Managing Weeds Before Planting

Here are some options for managing weeds before planting species that support beneficial insects. 
  • Kill weeds without disturbing soil 
  • Cover crop – buckwheat 
  • Soil solarization 
  • Weed seed bank depletion 

Kill weeds without disturbing soil

Starve the weeds of light by covering them with cardboard or a heavy tarp for three to four weeks (six or more weeks if killing sod); more info can be found in Tarping in the Northeast. Alternatively, you could apply an herbicide appropriate for your setting. 

Notes on killing weeds without disturbing soil

  • Use this approach before transplanting your desired species 
  • It may be more difficult to establish desired plants from seed if you can’t create a nice seedbed with tillage 
  • If using an herbicide, select one that is registered in your state and allowed for use in your setting. Always read and follow all pesticide labels, including those on herbicides. 

Cover crop – buckwheat 

  1. Till the soil. Choose the tillage tool – from a shovel and rake to equipment pulled by a tractor – depending on the area you will plant. Be sure to create a high-quality seedbed, avoiding large soil clumps. Depending on your site, you may need to remove existing vegetation first. 
  2. Plant buckwheat seed (70 lb/A if broadcasting, less if planting using a seed drill) into freshly-worked soil. In Central NY, this should happen around late May (soil temps > 65°C). Spread seed evenly over the ground. Gently rake it in, not too deeply, and stomp or roll the area to press seeds into the soil. 
  3. Mow, or find another method of killing buckwheat when it is in full bloom. About five weeks after planting, start checking the buckwheat. It is ready to mow when there are no flower buds and all flowers are open. Mowing too soon will result in the plants re-growing and re-blooming. If you wait too long, the buckwheat will produce seed and can become a weed. 
  4. Plant a second crop of buckwheat by repeating steps one through three. 
  5. Plant desired species as soon after mowing the second buckwheat crop as possible. 

Notes on using cover crops to manage weeds

  • Feeds beneficial insects and builds soil health while managing weeds 
  • Use prior to either direct-seeding or transplanting desired species 
  • Best if you want to transplant or seed desired species in late August or early September 
  • Other cover crops can be used (see Cover Crop Guide for NY Growers), and will be better choices if you don’t want to plant until mid-September or later 
  • Buckwheat can become a weed if it is allowed to go to seed

Soil solarization 

  1. Till the soil. A variety of tools can be used—from a shovel and rake to equipment pulled by a tractor—depending on the area you will plant. Depending on your site, you may need to remove existing vegetation first. Be sure to create a high-quality seedbed, avoiding large soil clumps. This will help to ensure that less air is trapped between the plastic and the soil, improving heat transfer. 
  2. Solarization works best when you start with moist soil because water conducts heat better than air. If the soil is bone dry, irrigate or wait for rain. 
  3. Lay the clear plastic. Cut a sheet of 6-mil clear, UV-stabilized plastic with an extra 12-18” on all four sides. Dig a trench around the edge of the plot to be solarized. Stretch the plastic somewhat tightly over the soil. You don’t want it to billow on a windy day, but you don’t want it to be stretched so tight that it rips. Bury the edges of the plastic 4-6” deep around the entire perimeter of the plot. Stomp the soil down over the edges to create a tight seal.  
  4. Leave the plastic on for the entire summer. If small holes or tears appear in the plastic, seal them with clear packing tape to keep in the heat. 
  5. Just before you are ready to plant in the fall, remove the plastic. Cut off any weeds that managed to grow at the soil line. Minimize soil disturbance, as this can bring up more weed seeds from below the upper layer of solarized soil. 

Notes about solarization

  • Best for smaller areas and very sunny spots 
  • Will not kill heat-loving weeds like purselane 
  • UV-stable clear plastic may be expensive; consider using leftover pieces from a high tunnel. Clear plastic that is not UV stable might not last all summer, depending on your location and characteristics of the plastic 

Weed seed bank depletion 

  1. Till the soil. A variety of tools can be used—from a shovel and rake to equipment pulled by a tractor—depending on the area you will plant. Depending on your site, you may need to remove existing vegetation first. 
  2. Allow weeds to grow at least 3” tall (but not to produce seed). 
  3. Kill the weeds by tilling the soil or applying an appropriate herbicide. If using an herbicide, make sure you read and follow the label and wait until weeds are dead before proceeding. 
  4. Repeat steps one through three until you are ready to plant your desired species or the end of the growing season if you will not plant until the following year. 

Weed seed bank depletion considerations

  • Works in large or small areas 
  • Use prior to direct-seeding or transplanting desired plant species 
  • Requires careful timing of tillage or herbicide application before weeds make seeds 
  • If using an herbicide, select one that is registered in your state and allowed for use in your setting. Always read and follow all pesticide labels (including herbicides). 

This guide was prepared by Amara Dunn-Silver. Last updated on 3/17/2023.

Funds were provided by:

  • The Towards Sustainability Foundation
  • USDA National Institute of Food and Agriculture, Smith Lever project 2020-21-108
  • NYS Department of Agriculture and Markets
  • NYS Department of Environmental Conservation