. Straw is an effective weed barrier, while hay is primarily a simple mechanism for introducing a host of new weeds to your garden. Make sure you mulch with straw, not hay.

Pros:

  • Readily available.
  • Generally cheap.
  • Generally attractive.
  • Controls weeds well if applied thick enough.
  • Protects plants from frost.
  • Cools the soil in hot weather.
  • Improves soil texture.
  • Retains soil moisture extremely well.
  • Prevents soil erosion.
  • Decomposes slowly.

Cons:

  • Attracts rodents.
  • May attract slugs in cool, wet climates.
  • May contain weed seeds.
  • May contain mold.

Best Application: General-purpose vegetable garden mulching, summer through winter.

Lawn Clippings

Lawn clippings should be used with care. They should be applied only when dry and preferably in conjunction with coarser materials to avoid forming a heavy, moldy, anaerobic mat. Also, if accepting bagged lawn clippings from other people, always check to make sure that they do not use herbicides, as accidental contamination can spell speedy death to your flowers and vegetables.

Pros:

  • Readily available for free.
  • Adds nitrogen to the soil.
  • Controls weeds well provided it does not contain weed seed.
  • Conserves soil moisture.

Cons:

  • May be contaminated with herbicides and other chemicals.
  • May contain weed seed.
  • Molds readily if applied too thickly or when damp.
  • May produce odor if applied too thickly or when damp.
  • Forms a water-repellent mat if applied when damp.
  • Decomposes extremely quickly.

Best Application: Mulching summer vegetables with high nitrogen requirements.

A Brief Guide to 13 Common Garden MulchesLeaves

Leaves can improve your soil texture and nutrient profile in an amazingly short amount of time. Unfortunately, they can also be difficult to manage in the garden, as they blow away when dry and form heavy, waterproof mats when wet. Want to avoid some of the problems associated with using leaves as mulch? Shred or partially compost the leaves before applying them. As a final word of warning—do not use walnut leaves, as they are toxic to many plants.

Pros:

  • Readily available for free.
  • Protects plants from frost.
  • Cools the soil in summer.
  • Retains soil moisture very well.
  • Improves soil texture.
  • Adds many nutrients to the soil.
  • Promotes earthworm health.

Cons:

  • Tends to blow away.
  • May contain plant diseases, depending on the source.
  • May form a water-repellent mat after rainfall.
  • May deplete soil nitrogen in the short term unless partially composted.

Best Application: Protecting and enriching vegetable garden soil over the winter.

Pine Straw/Needles

Pine straw is just pine needles used for mulch.

Pros:

  • Free or cheap.
  • Attractive.
  • Controls weeds effectively.
  • Improves soil texture and drainage.
  • Prevents soil erosion.
  • Permits water penetration.
  • Decomposes slowly.

Cons:

  • Painful to handle—wear gloves.
  • Makes soil too acidic for many plants.
  • Inhibits earthworm activity.

Best Application: Mulching acid-loving plants such as blueberries, hydrangeas, or rhododendrons.

Wood Chips or Bark

There are many varieties of wood mulch to choose from, all with their own unique benefits. Cedar even provides a certain level of protection from insects. Just watch out for toxins—if you purchase your wood mulch, stay away from mulches containing dyes. Also, never use black walnut, as it contains toxins lethal to many garden plants.

Pros:

  • Readily available, sometimes for free.
  • Attractive.
  • Controls weeds effectively.
  • Retains soil moisture fairly well.
  • Adds nutrients to the soil in the long term.
  • Decomposes very slowly.

Cons:

  • Sometimes contains dyes.
  • May float away during heavy rainfalls.
  • Depletes soil nitrogen in the short term.

Best Application: Ground cover for perennial beds.

A Brief Guide to 13 Common Garden MulchesCompost

Don’t have your own compost pile? You can purchase bagged compost at garden centers, but commercial compost is typically made with only a couple of ingredients and is thus less balanced than homemade compost.

Pros:

  • Can be made at home for free.
  • Improves soil texture considerably.
  • Provides valuable soil nutrients.
  • Builds the soil microbe community.

Cons:

  • May contain plant diseases unless produced using the hot composting method.
  • Provides only partial weed control.
  • Breaks down quickly.

Best Application: Feeding garden plants of all types under another mulch material.

Peat/Sphagnum Moss

Peat moss is harvested from peat bogs. It has some unusual characteristics that can be either good or bad depending on your requirements. For one thing, it can absorb water like a sponge, which improves boggy soil considerably but may allow plants to dry out in hot, droughty weather. For another thing, it makes the soil more acidic, although typically not enough to present a problem.

Pros:

  • Readily available.
  • Improves soil texture and drainage considerably.
  • Decomposes very slowly.

Cons:

  • Prone to blowing away if dry.
  • Provides no soil nutrients.
  • May hinder water penetration if applied too thickly.

Best Application: Improving heavy soils that drain poorly.

Sawdust

If you do plenty of woodworking, sawdust is definitely a mulch you should consider. Just be careful about what sawdust you use—dust from treated lumber can add toxins to your soil.

Pros:

  • Can be obtained for free.
  • Controls weeds well if applied thickly enough.

Cons:

  • Forms a water-repellent crust after a rain.
  • May make the soil too acidic for some plants.
  • May deplete soil nitrogen levels.
  • Breaks down quickly.

Best Application: Mulching acid-loving plants for cheap.

Cardboard

Cardboard is the go-to mulch if you have a serious weed problem—nothing can penetrate it! Keep in mind, though, that cardboard can be a pain to deal with. You will want large sheets to cover as much surface area as possible without leaving cracks for weeds to grow through, and you will want to cover it with straw to keep it in place but out of sight.

Pros:

  • Readily available, often for free.
  • Controls weeds extremely effectively.

Cons:

  • Extremely unattractive unless completely covered by another mulch material.
  • Makes it impossible to add new plants without removing the mulch.
  • May cause boron toxicity due to glue; soak in water before using, then discard water (or use it as a fertilizer for strawberries).

Best Application: Putting the brakes on heavy weed infestations in perennial beds when used in combination with another mulch material.

Newspaper

While many gardeners avoid mulching with newspaper for fear of lead contamination, newspapers phased out lead-based inks long ago. Black-and-white newsprint is perfectly safe for the garden these days; colored inks may still contain some heavy metals. Note that newspaper is prone to blowing around. Cover it with another mulch, such as straw or wood chips, to avoid inadvertently trashing the neighborhood.

Pros:

  • Readily available.
  • Cools the soil in summer.
  • Controls weeds effectively.

Cons:

  • Hard to keep in place.
  • Very unattractive unless thoroughly covered.
  • May contain heavy metals if colored ink was used.

Best Application: Preventing weed growth between rows in a vegetable garden when combined with straw or another mulch material.

Pea Gravel and Crushed Rock

A rock mulch is about as permanent as it gets, and it can be very attractive in landscaping. Keep in mind, however, that rock works best with heat-loving plants. It is a popular choice of mulch in cactus gardens.

Pros:

  • Fairly cheap.
  • Attractive if done well.
  • Allows water penetration.
  • Lasts a very long time.

Cons:

  • Will scatter unless contained with edging.
  • Provides no nutrients to the soil.
  • Makes improving the soil underneath impossible.
  • Provides only partial weed control.
  • Makes pulling weeds that penetrate the mulch more difficult.
  • Cooks shallow-rooted plants in hot weather.

Best Application: Around woody perennials or in desert landscaping.

A Brief Guide to 13 Common Garden MulchesPlastic

Plastic mulches come in several different colors. Black plastic is effective at warming the soil. Clear plastic warms the soil even faster, but has the disadvantage of permitting weed growth. Red plastic reflects certain wavelengths of sunlight onto the plants, enhancing the yields of tomatoes and other summer vegetables. Whatever type of plastic you use, remember that rain cannot penetrate to the soil, so you will need to combine the plastic with soaker hoses or a similar form of irrigation.

Pros:

  • Readily available.
  • Warms the soil by 5 to 20 degrees, depending on the color.
  • Makes an effective weed barrier, depending on the color.
  • Retains moisture extremely well.
  • Increases the yield of heat-loving crops like tomatoes and peppers.

Cons:

  • Will blow away unless weighted down.
  • Provides no nutrients to the soil.
  • Makes improving the soil underneath difficult.
  • Prevents water penetration.
  • Overheats the soil in hot weather.
  • Creates an anaerobic environment toxic to plants.
  • Becomes brittle when exposed to sunlight unless covered with another mulch material.

Best Application: Warming the soil in the spring, particularly around warm-season vegetables.

Landscape Fabric (Geotextile)

Landscape fabric should be covered with another mulch material for both looks and longevity. Keep in mind that some weeds can grow through the fabric.

Pros:

  • Permits air and water to enter the soil.
  • Suppresses most (but not all) weeds.
  • Lasts many years if protected with rocks or wood chips.

Cons:

  • Expensive.
  • Makes adding new plants to the landscape more difficult.
  • Makes pulling weeds that penetrate the fabric more difficult.
  • Inhibits earthworm activity.

Best Application: Around landscaping perennials.