A ban on slug killer metaldehyde comes into force from 1 April as a result of Garden Organic's campaign.
The pellets cause significant harm to wildlife and a ban was originally announced in 2019, but was overturned due to a procedural error.
Defra banned outdoor use of the pesticide in September 2020 following advice about the risks that the product poses to birds and mammals.
No further supply was permitted from 31 March 2021, but distributors could sell stocks.
From 1 April 2022 it will be illegal to sell and use metaldehyde products.
Fiona Taylor, chief executive at Garden Organic, told HortWeek: "We are relieved that the ban on the use of metaldehyde has finally come into force. Changing habits can be challenging but enforced actions like this are essential to protect wildlife and support biodiversity.
“As gardeners, we know how devastating slug and snail damage to our food and flowers can be, but we also know they are an important part of the natural ecosystem. Using toxins to wipe them out is not only heavy-handed, worse than that, metaldehyde is a killer of birds and mammals and has horrible environmental side effects."
Organic slug pellets, which contain ferric phosphate, are effective against slugs and aren't harmful to wildlife. Biological controls are also an option. But the RHS announced recently it would no longer be classing slugs and snails as pests, as they are important for clearing dead matter from the garden and are key food for other garden animals.
How to dispose of metaldehyde
How you dispose of the pesticide, if you still have some at home, will vary according to where you live and your local council. Check their household waste and recycling information before disposing of any metaldehyde you have.