Use Preen with care in a vegetable garden: Ask OSU Extension (2024)

Plain Dealer file

Always read the directions when using Preen in the vegetable garden.

I hate pulling weeds. Is it safe to use Preen in my vegetable garden?

Yes, Preen may be used in vegetable gardens, BUT it is very important to carefully read and follow all label instructions.

Preen contains an herbicide, trifluralin, which will only affect new seeds that are beginning to germinate. Specifically, this herbicide inhibits the growth of roots and shoots when it is absorbed by the roots of newly germinated weed seedlings. However, it doesn't affect any existing perennial weeds like dandelions, grasses or weeds that have already germinated. This is why the label states "first, remove all existing weeds."

The big question that comes to mind is: If it affects newly planted seeds, won't vegetable seeds be affected by this product? That can be a concern if this product is placed over the top of recently planted, small seeds, like carrots. Typically, large-seeded vegetable plants, like beans and peas, are not affected because the seeds are placed deeper in the soil and not up near the soil surface. Transplants are not usually affected because a root system is already developed and that root system is planted deep into the soil. Research has shown there is no significant absorption or translocation of trifluralin in crops grown in soils treated with trifluralin.

Garden checklist

• Buy a new metal file for sharpening all garden tools.

• Do not put gardening tools away with soil stuck on them. This will trap moisture against the metal, and it will begin to rust.

• Fill a bucket almost full of sand and add some used motor oil. Simply push the gardening tool into the oil/sand mix to both clean and lightly oil the tool.

• File a sharp edge on the hoe and get after those tiny weed seedlings.

• Add suggested amendments to the garden, using your soil-test recommendations, and then till them into the soil.

• Using a pencil and a garden map, plan out where each crop will be planted this year.

• Check out all of the garden hoses for any breaks or leaks.

• Make sure the rubber gasket is present and flexible in the female end of the hose.

• Now is the time to prune back overgrown and unruly forsythia.

• Cut a few heads of lilac blooms and bring them into the house to make the inside smell like the garden outside.

The principle of any pre-emergent herbicide is to create a weed-control barrier in the top layer of soil, preventing weed seeds from germinating. To be effective, these products must be activated either by watering or shallow incorporation into the soil. It does not move much in the soil but absorbs tightly onto clay particles and remains where it is placed at application. Once the barrier is created, any disturbance of soil in that area, by any hoeing or cultivation, provides an opening for those weeds to grow.

Contrary to popular opinion, herbicides do not stay in the soil indefinitely. And in fact, these products are broken down by soil microorganisms, which use them as a food source. For this reason, in order to have a season-long, weed-free vegetable or flower bed, it requires a reapplication of Preen in about 9-12 weeks.

Announcements

The Master Gardeners of Cuyahoga County and Ohio State University Extension are sponsoring Plants in the Park. This annual plant sale will be from 10 a.m.-3 p.m. Saturday, June 6, at the Kiwanis Pavilion, Independence. Master gardeners will be there for an information session about container gardening, and to answer questions and to discuss how to select the best plants for your garden. There will be perennials, vegetable, herbs and container plants for sale. With the purchase of four plants, buyers will receive one plant of equal or lesser value. This event is free. Check here for more information.

Draper is an extension educator, Geauga County OSU Extension office. Call a master gardener for advice 10 a.m.-1 p.m. Mondays and Thursdays at 216-429-8235. Gardening information is also available at cuyahoga.osu.edu and webgarden.osu.edu. Write master gardeners at mgdiagnostics_cuya@ag.osu.edu.