Weekend Project: Mulch your plant beds
Water quickly evaporates from bare soil. Mulching minimizes water loss, helps control weeds, and returns nutrients to the soil as it decomposes. Keep it replenished – it will help your garden look terrific.
Step One: Calculate how much mulch you need:
- Multiply the length of the area (in feet) you want to mulch by the width to get the approximate number of square feet.
- Decide how many inches deep you want to mulch. Typical mulch depth is about two to six inches.
- Mulch generally comes in bulk or bags, usually 2 cubic feet per bag. Use the following guide to estimate how much you need to add a 3” layer of mulch in your garden (modify accordingly if you prefer more than a 3” layer):
Area to be mulched Amt Needed
12 square feet 3 cu. ft.
24 square feet 6 cu. ft.
48 square feet 12 cu. ft
72 square feet 24 cu. ft.
Step 2: Choose mulches based on your preference and soil needs:
There is a wide selection of mulches for your garden. The most common types are shredded or ground bark and redwood mulch. Mulches may be organic or inorganic. Organic mulches decompose and over time enrich your soil. They need to be replenished periodically. Inorganic mulches last indefinitely. They are especially good for plants that prefer leaner soils, including many California native plants. For help choosing a mulch that best suits your needs, consult your local nursery. Some common types to consider are:
Wood chips/bark: Organic mulch is often made from wood chips or bark. Hardwood bark, cedar and redwood are long-lasting and attractive. For people who don’t frequently dig in their gardens this is a good alternative because medium or large bark pieces will stay on top of the soil and take longer to decompose. Soft woods like pine and finely chipped or shredded mulches decompose quickly and will need frequent replenishing.
Aged or composted animal manures: Effective for about one year. Make sure it is aged or composted as fresh manure can burn plant roots as well as contain weed seeds.
Agricultural by-products: Availability varies by region and may include mushroom compost, cocoa hulls, ground corncobs, straw or peanut hulls. Check your local garden center to see what is available and what is right for your soil.
Make your own mulch: Combine fallen leaves, twigs, pine needles and other small dry organic material. Add grass clippings (be sure they are free of lawn pesticides) or any other organic material. If leaves or twigs are large, chop them into smaller pieces. Using leaves or grass clippings, alone, can create a water-repelling mat if they are not mixed with other materials. (Do not use dried weeds, as the seeds may still be viable.)
Inorganic mulch: Decomposed granite, pea gravel, rocks and pebbles are all examples of inorganic mulch. Since they do not decompose you will not need to replenish them. They are especially useful for dry gardens featuring native and Mediterranean plants including those from desert and chaparral areas.
Step 3: Apply mulch
- Trim existing plants to improve shape and remove dead branches.
- Remove any weeds by digging them out to get the roots as well.
- Work in a soil amendment if you have poor soil: Add an organic soil amendment that is appropriate for your soil type. Mix the soil amendment into the top layer of soil, being careful that you do not disturb your plants’ root systems.
- Fix any sprinkler heads that may be clogged, broken or out of alignment.
- Smooth out your garden bed and build shallow soil berms around shrubs and trees to hold irrigation water.
- Apply mulch evenly: Keep mulch away from the base of shrubs and trees to prevent moisture from building up and causing decay and disease.
- Gently water the mulch after the first application.
- Mulch reduces your watering needs, so change your irrigation schedule to reflect the new conditions. Remember more plants die from too much water than too little.
- Check your mulch regularly and replenish it when necessary If fungus develops, remove the fungus areas, dig to loosen up the mulch soil, then add new mulch. Water thoroughly but infrequently to keep your plants healthy and avoid soil diseases.