Your concern about toxins in plastic planter boxes is very valid for any gardener growing edible plants. The direct answer is: it depends entirely on the type of plastic used. Not all plastics are created equal for food-safe gardening.
For urban gardening, the safest choice is planters made from High-Density Polyethylene (HDPE, labeled #2) or Polypropylene (PP, labeled #5). These plastics are widely considered food-grade, non-leaching, and are commonly used for food storage containers, yogurt tubs, and drink bottles. They are durable, UV-resistant (if specified), and do not typically release harmful chemicals into the soil.
Plastics to Avoid: Be cautious of planters made from recycled or unknown plastic sources, which may contain contaminants. Avoid old containers that held non-food chemicals. Also, while PVC (#3) is sometimes used, it can contain additives like phthalates that are best avoided for food crops.
Best Practices for Safe Gardening:
1. Check the Label: Look for planters explicitly marketed as "food-safe," "food-grade," or "safe for edible gardens."
2. Use a Barrier: If unsure, add a thick, food-safe plastic liner (like HDPE) to create a barrier between the soil and the planter.
3. Ensure Proper Drainage: Always use planters with adequate drainage holes to prevent waterlogging and chemical buildup.
4. Focus on Soil Quality: Using fresh, high-quality organic potting soil in a clean container is your best defense.
In summary, by selecting planters made from known food-safe resins like HDPE or PP and following simple precautions, you can confidently use plastic urban planters for your herbs, vegetables, and fruits without worrying about toxin contamination.