Avoiding growth regulators (PGR) and other residues

Growth regulators (English: plant growth regulator, PGR for short) are substances that artificially influence a plant's cell division, growth form, or flower formation — for example, to force particularly dense, heavy buds.

Some of these substances are suspected of being harmful to health and are not approved for growing consumption plants in the EU and Switzerland. The real problem: they sometimes appear undeclared in nutrient products advertised with unrealistic yield promises.

Buy nutrients only from established brands with a full ingredient list — if a product promises a 'secret formula' or 'guaranteed double yield' without disclosing the ingredients, caution is warranted.

If in doubt, a look at our nutrient catalog helps: it lists products with a known, traceable composition.

For all common nutrients (nitrogen, phosphorus, potassium, Cal-Mag & co.) you don't need any special products — the nutrient calculator in the tools is enough for a normal nutrient program.

Unusually hard, heavy buds, a chemical rather than plant-like smell, or buds that are much denser than typical for the described strain can — but don't have to — indicate a problematic product in the nutrient supply chain.

These signs are only a rough indicator. The only reliable check is a lab test (see "Reading a COA correctly"), which you usually don't need for hobby growing if you've used known nutrients from the start.