Perennial weeds can be difficult to control. But waiting will only let the problem worsen.
Have just a few? When the soil is moist gently loosen the soil and gently pull from the bottom of the plant (yes, loosen and pull gently so you can get out as many roots as possible without breaking them off). Don’t be surprised if you have to “follow” the roots (loosening the soil along the way) while you pull - they can travel quite far! If the few perennial weeds you have are mixed in with other plants, you might try applying a nonselective herbicide when the weeds are actively growing. Paint it on with a brush so you do not kill the nearby plants with overspray. Repeat both methods as needed.
If you have a heavy weed problem and can do without the weedy area for the season, you could try solarization during the hot summer months. Water the area well. Cover the area with black plastic and secure the edges with soil, rocks, or earth staples (you can make them with wire hangers). Leave the plastic on for 60 days. The heat from the summer sun will sterilize the soil.
If you can leave the area fallow (with no garden plants) for the season AND would like to enrich your soil in the process, try smother cropping. This method basically starves out the weeds by planting another crop that shades out weeds combined with rapid harvest cycles that do not give the weeds time to replenish the food reserves in their roots. Here’s how:
- Cultivate the garden and heavily sow a series of fast growing cover crops. Here is one example of a smother crop series- others end with a legume to add nitrogen in the fall and you can use other crops as well. Remember to water if needed.
- Do now - sow OATS. When they start to head out, mow and till them into the soil. That should be sometime in mid summer.
- Right after the oats are tilled in, sow buckwheat. As soon as the buckwheat starts to flower mow and till it in - probably in early fall.
- Right after the oats are tilled in - sow rye. Leave that over the winter. Let it come up in the spring. Mow and till it in before it flowers or when you are ready to work your garden- whichever comes first.
NOTE: If your garden is overcome by aggressive perennial weeds like comfrey you may have to repeat the smother crop cycle next year. But at the end of it you will have weed free and very rich soil. You can take that to the bank!
You can find answers to many gardening questions at our consumer horticulture web site: http://consumerhorticulture.psu.edu/, or contact your local cooperative extension office. In Lackawanna County ask for the Garden Help line at 963-6842 or email LackawannaMG@psu.edu.
Terry Schettini, Extension Educator
Jim Kessler & Dorrie Mininger, Susquehanna County Master Gardeners
Penn State Cooperative Extension in Lackawanna County
Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce.
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