Mulch is anything that covers the surface of garden to keep moisture in the soil and keep weeds down. The best garden mulches for home gardeners are organic materials derived from nature. Gardens can be mulched with materials such as compost, shredded arborist wood chips, pine needles, or even tree bark.
The Best Garden Mulch: Compost
Fall leaves, grass clippings, and coffee grounds can be composted at home to create a beautiful, dark compost mulch that looks sharp in well-tended veggie and perennial garden beds. Homemade compost is a top mulch choice for experienced organic gardeners.
Compost can also be purchased in bulk at nurseries and landscape suppliers. This compost is generally a well-composted mix of shredded trees, herbivore animal manure, and excess agricultural products such as grain silage.
Like all organic mulches, compost can be applied at least 1″ thick, and should be kept about 6″ from tree trunks and building foundations. The 1″ thick layer of compost is great for keeping moisture in (great for plant roots, but not so great for plant bark or buildings….).
Black mulch is a favourite mulch product of garden and landscape designers. The dark colour of the mulch compliments plants and really makes the greenery “pop”. It also camouflages any stray garden soil well and is relatively easy to maintain.
Look for a black mulch that is naturally dark in colour (rather than dyed with industrial chemicals). Mulch ingredients like rich compost, charcoal, and certain types of composted manure can add to the dark appearance of black mulch (without added dyes).
Wood Mulch – Arborist Wood Chips
Tree prunings can be shredded into wood mulch (leaves and all!). Shredded arborist mulch is often cheaper than compost because nurseries receive the material for free from tree trimmers looking to save on disposal fees at the dump. If you do choose a wood mulch, choose a mulch that includes the whole plant (leaves and all). Straight wood mulches should only be used in areas where plant growth is unwanted, as they rob the soil of nitrogen required by plants.
Organic commercial mulches are also available, both in small bags and for bulk mulch delivery. Look for a wood mulch that’s certified to be free of chemicals like pesticides, fungicides, and herbicides. Dyed mulches should also be avoided!
Inorganic mulches such as plastic or textile sheeting are also used in some large market gardens and small organic farms. Sheeting is generally used as a utility mulch in these commercial applications as it doesn’t really enhance the look of the garden. If you just want to grow rows of flowers for bouquets or veggies to can/sell, and don’t care much about the plastic showing, sheeting may be right for you.
Cedar Mulch – Bark Mulch
Cedar mulch is made of shredded or chipped cedar tree bark. Cedar mulch lasts much longer than other types of bark mulch because cedar is resistant to decay. Cedar decomposes much more slowly than other common types of wood or composted mulches. It also has a nice warm natural colour and fresh scent. Avoid “cedar mulch” made from other (cheaper) types of wood that have been dyed to look like cedar.
Cedar mulch, like all wood mulches, uses up nitrogen in the surrounding soil as it slowly decomposes. This can “rob” nearby plants of the nitrogen they need. If using cedar mulch, your plants will likely need regular application of a quality organic fertilizer.
Types of Mulch to Avoid
Avoid garden mulch made from industrial byproducts such as lumber wood chips or rubber tires. Any chemically-dyed mulches are also a no-go. Wood chips, sawdust, and root mulches have also been known to import artillery fungi which love to shoot sticky dark spores onto siding and fences (not so nice…).
Recycled industrial materials like rubber mulch are generally discouraged by home gardeners, as they can leach industrial chemicals into your garden (and make it smell like a hot racetrack in the summer). There are appropriate ways to recycle rubber tires (including into surface coverings) but home garden mulch isn’t one of them. If you have to pay a bunch of money to get rid of something (and go to a specialized disposal area), it’s generally not worth paying for as garden mulch.
Chemically-treated natural mulches should also be avoided. This includes many wood mulches made from scrap lumber such as pallets. Some of this wood has been treated with chemicals like fungicides which are detrimental to garden health. Wood mulch made of scrap wood chips is often dyed as a way to sell it as a higher price. Avoid mulches that look like they’ve been dyed green, red, or black.
Lastly, avoid mulches which may contain living weed seeds. This includes hay, straw, poorly-composted animal manures, and poorly-composted yard waste.