We typically think of bark chips or compost as mulch, but did you know that you can also use rubber, coconut fiber, and even cardboard?
There are many alternatives out there with differing textures, aesthetics, and benefits to suit your landscape.
Let’s look at 11 marvelous mulches and how to use them! Plus tips and guidance on mulch use in general.
Quick Guide To Using Mulch
Mulch should be dense enough to suppress weeds whilst aerated enough to send water and sunlight to the soil beneath. Some types do this better than others, but timely replenishing and applying the appropriate amount for your landscape size and needs will deliver the best results.
Organic Mulch vs. Inorganic Mulch
As once-living materials, organic mulch (grass clippings, leaves, compost etc) provides the soil with nutrients as they decompose and can attract pests. A regular need for replenishing will mean recurring costs unless you use your own yard waste materials.
Inorganic mulch, meanwhile, (gravel, shredded rubber etc) is a one-time purchase as it won’t break down and is low maintenance. Whilst it provides a neater aesthetic, some inorganic mulches absorb and reflect heat, which could damage sensitive nearby plants.
Purpose
Mulch not only prevents weed growth so plants can thrive without competition, but a mulch layer also helps retain soil moisture so you can water less frequently and also cools the soil in summer whilst providing insulation in winter.
Guidelines
- Fine mulch materials should generally be applied in 1-2 inch layers whilst coarse mulch should be applied to a thicker depth of 3-4 inches (or more if used purely for decorative, weed-suppressing purposes)
- Mulch should be kept 1-2 inches away from stems and trunks to prevent rot and pest infestations.
- If mulching close to your house foundations, inorganic over organic is best since wood-based materials can attract termites, breeding fungal spores which can enter your home – and as a rule of thumb, mulch layers should never be higher than your home’s foundations as you want water to flow away from your house!
- Organic mulch may need replacing every 5 years or as frequently as every 1-2 years depending on the level of foot traffic, heavy rainfall, sun exposure, and other factors that may accelerate decomposition.
- Beware that cocoa mulch (made from cocoa bean hulls) can be toxic to pets. Wood-based mulches are safest for curious chew-happy dogs – just supervise your pooch in case of choking or ingesting and be alert to any signs of an allergic reaction to the mulch.
TOP TIP: Be very careful when storing your wood-based mulch material (any wood or bark chips/shavings). Bagged mulch that remains wet or stored in tall piles (6-8ft or more) for long periods can “undergo anaerobic fermentation, converting organic matter into compounds such as ethanol and methanol which are released as gases which are toxic to plants” according to the University of Maryland.
Always store wood-based mulch in a dry, elevated area above the ground with good airflow and check the smell of any store-bought wood mulch before use: a sour, alcohol-like odor, as opposed to a pleasant earthy smell, suggests it has fermented in storage.
Landscape Fabric Under Mulch
As an extra weed suppression measure, some gardeners add a layer of woven fabric beneath the mulch layer. This can be beneficial in preventing heavier rock-based mulch from sinking into soil, initially permitting added airflow and water due to its tiny holes, and controlling soil erosion on sloped areas.
On the flip-side, landscape fabric is not a great permanent solution as its breathability declines over time, and replacing the fabric can be cumbersome and stressful for any plants that have grown above the fabric barrier.
1. Wood Chips and Bark Mulch
Spread wood chip/bark mulch over an existing organic layer such as leaves/compost and rake to the desired depth, taking care not to mix it in with the soil. Apply it around established plants only and keep it away from your house siding and vegetable beds.
Note that Cedar chips are great for repelling pests whilst Black Walnut mulch contains chemicals that may hinder seedling development and colored (dyed) mulch will fade over time
- Benefits: Great source of nutrients; regulates soil temperature; pest deterrent; controls topsoil erosion; attractive; great moisture-retention.
- Disadvantages: Draws nitrogen from soil; risks rot when combined with water-conserving compost; dyed mulch fades overtime; uncomfortable for barefoot traffic!
- Best used for: Well-established plants and beds; decorative paths/walkways
- Recommended depth: 4-6 inches
2. Sawdust
Add an inch of fresh sawdust on seed beds and around acid-loving plants like rhododendrons and blueberries or up to 2-inch layers for weed control. Sawdust can leach nitrogen from the soil, so consider adding nitrogen-rich fertilizer in spots near developing plants.
Replenish the sawdust yearly and use a rake to gently re-fluff the layer as it can soon become compacted and crust over, reducing airflow and moisture.
- Benefits: Prevents topsoil overheating in summer; promotes easy soil oxidation; inexpensive
- Disadvantages: Increases soil acidity with repeated use; robs soil of nitrogen; decomposes at a fast rate
- Best used for: Acid-loving plants; around walkways
- Recommended depth: 1-2 inches
3. Straw Mulch
Be sure to use weed-free straw mulch (not mixed in with hay as this can harbor weed seeds) and use a sharp shovel to break the bale into manageable pieces.
Apply the straw in 3-6 inch layers in between plant rows and individual plants, taking care to keep the straw clear from leaves to prevent the spread of fungus to crops. Replenish with a 2-3 inch layer each summer to prevent moisture loss.
- Benefits: Cheap and readily available; breaks down easily and provides nutrients; holds moisture well
- Disadvantages: Needs frequent replenishing; certain types may harbor weed seeds
- Best used for: Vegetable gardens, especially growing potatoes
- Recommended depth: 3-6 inches
4. Pine Straw
Wear protective gloves to handle the prickly needle-like texture and remove chunks from the bale, applying handfuls over walkways and 3-6 inches away from woody plant bases to prevent decay.
Spread in 3-inch layers in areas of regular garden soil or up 4-5 inches in sandy soils and replenish the pine straw layer yearly or twice a year for decorative applications.
- Benefits: Inexpensive; readily available; fights soil compaction and erosion
- Disadvantages: Can be an eye-sore; creates a highly acidic soil environment; not great for weed control
- Best used for: Acid-loving plants
- Recommended depth: 3-5 inches
5. Rock Mulch
Place two layers of landscape fabric over your chosen area to prevent the rocks from sinking into the soil and completely inhibit weed growth.
Shovel your chosen rocks/pebbles/gravel etc around flower beds, the bases of trees, ponds, or pathways, using a wide-toothed metal rake to spread the rock layer to the right depth. Finally, use a garden sprayer to rinse the rocks free of any accumulated dust.
- Benefits: Professional, decorative aesthetic; low-maintenance; weighty effective weed-suppressors; available in many different sizes/colors/textures
- Disadvantages: Absorbs a lot of heat in sunny gardens; very expensive upfront costs; larger stones can compact the soil; creates alkaline pH levels in soil over time
- Best used for: Decorative areas; shaded gardens
- Recommended depth: 3-4 inches
6. Lawn Clippings
Take care to add only a thin layer of fresh grass clippings (ideally 1/4-inch) as thicker layers remain too moist, inviting mold and a rotting smell before time.
For this reason, dried lawn clippings are best can be added in thicker layers (up to 2 inches). Mix them in with a layer of dried leaves for a nutrient-rich mulch layer for veg crops or lining garden pathways.
- Benefits: Nutrient-rich amendment; feeds worms and soil microbes; cuts down on yard waste; contains foliage-supporting nitrogen
- Disadvantages: Blows away in strong winds; thick, damp layers invite mold/odors; can attract pests
- Best used for: Veg crop patches; concealing exposed dirt areas
- Recommended depth: ¼-2 inches
7. Shredded Leaves
Use a mulching mower to shred dried, fallen leaves and create a finer layer as fresh, whole leaves can stop air and moisture getting to the soil.
Spread 2-3 inch layers over flower beds or up to 4 inches around the base of trees and shrubs. You can also mulch with composted leaf litter from the previous season which will break down more quickly into the soil.
- Benefits: Improves soil fertility; helps reduce soil erosion; eco-friendly; great moisture -retention; good soil temperature regulator
- Disadvantages: Leads to nitrogen deficiency in the soil; large quantities decay fast, causing soil in raised beds to noticeably sink
- Best used for: Insulating veg crops in winter
- Recommended depth: 2-4 inches
8. Rubber Mulch
If applying close to your home siding or other building structure, grade the designated lawn area first so it dips approx 1 inch per 10 feet to enhance drainage.
Install edging around the trench and place a layer of landscape fabric across the area. Lay 2-4 inches of the rubber mulch, tamping down the layer down lightly with your foot to even it out.
- Benefits: Low-maintenance; neat aesthetic; comfortable underfoot; holds up to extreme weather; won’t invite pests, moisture, or rot
- Disadvantages: High initial cost; higher flammability compared with organic mulch; high in zinc which can be toxic to certain plants, fauna, and beneficial fungi in the vicinity
- Best used for: Decorative areas close to house foundations; indoor garden decoration (sunrooms/solariums)
- Recommended depth: 2-4 inches
9. Coco Mulch
Coconut coir or coco mulch comes in compressed bales or bricks that expand up to seven times their size when water is added! So place bricks in 1-gallon buckets and soak in water for 15 minutes or place bales in wheelbarrows or plastic wading pools.
Once soaked, apply a 2-3 inch mulch layer as normal to your soil beds, but avoid mulching near acid-loving plants as coco mulch has a near-neutral pH.
- Benefits: Excellent moisture retention; sustainable; rich in carbon (great for balancing nitrogen-rich lawn clippings and compost layers); improves quality of compacted soils
- Disadvantages: Some coco bales are treated with chemicals; low in nutrients; can have a high-salt content
- Best used for: Alkaline and neutral pH plants and beds
- Recommended depth: 2-3 inches
10. Shredded Newspaper and Cardboard
Alone, newspaper shreddings and cardboard pieces are too dry and will blow away easily, so combine them with a layer of wood chips or compost.
Create a mulch of equal parts shredded newspaper and straw mulch or use large flat cardboard pieces, overlapping each section by at least 6 inches for adequate weed control. Once in place, wet the area with a sprinkler and add 2 inches of additional organic mulch to hold it in place.
- Benefits: Inexpensive; easily to source; great for trapping moisture; smothers weeds
- Disadvantages: Pests can make a home under cardboard layers; tricky to apply in windy weather
- Best used for: Shelter for seedling beds; pathways
- Recommended depth: 2-3 inches
11. Compost
Using store-bought compost or ensuring your own compost pile has fully cured (appearing dark and crumbly with a pleasant earthy aroma), you can start using it as mulch. Apply a fairly thick layer of around 2-4 inches around all your perennial beds, shrubs, or trees.
Add an extra 1-2 inch layer at the height of summer and again in fall to help keep the soil cool and well-insulated respectively.
- Benefits: Packed with nutrients; high-moisture retention; breathable; provides excellent winter insulation; enhances soil fertility and texture; eco-friendly
- Disadvantages: Expensive depending on yard/garden scale; time-consuming (if making your own); can attract pests
- Best used for: Insulating winter beds; general garden use
- Recommended depth: 2-4 inches
Conclusion
As you can see, no mulch is made the same – there are many options offering different advantages depending on your landscaping needs. Need a durable, fuss-free groundcover to circle your home siding? Inorganic rubber or rock mulch is a smart pick.
Perhaps you like the aesthetic of a wood chip pathway or need something to work in the favor of your fussy acid-loving azaleas and hydrangeas like sawdust and pine straw?
Whichever mulch you go for, be sure to apply it at the advised depth and away from stems, trunks, or foliage to prevent rot for a happy, healthy garden!