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Slugs in the greenhouse are common, and if overlooked, they can destroy your plants. The good news is there are simple steps you can take to control them.
Slugs in Greenhouse – What to Do
Slugs love to chew on leaves with a bonus of a slime trail. Here’s how you can deal with them and protect your plants:
Remove their hiding spots
Slugs hide where it’s dark and damp, such as in the corners, under trays, and around pots. In these areas, you’re also likely to see a pile of old leaves and plant debris. Get rid of them, including anything that holds moisture, like an empty pot with water.
Damp cardboard, wood offcuts, and unused grow bags also give them cover. If you store seed trays or tools on the floor, raise them on shelves or keep them outside the greenhouse.
When there’s less moisture around, slugs find it harder to stick around.
Keep the air moving
Considering the favoured spots of slugs, this makes airflow more important than ever. Open the greenhouse vents during the day, or use louvre windows if you have them. If none of these work for you, leave the door open when the weather allows.
You can also prop up cold frames, use mesh panels on doors, or set up a small fan inside. Another trick is to space the plants out to reduce damp patches where slugs hide.
Good air circulation dries out condensation, which is less inviting for slugs.
Use barriers
These will be your roadblocks for those slimy, tiny creatures. Copper tape is a good place to start. Wrap it around the rim of pots or the edge of raised beds, and slugs get a small shock when they touch it. Don’t worry, it isn’t lethal—it only makes them turn back!
For soil beds, you can go with sharp grit or crushed eggshells. Pour a solid line around the plants you want to protect, not a light sprinkle. If gaps appear, slugs will take the chance, so keep the line topped up.
Set traps
Beer traps are simple. Sink a shallow container into the soil so the rim is level with the ground, then pour in some beer. Slugs are drawn to the smell, fall in, and can’t get back out. Check the trap each morning, and you might find a few ready for hand-picking. And make sure to replace the beer every few days.
Alternatively, you can use boards. Lay down a piece of wood, slate, or even a damp bit of cardboard near your plants. Slugs crawl underneath, and in the morning, you can lift the board and remove them by hand.
Try natural deterrents
You don’t always need shop-bought products to put slugs off. Spread used coffee grounds around the base of plants. The rough texture and caffeine make the area less appealing for them to cross.
Garlic spray can work, too. Crush a few cloves, boil them in water, let them cool, then pour the liquid into a spray bottle. Spray the soil and lower leaves in the evening. The smell keeps slugs away, and you can reapply after watering or rain.
How to Prevent Slugs from Coming Back
The best way to stop slugs settling in again is to keep on top of these small habits:
- Tidy up dead leaves and old pots so they’ve got fewer places to hide.
- Check the edges for gaps and block them off.
- Try to keep the floor dry by brushing away water or raising trays and tools off the ground.
- Do a quick check at night or early in the morning when slugs are out. A fast walk-through with a torch can help you spot them before they do any harm.
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Slug in Greenhouse: Round-up
Slugs are stubborn, but they don’t have to take over your greenhouse. Stay on top of tidying up, improving airflow, and keeping watch during their active hours. Mix in a few barriers, traps, or natural deterrents, and you’ll keep them under control. Consistency is key!
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