Organic and Inorganic Mulch Types
Whether you are planting a vegetable garden, fruit trees, or ornamentals like flowers and shrubs, mulching your beds will save you water and work, and will make your plantings look more tidy and professional. Depending on what you are growing, there are many choices for mulch, both organic and inorganic.
The most popular times to mulch gardens is in the spring or fall, but mulch can be added at any time of the year. For vegetable gardens, wait to mulch until after the soil has warmed, unless you are growing plants that prefer cooler soils, such as potatoes, lettuce, or spinach.
Grow a Healthy Garden!
Mulch has many advantages:
- Mulch beds stay cooler in the summer and warmer in the winter.
- Mulched beds prevent the soil from cracking and erosion.
- Mulch discourages weed seeds from germinating and perennial weeds from getting the sunlight necessary for growth.
- Mulch is aesthetically pleasing, and makes the garden look neat and well tended, and makes weeding easier.
Organic mulches benefit the garden in many ways:
- As they break down, organic mulches add nutrients to the soil and improve soil texture. Improved soil texture helps soil to retain moisture and to drain properly.
- Mulched beds are more attractive to earthworms and beneficial microorganisms, which further improve soil texture and fertility.
- Mulched beds need watered less often.
Depending on the area where you live, there may be bulk mulches available to be delivered. In the spring and sometimes in the fall, your local nursery will have a selection of mulches available in bags or in bulk.
- Pine bark is aesthetically pleasing, and is usually a by-product of sawmills. Pine bark can wash away in heavy rains and will break down in a few years.
- Pine needles are readily available in some areas. Pine needles tend to weave themselves together to resist being washed away in the rain. Pine needles are also acidic, so will lower the pH of your soil. If you are growing acid-loving plants, like azaleas or blueberries, then pine needles will help to keep the pH of your soil low.
- Wood chips make a good mulch, but will wash away during heavy rains. Fresh wood chips should be aged for at least one year to allow acids, which will be detrimental to plants, leach out.
- Cypress mulch is popular, but expensive. It is not sustainable since it is usually clear cut from cypress swamps.
- Leaves are an excellent mulch as long as they have been shredded into small pieces by a leaf mulcher. Unshredded leaves tend to compact, which sheds water away from the garden. Trees have deep roots, and reach minerals that are not available to shallower rooted plants. Many minerals are present in leaves which are beneficial to plants.
- Grass clippings are a good temporary informal mulch if the grass has been grown organically. Clippings should be dry before they are added to the garden.
- Hay is baled from green plants and grasses after drying in the field and is fed to livestock during the winter. It makes an excellent, fast decomposing mulch for informal areas and gardens, but may contain weed seeds. If it is available, hay that is too old to feed to animals and has been outside makes a good mulch. Many of the weed seeds will have germinated and died, and some farmers or ranchers will sell it for much cheaper than fresh hay. A very thick layer of hay mulch or straw mulch is likely to discourage weed seeds as well as perennial weeds such as dandelions that come back from their roots.
- Straw is baled from the chaff of crop plants such as wheat and oats. Like hay, it contains weed seeds, but it is more aesthetically pleasing in informal settings such as vegetable gardens and paths. Some organic gardeners find that straw reduces the Colorado potato beetle populations in potato patches.
Interested in Vermiculture?
Inorganic mulches do not break down to improve the quality of soil, but they do have advantages:
- For nightshade plants, red plastic mulch has shown in studies to increase the production of tomatoes and sweet or hot peppers.
- Black plastic mulch is useful to warm the soil in the spring and keep it warm longer in the fall.
- Woven cloth lasts for several years to keep weeds out of the garden while letting air and water through.
- Crushed stones, river rock, and pebbles are aesthetically pleasing, but a thick layer is needed to prevent weeds.
- Some landscapers use landscape fabric, or geotextile, underneath stones or other mulch, but after a few years, enough soil has blown in and formed on top of the landscape fabric to render them useless as a weed barrier but nearly impossible to remove without damaging plants.