After discarding all the others anti snail remedies you can use environmentally friendly granules. Actually you can do it even earlier, but my opinion is that the snails and the slugs should be removed rather than killed because they too perform a useful function in some way.
If there was the right natural balance in the garden and in the garden, there would be no need for anti snail granulate nor of other remedies. But since hedgehogs, toads, shrews, moles, lizards and little worms have become increasingly rare (and we often chase them away too), some remedy should also be used to save zucchini and company.
The granulate anti snails we are talking about does not damage the ecosystem and is harmless to all domestic and non-domestic animals, including earthworms. It only disturbs snails and slugs, first attracting them and then satiating them so that they can retreat to their hiding places unaware of having had their last meal.
The formulation is called Ferramol, it is a natural compound based on ferric phosphate, and it has been on the Italian market for not many years. Today it is available in the products of some well-known brands and is a anti snails allowed in organic farming because it leaves no traces in the soil when it breaks down.
An important feature of Ferramol is that the granules are resistant to water and action anti snails it continues even with the rain, that is when snails and slugs celebrate. The compound first attracts gastropods in an irresistible way and then, after being absorbed, causes them to stop eating. Snails and slugs they just have time to reach the lair before they die.
I remain of the idea that first everything possible must be done to remove snails and slugs with mechanical systems and natural remedies, but I realize that there is a limit to everything. The anti snail granulate bio is all in all an excellent compromise between the natural balance of the soil and the need to preserve the harvest. To disagree are only the snails.
Organic anti snail granulate 1 kg
Organic anti snail granulate 500 gr