Has anyone tried this? A recent issue of Mother Earth News had a tip from a reader in my neck of the woods who has tried everything to keep slugs away and found that cut boughs of rosemary laid around plants kept slugs from attacking.
I have no rosemary on our farm, but I'm thinking of investing in some. I never plant them bc I don't like to use rosemary in cooking and am not especially fond of their fragrance, but if I can fend off monster slugs? I'm in. I'll be a rosemary fool.
I don't know if this works, but I do know about rosemary. I love it and keep a few bushes around.
Rosemary has a 'tar' substance on the green foliage. I don't know if there is a technical term for this tar ('glandular secretions' perhaps?), but you can find it on certain aromatic plants. I do know that these secretions are found on the trichomes of a plants exterior. Tomato plants are coated with this tar, and if you work with them for an extended time, you'll notice the buildup of black & green/yellow tar on your hands...and on your clothing. The picture below is one of my workshirts, stained by tomato tar. Basil is another plant that 'tars'. Rosemary also tars, and rosemary tar has the additional quality of being kind of tacky when you rub it between your fingers.
I've found these tars are almost universally irritating. The scent of the tomato tar alone makes my sinuses burn and invokes a runny nose, for instance. I'll get a burning sensation on my skin, though I sometimes work with so many plants that by the end of the day my hands are black like I dipped them in motor oil.
It keeps most ruminants from nibbling on these plants, and only insects will venture a bite.
I've never observed slugs on or near a rosemary plant, so perhaps there's merit to this - the chemical could irritate the slugs skin.
I can't speak to Rosemary as a slug repellent. But I used to have a terrible slug problem. I got rid of them by planting wormwood (Artemisia Absinthium). I have had one plant in a bed separate from my vegatable garden for about ten years now. At first I thought dry weather had killed them off because the change was so dramatic. But they have never reappeared.
A word of warning about Wormwood. The roots secrete thujone just like a black walnut does. This will suppress the growth of other plants. Tomatoes are particularly suseptable. I have used the problem as a solution. My Wormwood is keeping a patch of peppermint contained.