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  • Writer's pictureMatt Suprunowicz

How to Mulch Your Garden

Updated: Jul 31, 2023

How do ground covers improve the fertility of the garden ?


This Lesson Plan is part the Gardening Module of SustainEd Farms' virtual programming.

Background: Mulching Your Garden

Mulching is an essential garden practice for improving the quality of both soil and plant life. Mulching includes practices such as compost treatments, planting other living plants to cover soil area, applying layers of leaves, straw, or bark, and even spreading inorganic covers such as gravel and plastic sheeting. Simply, mulch is any layer of ground cover that can be used to improve the function of the garden’s (or farm’s) ecosystem. If the materials are available -- you may consider growing and/or harvesting your own -- mulching your garden can be done in little time while using few tools.

Learning Objectives

Students will be able to...

  • Apply a mulch layer to a garden bed

  • Understand the many benefits of using mulch in a growing space

Academic Vocabulary

buffer /ˈbəfər/ noun/verb. - the mechanism that prevents huge swings in the measurement of a given variable, or prevents something from happening

mulch /məlCH/ noun/verb. - a layer of material used to protect and enhance soil quality and plant life

percolate /ˈpərkəˌlāt/ verb. - the movement of liquid through a porous medium


1. Gather your materials. You will need the following supplies:

mulch (see types on Step 3) · spreading tools (hands, wheelbarrow, pitchfork, shovel, trowel, etc.)

2. Watch the following YouTube video to see a demonstration of how to mulch a garden bed. Then, follow along with the remainder of the lesson by reading the steps below.

💧🌞🌡So, what does mulch do? … Mulch has a variety of functions, depending on the type of mulch used. Generally, mulch helps the soil retain valuable moisture at the surface, helps buffer temperature swings, dampens erosion from wind and water, and prevents sunlight from reaching weeds. Mulches derived from things that were once living can be mixed into the soil as organic matter, while still-living mulches can function as habitat for pollinators. Dark colored mulches will absorb more heat to keep the ground warm in a cold area, while light colored mulches can keep the soil cool by reflecting sunlight (and potentially increasing rates of photosynthesis!). Read on to find the right mulch for you!

3. Consider the type of mulch that will work best for your operation. Using multiple types of mulch may address diverse needs of the farm or garden, but may also make application and management more intensive. Use materials that are readily available, are cost effective, and address the widest range of needs for the operation.

  • Grass clippings: cheap if they are available or self-sourced; won’t compete for nutrients like living mulches; useful when used in tandem with something that can effectively mix with the grass clippings (for aeration); can cause cultivated plants to rot (dry grass is better for this reason)

  • Leaves (including pine needles): effective temperature and moisture regulation, and a decent source of organic matter; pine needles can help create acidic soil environments

  • Straw: provides good aeration, and is less likely to cause rot to cultivated plants than “green manure”; more porous than leaves and grass clippings; reflect light off of the ground; may contain weed seeds

  • Wood (bark, woodchips, sawdust): effective for warming cooler soil surfaces; can be effective for trees and shrubs up to the woody part of the plant, but should be kept away from plants with softer stem tissues

  • Live plants: typically fast growing plants that remain under the canopy of the main crop, like grasses and potentially legumes (which will fix nitrogen into the soil); cool the soil surface and may significantly reduce erosion; will suppress weeds, but may also compete for resources with cultivated plants

  • Plastic cover: cannot be mixed into the ground, but an effective weed barrier (prevents full photosynthetic capacity; can cover growing area very precisely, while absorbing or reflecting light (and therefore, heat) depending on the color

  • Newspaper: can be placed under many different mulches, making it a great supplemental material; can be sourced from home; suppresses weeds effectively; may be difficult to apply

4. After choosing the source of mulch, it is time to spread it on your garden bed. In order to spread a straw mulch (as we demonstrate in our video, linked above), use your hands (or some other tool -- see materials in step 1) to pick up a bunch of straw, and spread it over the top of newly planted seeds, and between established plants. To prevent pathogens from spreading to cultivated plants, straw shouldn’t necessarily be crowding the stem or touching the leaves of these plants (seedlings may still emerge through a mulch layer of straw, including weeds -- yikes!). Use enough straw to make a layer of about 3 to 6 inches. The amount of mulch used will help determine how quickly and how much water percolates down to the soil. Replace the mulch when it has been compacted or decreased in total volume (decomposed).

Additional Resources:

Download the PDF version of this lesson plan:

How to Mulch Your Garden
Download PDF • 506KB

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