Greenpeace questioned megastores with garden centres about selling glyphosate-based Roundup. Dehner, Hagebau and Hellweg have not yet banned the weedkiller, though Hagebau and Hellweg are assessing whether to continue selling the product.
But the German Federal Institute for Risk Assessment (BfR) does not share this view.
In April, European Commission environment committee MEPs said glyphosate should not be approved for use in or close to public parks, public playgrounds, public gardens or home use. They recommended glyphosate re-registration for a further seven years.
The Standing Committee on Plants, Animals, Food and Feed (PAFF) will vote to adopt the Commission proposal (that glyphosate be relicensed) by qualified majority at their May 18-19 meeting.
Greenpeace said: "As long as the health risks of glyphosate are unclear, the precautionary principle should apply."
German retailers surveyed by Greenpeace:Bauhaus