The weather has finally turned nice and many gardeners have been out planting vegetables. Unfortunately, radish, lettuce and broccoli plants are not the only things growing. This time of year, many weed seeds are starting to germinate and grow as well. Though mulches and hoeing are usually all that is needed for small vegetable gardens, homeowners with large areas may need the help of herbicides to keep ahead of the weeds.

Here are a few tips to help keep garden weeds under control this year:

There are two pre-emergent and one post-emergent herbicides that can be used in home vegetable gardens. Pre-emergent herbicides kill weed seeds as they germinate. They must be applied either before weeds come up in the spring or after weeds have been physically removed to prevent new ones from starting. Post-emergent herbicides are used to control weeds that are already actively growing.

The two pre-emergent herbicides are trifluralin and DCPA. Trifluralin is sold under the trade names of Treflan, Preen, Miracle-Gro Garden Weed Preventer’ and Monterey Vegetable and Ornamental Weeder. DCPA’s common name is Dacthal and is sold as Gordon’s Garden Weed Preventer Granules. Apply these products after the garden has been planted and plants are actively growing. For best results, they should be watered in. Check the label because they can not be used on all vegetable crops. For example, several of them can only be used on snap beans, onions, cabbage, cauliflower, broccoli, sweet potatoes and tomatoes. Many of these products will give some control for grassy and broad-leaf weeds.

The most common post-emergence herbicide is sethoxydim. It can be used to kill grassy weeds such as crabgrass, foxtail and goosegrass. It does not work on broad-leaved weeds. However, it can be sprayed directly over the top of many vegetables and not harm them. Sethoxydim is sold as Poast, Monterey Grass Getter and Hi-Yield Grass Killer. Unlike the pre-emergent herbicides, do not water after application because you will wash off the chemical. Finally, pay attention to “days to harvest” for the last spraying. For example, Poast can not be applied later than 30 days before harvest for leaf lettuce. Asparagus is just one day.

Make sure to read and follow all label directions. In the homeowner line of chemicals, products with the same active ingredients can be used on slightly different crops. Check the label to make sure the crop you are spraying is listed.