Nature’s mulch

Organic mulches not only cover garden soil, they become garden soil, eventually feeding the plants they protect. The downside: you must re-mulch every spring and, preferably, in late fall to protect plants from a deep freeze.

Shredded leaves: This waste-not mulching uses autumn leaves to protect plants all year long. You can mulch leaves by running them through a shredder to produce a uniform and handsome mulch that quickly decomposes. Or just rake the leaves into plant beds and kill two gardening chores with one stroke. Cost: Free

Pine needles:
Pine needles are handsome, smell great, and lower soil pH. Gather needles from under your evergreens and lightly spread them around acid-loving shrubs, like azaleas. Cost: Free

Grass clippings: If you mow your lawn, you’ve got nitrogen-rich mulch that quickly decomposes and nourishes plants. Let clippings dry in the sun before lightly spreading them in your garden. Cost: Free

Straw: Often used to mulch newly seeded lawns, straw mulch forms a loose layer of protection against soil erosion. It’s inexpensive garden mulch that you can work into the soil in September, where it decomposes and feeds your plants throughout the year. Warning: Don’t confuse straw with hay; put hay on your garden and you’ll likely pluck hay seeds and weeds all summer. $6/bale average.

Shredded hardwood: This mulch contains shredded bark and wood, decomposes quickly, and provides an attractive ground cover. It’s great at keeping down weeds, and making the ones that do pop up easy to pluck. You can buy it as natural color or dyed in brown, black, and red. Many cities give this type of mulch away, although it may be shredded from diseased trees. To be safe, buy it at big box stores. $3.30/2 cu. ft.

Shredded hardwood bark: Consistent color and size makes this the most popular mulch to lay around foundation plants. It has an earthy smell and decomposes quickly, so it must be replenished at least annually. $3.85/2 cu. ft.

Wood chips/nuggets: Great around trees and shrubs, and creates a lovely home for worms, nature’s soil tillers that reduce compaction. Chips are good at retaining water, but bad at decomposing, so don’t use them in flower beds and vegetable gardens. $2.80/ 2 cu. ft.

Rock:
Spread rock mulch over landscape paper in plant-free areas, such as paths or around fountains. It won’t blow away or decompose, so this mulch will last almost forever — which it should, because it’s expensive. $3.50/0.5 cu. ft.

Man-made mulch

Inorganic mulch conserves moisture and regulates soil temperature, often better than organic mulches. Most types prevent soil from splashing on leaves, and survive more than one season. Their biggest disadvantage is that they look unnatural, so you must cover them with an organic mulch, driving up the price.

Plastic: Black plastic mulch ($3/50 ft.) is good for regulating soil temperature, conserving water, suppressing common weeds, and keeping away pests. Red reflective plastic ($15/25 ft.) mulch reportedly increases strawberry and tomato yields, sometimes by 20%. Clear plastic helps heat soil, which kills soil pathogens and weed seeds. ($70/600 ft.)

Newspaper: Great for keeping down weeds in garden paths; not so good at letting oxygen and water nourish garden plants. Place one or two layers in paths; water to keep it in place; then cover with more attractive mulch, such as shredded hardwood. If you’re worried about toxic chemicals even in soy-based newspaper ink (most papers use soy), lay newspaper mulch in paths and other areas away from growing food. Free (if you subscribe)

Recycled rubber: Hailed as the last mulch you’ll ever need, rubber mulch from recycled tires is controversial. Some say rubber mulch doesn’t do much to keep down weeds, is highly flammable, and possibly may leach toxic chemicals. So, it’s best to use this mulch in play areas where it does a good job cushioning falls; but keep it out of your garden. $8.90/0.8 cu. ft.