How to Use Mulch in the Vegetable Garden
If you read the post on the benefits of mulching in the vegetable garden and are convinced that you want to start mulching, your next concern might be how to use mulch in the vegetable garden. It can’t be as easy as just spreading it around the plants, can it? Well, there are a few things you will want to consider before you begin mulching in your vegetable garden. Although inorganic mulch is beneficial, I find that organic mulch provides all the benefits while providing nutrients and improving the structure of the soil as it decomposes.
What is Organic Mulch?
Organic mulches are biodegradable. When you use them in your garden, they will decompose over time. This decomposition process will return nutrients to the soil and also improve the structure of your soil. An bonus is they will invite earth worms and other beneficial insects to enrich your soil.
I believe that mulch is aesthetically more pleasing because your garden looks tidier and weeds are diminished. It also adds a critical thermal layer of protection for the soil and roots during extreme weather. If you have a plant that is borderline for your zone, the extra protection in the winter can help ensure that it survives a particularly cold period. In heat extremes, quite simply, mulch can make the difference between surviving, thriving and dying.
There are a variety of types of organic mulches:
Wood Chips as Mulch
Fresh wood chips are often available at local landfills and can sometimes be dropped off by the truckload if you know the local company that clears roads and highways in the summers. A common misconception is that fresh wood chips are bad for mulching because they tie up nitrogen during their decomposition. But, since the material will only be used on the surface of the soil and not mixed in with the soil, they will not pull nitrogen from the soil. While some say that it is best to use wood chips for shrubs and trees, I have mulched many a vegetable garden with wood chips and found them to be successful. If you are concerned about using fresh wood chips, then you can let them age before using in the vegetable garden.
Wood chips from tree services are usually a combination of bark, sapwood, hardwood and leaves so as they break down, they provide small amounts of nutrients to the soil slowly. As an added benefit, they increase the organic matter of the soil as they break down. Through the years, the organic matter works down into the soil with the activity of earthworms and insects that live and burrow through the soil. This added organic matter in the soil produces healthier plant growth.
Ideally wood chips should be applied at a depth of 4 to 6 inches. They will settle after a few weeks and like any organic mulch, need to be replenished periodically to keep providing benefits.
Shredded hardwood bark is a popular and inexpensive mulch. As a derivative of the lumber and paper industries, it is a great way to recycle. As it decomposes, this mulch helps increase soil fertility. It can come in a variety of sizes from large nuggets to smaller shreds. I think it is one of the most attractive mulches – it looks great around trees, shrubs and perennials.
If you get shredded bark that is dyes, check to ensure the dye is vegetable based and acceptable for organic gardening, if that is your goal.
Sawdust is readily available from sawmills so it can be inexpensive to acquire. This mulch is acidic, so it would be a good mulch for acid-loving plants such as rhododendrons and blueberries. A mere 2-inch layer of sawdust will provide good weed control. Fresh sawdust contains very little nitrogen, however, and its breakdown pulls nitrogen from the soil – so use sparingly or add extra nitrogen to the sawdust when used for mulch. To add extra nitrogen to the sawdust, mix one pound of actual nitrogen to 50 pounds of dry sawdust, to cover about a 100 square foot area in your garden. If you are using ammonium nitrate (33-0-0), add about five pounds. For ammonium sulfate (21-0-0), add about three pounds to the sawdust. If you want to use organic fertilizer, add seven pounds of blood meal.
Lay the sawdust mulch out to a depth of about 1 to 1 ½ inches being careful not to pile it up near the trunk of trees and shrubs or the stem of the plant to avoid rot. A 1/4 inch layer of sawdust can be helpful in starting seeds since it will help to keep moisture in. One disadvantage of sawdust is that it can form a crust that makes it difficult for water to soak through. Another disadvantage is that it decomposes quickly thus compacting upon itself. If you use sawdust in the garden, you will likely have to replenish it and re-fluff each year.
Grass Clippings for Mulch
They cool the root zone, conserve moisture and add massive amounts of nitrogen back to the soil. They allow you to use the refuse from mowing the yard. They can be used either fresh or dried. Use a layer only about 1/4 inch thick layer if using fresh grass so that the clippings can break down before they begin to rot. Dried clippings can go on thicker. The dried clippings also make great side dresses for vegetables. Late fall and early spring are great times to add grass clippings to the garden, mixing them into the soil at least eight inches.
Leaves as Mulch
Leaves are great as mulch and are of great nutritional benefit to the soil. Dried leaves actually contain about 80% of the original plant nutrients including carbon, potassium, and phosphorus. They also feed the earthworms and beneficial microbes. When added to your garden, leaves feed earthworms and beneficial microbes. If you go look at the soil in a forest that has decomposed leaves from years past, you will find soil that is light and rich. In addition, they can make a great looking mulch in the flower garden and they provide great insulation from the cold.
Because leaves can matt up and stick together when they get wet, it is important to shred as many of them as you can. If you don’t have a leaf shredder, you can pile them up on the lawn and run over them a few times with a lawn mower. Over time, shredded leaves become leaf mold which is a fantastic mulch that enhances the soil tremendously. For a wonderful enhancement to your garden, don’t burn your leaves this year – instead shred them and use them as a fantastic mulch.
Using Newspapers as Mulch
Newspaper is extremely helpful during cold weather for keeping your plants safe and warm. And it’s also an effective way of for keeping weeds out of your beds. Layer the sheets, overlapping the edges so they don’t separate. You can use anywhere from 2 to 20 sheets of newspaper, depending on your purpose for the mulch. Five to 10 sheets are good for weed control and 10-20 sheets for protecting the plants from the cold. Another option is to shred the newspapers, tearing by hand or even using a paper shredder. In some parts of the country, shredded newspaper in bales is available. Your local Recycling Center or Solid Waster Management facility will have information on this if available in your area.
Newspaper can be used alone, but covering it with straw or another mulch will make it last longer. The newspaper is more environmentally sound method to control weeds than traditional black plastic.
How to Apply Mulch
There are some things to keep in mind when applying mulch. The biggest thing people do wrong is not applying enough mulch. At least two to three inches are needed to smother weeds and retain soil moisture. If less than two inches of mulch is applied, light will go through allowing weed seeds to germinate.
Another important part of applying mulch is ensuring that it is not pushed up against the plants. Make sure mulch is pulled back at least an inch from tree trunks, shrubs and the crowns of your vegetables, annuals and perennials. Mulch applied up to the plant stem or trunk can hold moisture thus causing the plant to rot.
Organic mulches decompose, so they need to be replenished every year. In especially harsh summer weather, the mulch may need to be replenished in the spring and in the fall. Mulch can benefit all areas of your garden and make your gardening easier and more productive. When you mulch, it mimics the natural processes of a forest, where each year leaves fall to the ground, decaying, then recycling in the soil to provide nutrients and protection to the plants above. As an bonus, the more that you are able to use materials from your own garden as mulch, the more sustainable it becomes. And, your plants and soil will love you for providing a better environment for them.