News release: Mulch in your Vegetable Garden

Tim Baker, MU Extension Horticulture Specialist
102 N. Main, Suite 1, Gallatin, MO 64640
660-663-3232, bakert@missouri.edu

Release Date: May 29, 2014

Headline: Mulch in your Vegetable Garden

Sometimes I get questions from vegetable gardeners about what herbicide they can use in their gardens. I usually try to steer them another direction.

That’s not because there are not herbicides labeled for vegetables.  There are.  But often they are only available to growers with pesticide applicator’s licenses. And even if they were available to homeowners, using them on a small scale in a vegetable garden could invite disaster. An herbicide that might work for one vegetable might not be labeled for another.  It might even cause injury to some plants.

Really, on a small scale, I think mulch is the best solution.  Mulch not only keeps down weeds, but it also conserves moisture and either warms or cools the soil.  That’s all good, but you need to know how to use mulch properly.

What can be used for mulch?  Almost any organic material can be used. Compost, straw, lawn clippings, even waste paper products are good candidates. Remember that some of the materials may bring additional weed seeds to your garden, so be careful. Some synthetic materials can work as well, such as the black plastic mulch that commercial growers use.

So is there a right way and a wrong way to use mulch?  Yes, there is.  Mulch can either work for you or against you in the garden.

Think about early spring, when temperatures are cool.  That’s the time to bring out the black plastic mulch.  Black plastic not only keeps down the weeds, but it warms the soil. That’s what you want this time of the year, to get your plants off to a quicker start.

If used on a raised bed, black plastic also acts as an umbrella, in periods of excessive rains. That will also help your plants.  Remember, however, that dry weather will come, so it’s always a good idea to have some drip tape underneath the mulch to irrigate with.

If you used an organic mulch in the early spring, it would insulate and keep the soil cool.  This isn’t generally what you want this time of the year.

So what happens when warm weather arrives?  The goal here is to keep the root zone cool. If you started out with black plastic mulch, simply paint it with whitewash or put an organic mulch on top to keep the sun from hitting the black plastic. That will keep things cooler. If the plants have covered over the black plastic on their own, you can skip this step. 

If you started out with bare soil, and have kept a sharp hoe after your weeds, hot weather is the time to bring out the organic mulches.  That will keep things cooler and conserve moisture.

Be sure not to pile on the mulch too heavily. Certain types of materials tend to mat together and repel water.

If you would like further information, call your local MU Extension Center and ask for our guide sheet on mulches.