We've got ants in the greenhouse this season, they're damaging the seedlings and getting in the way of work. I tried sprinkling wood ash on the soil - didn't help. Maybe you could suggest some kind of treatment or a folk remedy?
You totally barked up the wrong tree with the ashes! The folks above got it right - ants aren't really the enemy themselves, they're protecting aphids, and those are the ones sucking the juice out of your seedlings. Try treating your plants with an insecticide like Aktara or Confidor - that'll kill the aphids and destroy the whole point of the ants guarding them. If you want something natural, garlic infusion or celandine decoction works, but you gotta spray several times! The main thing is fighting not the ants but their "cows," then they'll just take off on their own!
I've been on the road for 25 years now, and I've been fighting ants in the greenhouse for about 15 years probably. I'll be honest with you, ash won't do any good, they'll just go around it. The main thing to understand is that ants themselves aren't really dangerous, it's the aphids they breed there and protect that are dangerous - those are what destroy the seedlings. So you need to fight the aphids at the same time or even first and foremost. I use preparations like Aktara or Confidor, spray according to the instructions and the ants leave on their own because the food source is gone.
From folk methods, this one's been proven to work - put baits with boric acid and sugar in the greenhouse, the ants will drag it into the nest and poison themselves. Mix a tablespoon of sugar with a glass of water, add half a teaspoon of boric acid, pour it into a saucer and place it in problem areas. Change it every couple of days. Diatomaceous earth also helps really well if you can find it - sprinkle it around the nests, then the ants leave. And if things are really bad I grab ready-made ant baits like Muracid or Medvetoks - they're cheap, work effectively. Just remember to ventilate the greenhouse after treatment and follow the waiting periods if you're growing vegetables there.
I agree that ash doesn't do much good - I tried it too. The main thing people missed above: ants themselves don't actually eat plants, but they protect aphids, which are the ones actually damaging the plants. In our greenhouse, a combined approach helped - first I treated the soil with something like diazinon-based products, and at the same time I sprayed the aphids with insecticide, and now for the second season in a row the problem hasn't come back. If you want something gentler, you can try a boric acid solution or even just put wet rags next to their nests - the ants will take them as a burrow, and then you can pull them out together with the colony.
Someone above correctly pointed out about aphids - that's really the main problem. I saw a similar situation in the hospital when people were fighting insects wrong, and I can confirm: ants don't eat seedlings by themselves, but they actively breed aphids like livestock. Ants protect aphids from predators, carry them to healthy plants, and that's when the real damage starts. They'll just walk around the ash, like someone already said correctly.
I like the two-step approach. First treat the plants with an insecticide - like Aktara or Confidor, they work pretty well against aphids. At the same time you need to break the connection between ants and aphids - sticky tape or traps around the plant stems work great for this. Ants won't be able to climb up - and the aphids will be left without protection and their "milk cows". In practice this works way more effectively than chasing the ants themselves.
If you want to go without chemicals, try boiling water on the anthill if you find it in the greenhouse - it works, but doesn't guarantee complete relief because colonies can be scattered around. I'd still combine it: insecticide on the plants plus sticky traps. We did this for the 2026 season in our department with houseplants, and it helped.
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