Do the new ferrous phosphate organic slug pellets work as well as the old metaldehyde slug pellets? This question was posed by a reader who felt the new slug pellets were ineffective.
Slugs infesting a vegetable garden. 3 on a lettuce!
Banning Metaldehyde Slug Pellets
The government moved to ban metaldehyde pellets that have been a gardener’s staple for as long as I have been alive. The ban was overturned on technical grounds but it remains a possibility.
There is supposed to be a danger that the poisoned slugs and snails would be eaten by wild life and poison the wild life in turn. Although the risk is there in theory there is little evidence for it in reality.
The main reason behind a ban was farmers using metaldehyde based slug pellets near water courses causing pollution problems. Remember, gardeners use a handful but farmers use hundreds of kilos.
Ferrous Phosphate Slug Pellets
The alternative slug pellet are thosed based on ferrous phosphate. Ferrous phosphate pellets are organically approved and, in the UK & EU, further treated with a bittering agent to dissuade pets from eating them.
There’s no evidence of risk to wild animals or pets from pellets or corpses except for some vet reports in the USA about dogs eating large quantities of pellets falling ill.
Eventually uneaten pellets degrade and become nutrients for the plants. Incidentally, I think they last longer in showery weather than the metaldehyde pellets.
Different Actions
When a slug or snail eats a metaldehyde pellet they produce a lot of slime which they leave behind them as they slither off and die. It’s very easy to see how many have been killed.
With ferrous phosphate slug pellets the action is different. The slug loses the desire to eat and goes off to wherever it hides in the day and dies out of sight. It’s not at all obvious to the gardener that they’ve been effective.
The Slug Pellets Disappear
If you scatter them as directed, i.e. thinly, and they’ve vanished over a night or two it means they’ve been eaten by the slugs & snails. Re-apply and you’ll get their surviving pals. The pellets actually attract the slugs so don’t over-apply as it can be counter-productive.
Summing Up
To sum up; I think ferrous phosphate slug pellets are probably slightly more effective than metaldehyde slug pellets. They are also arguably safer and definitely greener. On the negative side, they are slightly more expensive but there’s not a lot in it.
More Information on Organic Slug Pellets
I resorted to these in raised beds with netting on as hundreds of slugs were getting in. I grew my brassicas from seed and to see them being decimated angered me, so reluctantly after trying sheep wool collars and beer traps,my husband brought these home. I used them and find they do work.
I sprinkled them amongst the cabbage, broccoli, cauliflowers and beetroot. I have also put them around mt courgettes after the sheep fleece failed. I have harvested my first 5 heads of broccoli and beetroot which was eaten by micelast year!
However I planted spinach between 2 rows of carrots and the slugs crawled up the foliage of carrots and over onto the spinach.As they came over my raised beds and straight onto the wet leaves of the carrots they didnt come into contact with the pellets so thats why they failed. Otherwise I have used them in my pots of zinnias and in amongst the hostas in case the copper tape evades any as last year they looked like lace leaf plants! This year with sheep fleece, copper tape and pellets, we’re doing beautifully well!
I have tried everything and have failed to stop the nightly munching of my veg patch by slugs. This year 2024 they have destroyed my strawberries, leeks,and peas. Going to switch to pots.
I’ve found these new so called organic slug pellets to be utterly useless, slugs seem to actually enjoy them.
Surprised at your not finding the ferrous phosphate pellets effective. I’ve used them for years and they’ve worked for me. Farmers use them and if they didn’t work the farming press would have been swamped with moans! The farmers preferred the old pellets because they were cheaper – big factor when you buy tonnes.
The old meta pellets used to cause the slugs to leave obvious thick trails as they went off to die but the FP pellets don’t. The slugs tend to go underground to die.
I have found that they are pretty useless. I have a 4″ high wooden home made box with small pak choi about 2″ high. The box is on top of a wheelie bin near my greenhouse and there is no overhanging vegetation. I found they were being eaten completely leaving a 1cm stalk. I removed the eaten ones and sprinkled some ferrous phohate pellets around them all, they are still being eaten by slugs!
As regards the environment I don’t understand how phosphate pellets are better for farmers when used near water courses as they are a pollutant that cause of algal blooms and deoxygenation.
Hi SteveB – I suspect you’ve slug eggs hatching or slugs in your growing medium and they’re coming up to eat the pak choi. If the slug is nearer to the plant than the pellet it’s going to eat the plant. That’s my guess anyway.
As for the environment, farm slug pellets are applied by machinery at the optimum level so I find it surprising when you say the FP pellets are causing algal blooms – can you quote your source?
The problem with the old metaldehyde pellets being used by water is the metaldehyde is very difficult (expensive) to remove from drinking water.