Planting Vegetables After Brush Killer: Soil Residue Risks

Whether vegetables can safely follow brush killer application depends entirely on the specific herbicide used. Most lawn herbicides degrade within 6 months, but some persist for years.

Herbicide Persistence Categories

• Short-lived (most common): 2,4-D, dicamba, glyphosate — weeks to 6 months.
• Long-lived soil sterilants: Prometon, tebuthiuron (Spike), imazapyr — 1–3+ years.
• Problematic specialty chemicals: Clopyralid (often in lawn mixes) — persists in compost/mulch, damages tomatoes, beans, peas.

Practical Assessment

1. Identify the product if possible (check records, ask applicator).
2. Bioassay test: Plant sensitive seeds (beans, tomatoes) in pots with soil from the area. If they germinate and grow normally for 3–4 weeks, risk is low.
3. Observe weeds: If diverse weeds grow vigorously, residues are likely minimal.

When in Doubt

Wait a full growing season. Remove top 4–6 inches of soil and replace with clean topsoil if sterilants were used. For unknown applications, the bioassay is your best, lowest-cost safety check.