Mulching in the vegetable garden

By Melanie Mathieson
Gardening Guru

I’m a big advocate of mulches because if I didn’t use mulch, I could never keep up with the weeding duties. My trees, shrubs and perennial beds are mulched with bark (woodchips are a great alternative). But when it comes to the vegetable garden, there are more mulch types to try.
Over the years, I’ve mulched my vegetable garden in Fort Frances with straw, newspaper, grass clippings, carpet, leaves and black plastic. I was interested in trying different mulch types for different applications and the results were mixed over the years.
The straw worked great the first year because it was very old straw and the weed and oat seeds had died over time. The next year I had to use fresher straw and it contained many seeds and I had to weed out foot-high oat plants for most of the summer. Newspaper was okay but had to be secured down with boards and dirt and by the end of the summer it was already biodegrading so was not very effective at that point. One year I used shredded paper around the bases of my cucumbers and that worked really well as the white paper reflected the sun back onto the cucumber plants and produced a fantastic crop as well as kept weeds at bay. Grass clippings start to biodegrade very quickly and can get slimy depending on the weather and the amount of rain we get. I also tried mulching with leaves but like grass and newspaper they tend to state to biodegrade and by mid-summer they isn’t much left and unless you have a stockpile you cannot replenish the layer of leaves. One thing for sure, all of these organic mulches will eventually biodegrade and add nutrients to your soil so that is a positive.
Scrap carpet worked great for a couple of years as I laid them down in the pathways. It is bit messy and you have to take is out and dry it before storing for the winter so this is not for everyone as they just may not have the space. Obviously carpet is limited for use in the pathways. I tried black plastic in areas where I planted tomatoes, peppers, melons, squashes, pumpkins and cucumbers. Plastic mulch can yield some great results as the plastic keeps weeds at bay and helps to heat the soil below which all of the crops I listed thrive on. But be aware the plastic can prevent adequate moisture from reaching the crops so you must be diligent about making sure moisture conditions remain adequate. Other cons of installing plastic is that it is a chore to install and must be placed in the garden before you plant the crops, you have to cut holes into it before you plant your plants and depending on the size and thickness of your plastic you may not be able to reuse it the next year. This can create a lot of unnecessary garbage. Clear plastic can also work but black is better but is becoming harder to find. Another alternative for the tomato patch is red plastic that you can find in some garden supply stores and through mail order. Scientific research indicates that the reflection of light off of red plastic is favourable for growing better tomatoes. Some gardeners will use the black landscape fabric as an alternative to black plastic but it can be expensive and usually can only be used for one season.
Before you decide to use a mulch product in your garden it is best to do a bit of research first because you should be matching the mulch to the crop, weather conditions and soil. As mentioned above, some plants are heat-loving like peppers, tomatoes, eggplant, squashes and melons and are great candidates for plastic mulch but cool-weather crops such as peas, broccoli and lettuce don’t like the extra heat from a plastic mulch and are better off with straw, leaves or paper mulch. These mulches can lower soil temperatures by as much as 20 to 25 degrees, which may keep cool-weather plants producing right through the summer’s heat. Just remember it is okay to mix and match mulches in your garden if you want to try different types for different crops. If you want to only use one type aged straw (if you can find it) is your best bet for a general purpose mulch.
Listed below are some handy tips to keep in mind when considering mulch for your vegetable garden.
•Keep mulch at least an inch away from plant stems to avoid rot and fungus problems.
•Leave at least half your grass clippings on the lawn. They are an important source of nutrients.
•Clippings used as garden mulch should be sun-dried for a day or so. Do not use clippings from lawns treated with herbicides or toxic pest controls.
•Use only leaves that have been aged at least nine months. This allows the growth-inhibiting phenols to be leached out. Store the leaves from last fall in garbage bags in a shady dry spot. If they were dry when bagged they will take longer to decay and should be good for spring use in the garden.
•Secure plastic mulch with pins you make from bending pieces of thick wire approximately 6-8 inches long into a “U” shape. Cover the entire row before planting, and then cut planting holes as needed. You can also cut the plastic in half lengthwise, and snuggle it up near the plants from each side if you want to install it after crops are already established.
•Beneath the mulch, apply a fertilizer suitable for your crop. As organic mulch, especially leaves and straw, can rob the soil of nutrients especially nitrogen as it is decomposing.
Mulching the vegetable garden not only reduces your weeding chores but can also reward you a better harvest. Give it a try as it may become one of your best garden tips too.