Controlling garden weeds

Published 5:00 pm Friday, March 30, 2018

As soil temperatures warm up and gardeners begin to plant their transplants and seed, the issue of how to control weeds often arises. A weed is a plant out of place, so how do we control weeds in our garden?

The problem with vegetable gardens and controlling weeds is that we grow plants in small spaces that have different plant characteristics. You can divide plants into two main categories — grasses and broadleaves. Grasses have parallel veins, and broadleaves are palmately veined — that is the veins radiate from the stem to the tips of the leaves.

Herbicides generally control one or the other. Using a pre-emergent herbicide usually doesn’t work in a small garden if you grow corn, a grass and green beans, a broadleaf. If you have large areas to plant and you flag off the areas it might work. You must read the label very carefully. Identifying the weed is the first step in selecting herbicides.

If you use a non-selective herbicide such as Roundup, if both the plants and weeds are up at the same time you run the risk of spraying both and killing the vegetables. Even if you are careful, spray drift may cause damage as well.

Tilling the soil is the most common method of controlling garden weeds. It uproots the weeds and dries out the roots. It also brings up buried weed seed and places it in an environment where it may germinate. Weed seeds can stay dormant for many years in the soil. This is why after each deep cultivation, a flush of weeds appear. They are usually all the same height. Weeds are much easier to control when they are small and in the “white root” stage. When they are uprooted at this stage the ground heat will whither the “white root.” If you have to pull weeds with both hands, you’ve waited too long.

Controlling weeds in the top two inches of the soil is the best bet. If the weed seed is exhausted in the top two inches, weed control is much easier. You may have to pull the occasional escapee. If you deep till, the process will have to start all over again.

The usual method of controlling weeds after the vegetables are up and growing is using a hoe. The most common hoe is a paddle hoe with a gooseneck for better alignment for the six by four inch blade. Never dig deep with a hoe. They are designed for shallow cultivation. A fiberglass-handled hoe will last for many years but a wooden handled hoe that is oiled and kept out of the sun will last a long time as well.

Another option is using mulch to control weeds. Placing mulch or compost around the plants will suppress weeds, conserve soil moisture and add organic matter. Do not use fresh woodchips or sawdust because they will draw the nutrients away from the vegetables. Manufactured products such as the mulch plastics and paper products will warm the soils and suppress weeds. Many of our large-scale vegetable farms utilize plastic mulch on raised beds. Old newspapers work well if wetted and rocks or bricks are placed on them to prevent them from blowing into a neighbors yard. The purpose of the mulch is to deny weeds sun and to act as a barrier to growth.

Another way is to plant a winter cover crop such as Yuchi clover, crimson clover and/or winter rye. These plants form a natural mulch when mowed in the spring. If you cultivate just where you plant your vegetables this system will provide weed control into July. Rye also has an allelopathic effect which suppresses weeds.

Remember that killing the weeds in the top two inches of the soil is the best solution for weed suppression.