Glyphosate is a broad-spectrum systemic herbicide used to kill existing vegetation prior to planting new plants or sowing seed. Sold under brand names like Roundup, this popular weedkiller is non-selective, meaning it will destroy any type of plant it comes in contact with. Knowing how long you must wait to plant after glyphosate application is key.
What is Glyphosate and How Does it Work?
Glyphosate is absorbed through plant foliage and translocated down to the roots. It inhibits protein synthesis in plants, effectively starving them. Visible symptoms occur slowly over several days or weeks. It has no residual activity in soil. Glyphosate kills annual and perennial weeds, grasses, vines, trees, and shrubs right down to the root system when applied correctly. This allows for preparing planting beds from scratch by eliminating existing vegetation.
While glyphosate is considered safe when used properly, it is necessary to know proper waiting time before planting in an area where this herbicide has been applied.
Factors that Influence Wait Times
Several variables affect how soon you can plant after using glyphosate:
Method of Application
Foliar spraying is quicker acting than stump application.
Higher concentration mixes work faster than dilute solutions.
Thorough, uniform coverage is critical.
Type of Vegetation
Annual weeds die more quickly than established perennials and shrubs.
Woody brush and tree stumps decay at a slower rate.
Weather Conditions
Warm, sunny weather speeds the breakdown process.
Cool, cloudy conditions slow the glyphosate activity.
Your Tolerance for Regrowth
If unable to accept any regrowth, wait longer.
If able to hand pull a few weeds, can plant earlier.
General Guidelines Based on Application Method
Follow these general rules of thumb based on how you apply glyphosate:
Spot Spraying Weeds or Vegetation
Wait at least 1-2 days before planting. Annual weeds begin yellowing and withering almost immediately so planting can happen quickly in these areas. Watch for any regrowth.
Large Area Spraying for Renovation
Wait at least 7 days before direct seeding or planting through the dead vegetation. Wait 2 weeks before tilling or disturbing the soil. Some hardy weeds may resprout so monitor closely.
Stump and Brush Treatment
Wait 6-8 weeks before planting around stumps. The translocated glyphosate takes much longer to kill established woody vegetation and roots. Delay any soil excavation. Monitor for resprouts.
Inactive Ingredients
Some glyphosate products contain diquat or imazapic which linger longer in soil. Read labels carefully and extend wait times up to 2-3 weeks to be safe if using these mixes.
It’s important to note that glyphosate works by being absorbed through the foliage of the targeted plants. It then travels down to the roots, effectively killing the entire plant. Once the herbicide has dried on the leaves and has been absorbed into the plant’s system, it is less likely to pose a threat to future plantings.
Confirm the Vegetation is Dead
The most foolproof way to determine the appropriate glyphosate wait time for your situation is to watch the treated vegetation closely:
- All leaves and stems should turn completely brown or black.
- No new green growth should emerge for at least 2 weeks.
- Plants should not recover if you scrape outer bark or cut into stems.
- Woody brush should not resprout from roots or stumps.
Conclusion
Seeing is believing when it comes to confirming the glyphosate has fully translocated throughout the target vegetation. Waiting until all treated plants are clearly dead means your planting areas are safe for new vegetation. Always refer to the product label for specific instructions and follow proper dilution techniques. With glyphosate, patience pays off!