‘Scavenged’ cardboard boxes make an ideal weed barrier. They can be found at appliance stores or bike shops.
Sheet Mulch Catalog
B-flute cardboard rolls work well for covering large lawns. Comes in 1,000 square foot rolls, available in bulk from vendors in the Marketplace.
Arbor mulch works great for lawn conversions and can be made from many kinds of trees. Available in bulk from vendors in the Marketplace.
Made from used pallets or used lumber, this mulch breaks down slowly and is recommended for pathways. Available in bulk from vendors in the Marketplace.
Made from chipped trees, brush, and other plant trimmings, this mulch provides nutrients to build healthy soil, but doesn't last as long as arbor mulch. Available from local tree trimmers.
Frequently Asked Questions about Sheet Mulching Materials
Why use recycled compost and mulch?
When you use recycled compost and mulch, you are closing the loop. The compost listed in the marketplace is made from plant trimmings and food scraps here in the Bay Area and the mulch is chipped from untreated wood pallets and tree trimmings. The waste generated is recycled into products that will feed nutrients back into your soil for planting perennials and edibles, as well as helping convert a lawn into a garden.
Isn’t all compost organic?
Not all compost is created equal. To ensure the compost does not include biosolids, we work with vendors who sell compost that has been certified by a third party. The three certifications to look for:
- OMRI listed products undergo review to ensure that they comply with national organic standards.
- CDFA – California Department of Food and Agriculture.
What is the best mulch to use for lawn conversion with sheet mulching?
The optimum mulch for lawn conversion is coarse recycled mulch – either pallet mulch from chipped pallets or arbor mulch from tree trimmings. Coarse mulch will prevent weeds and takes longer to decompose. We don’t recommend guerilla hair because it is forest product and can be a fire starter. Coarse mulch is also ideal for pathways. Finer mulch is better for edibles and raised beds applied in a thin layer – 1 inch or less. Fine mulches include straw, grape hulls, and compost.
Who makes the compost and chips the mulch?
The producers of the listed compost process food scraps and plant trimmings. The pallet mulch is chipped from untreated clean wood pallets and colored with vegetable based dyes. The arbor mulch is chipped from trees.
The producers/brands for the marketplace compost and pallet mulch are:
- Earth Care – Waste Management
- Super Humus Compost and Pro-Chip Mulch – Republic Services
- Z-Best and Pro-Chip – Zanker
- Recology Organics
Are tree trimmings okay to use as mulch?
Tree trimmings are a good recycled mulch option and you can often get them for free from local arborists. Please note that the tree trimmers will drop a full load – up to 20 cubic yards and the availability of this mulch is seasonal. Make sure to ask about the source of the tree trimmings, do not accept any diseased tree trimmings, and avoid Euculyptus and Black Walnut. If you can't find a good source of tree trimmings, several vendors on the marketplace carry arbor mulch.
How much compost and mulch should I get?
For lawn conversion, we recommend 1.5 inches of compost, 3 inches of mulch and 2 layers of rolled cardboard. To specify to your own yard, use the materials calculator.
What is B flute cardboard and why is it listed?
B Flute cardboard comes in rolls (3-6 ft. wide) and is an ideal layer for sheet mulching to convert a lawn and/or suppress weeds. It’s thick enough to block sunlight from reaching grass or weeds. Rolls 3-4 feet wide are easiest to maneuver; larger rolls cover more ground faster, but usually take a team of 2 to carry and lay out.
Where can I find free, scavenged cardboard, and how do I estimate if I have enough?
Scavenged cardboard boxes are thicker than B-flute cardboard and make a long lasting weed barrier. However, finding enough scavenged cardboard for your project will likely require you to gather from multiple sources. Bike shops and appliance stores frequently receive their products in large boxes, and rather than pay to recycle the boxes, they are usually happy to save money by giving cardboard away! The typical bike box is 43x11x32 inches, or 75x43 inches when laid out flat. Taking into account overlapping the cardboard weed barrier by 6-8 inches, plan to scavenge ~8 bike boxes for every 100 sq ft you are sheet mulching.
There are several vendors in the Bay Area who sell compost by the cubic yard and deliver it in a dump truck. If you have a large gardening or landscaping project, then buying compost in bulk can be very cost effective. Since compost quality can vary from batch to batch you should make sure you will receive a quality product before the dump truck arrives. The best way is to visit the vendor and check out the bunkers full of material. Keep in mind that although vendors often display compost samples, this material may be from a different batch and might not represent what you will get. If you can’t see the compost before ordering a delivery, make sure to check the material in the truck BEFORE they dump it. If it is poor quality, then you can refuse the delivery and send it back.
Ask the vendor if the compost is OMRI-listed or CDFA-registered as organic compost. You can feel confident about compost that meets these standards.
Check the compost for the following:
- It should be dark, more black than brown in color, and have a crumbly rather than woody texture. Woody compost can still be used as a mulch or in sheet mulching but is not ideal if you are using in a vegetable garden.
- Grab a handful and smell the compost. It should smell sweet and earthy. A slight smell of ammonia is okay. It should not smell putrid or strongly of ammonia.
- It might be warm or steaming; that’s okay. However, if it’s very hot that means the material is still actively composting and you will need to wait until it cools down before applying around plants.
- It should not contain large amounts of plastics, metals, and other contaminants.
- If you accept the compost, place a tarp down where it will be dumped.