Q&A: Mulch Basics

No matter what condition your garden is in, adding a layer of mulch will give it a clean, freshly planted look. But the benefits of mulch are not just cosmetic. Mulching is one of the best ways to maintain soil moisture (and to save on your water bill), insulate roots from both heat and cold, and minimize the need to weed. Here’s what you need to know to get started. Q: What exactly is mulch? A: Generally speaking, mulch is any material that protects soil surface and allows air and water through. Mulch is useful over an area of bare soil and around planted areas. Organic mulches (derived from plant material) add nutrients over time and enrich overall soil composition, so they’re hard to beat. Compost, aged manure, raked leaves, pine needles, and thin layers of lawn clippings (as long as they’re herbicide and pesticide free) all work for various situations. You can also opt for an inorganic mulch such as gravel, granite, or stone. Q: Will manure burn my plants? A: It can burn the roots of your plants if it’s not well composted, so look for bag labels that specifically say “well-composted manure.” Be sure to ask your supplier if you are purchasing in bulk. Q: How much should I buy? A: Determine the square footage you want to cover and use the following as a guide: A 2-cubic-foot bag covers an area of 8 square feet that’s 3 inches deep; 1 cubic yard of mulch covers an area of 108 square feet, 3 inches deep. Q: How thickly should I apply the mulch? A: In general, the denser the mulch particles, the less you need. Q: Any application tips? A: Spread mulch to the appropriate thickness, taking care to keep it a few inches away from tree trunks and the crowns and stems of plants. If placed too closely, mulch can retain moisture and cause plants and trees to rot. Q: How can I keep my mulch clean? A: Inevitably, leaves and other debris will fall on your mulch. You can remove litter with a small hand rake. Some people use blowers, but lighter mulches may blow away along with unwanted material. Q: When should I mulch? A: At least once a year in early spring before weeds sprout. You can also add a second layer as a top dressing in late fall. Q: When do I remove it? A: You can leave mulch in place indefinitely. Just scrape it aside if you want to plant in a mulched area. Q: What’s the best way to mulch container plants? A: Use the same depth and application technique as for mulching on the ground. Six of our favorite mulches Depending on your garden situation, many materials can make great mulches. The following are widely available in bags or in bulk from nurseries and landscape supply centers: Straw. Light, loose option lets water pass through easily; good around vegetable and strawberry beds. Buy at livestock-feed stores. Don’t use hay, which has seed heads that may germinate into weeds. Apply 4-5 inches. Hazelnut hulls. Good for general use and ideal for paths because hulls let water through easily and don’t stick to shoes. Most readily available in and around Oregon’s Willamette Valley. Apply 2-3 inches. Cut bark. Made from different types of wood based on where you live; a good all-purpose choice. The mini size shown here gives landscapes a polished look. Apply small-size 2-3 inches; larger, 4-5 inches. Decomposed granite (DG). Compacts quickly and doesn’t tend to blow away. Especially attractive in Southwestern and desert landscapes, but can be prone to weeds. Apply 1-2 inches. Shredded bark. Slow to decompose, with a more woodsy, natural look than cut bark. Irregular bits and shredded pieces knit together so it stays in place. Useful on slopes and in windy areas. Apply 2 inches. Tumbled glass. Pricey ($3-$7 a pound or more), so used mainly to add color and punch to small areas.