Slugs are a particular problem in spring and early summer when the weather is typically warm and wet. This is also the time when we gardeners have seedlings and young plants for them to munch on. Slugs are most active at night and seem to prefer feeding on young growth. Unlike snails, slugs can burrow beneath the soil surface, so surface barriers such as coffee grounds, eggshells or gravel aren’t as effective as they are against snails. What’s the best way to protect your young plants? Here’s a few suggestions:
Encourage wildlife
Making your garden more wildlife friendly is a great way to keep your garden in equilibrium. Both amphibians and reptiles – such as slow worms – can help to keep down slug populations. Other predators of slugs include birds, particularly song thrushes and starlings. To encourage amphibians and reptiles make a log pile, lay slate tiles over long grass for slow worms to bask under, and dig a pond. Birds can be encouraged in by planting a mixed native hedge, having areas of water for frinking and bathing, and growing caterpillar foodplants so there’s plenty to feed their chicks in spring.
Use a deterrent
There’s not enough evidence to show that barriers such as coffee grounds and eggshells are effective against slugs, but copper can work, according to Dr Hayley Jones, who leads the research into slugs and snails for the RHS. To protect plants in the ground, look for a deep collar as slugs could go underneath the ones resting on the soil. Check that you are buying a product that has real copper in it and if you’re using it on a pot, use a thick strip. Slugs and snails will put up with some discomfort to get to a plant they really like so it’s more effective to use a wide strip of copper. Other deterrants that seem to work well include plastic slug and snail collars, which slugs don’t seem able to climb over.
Water in the morning
Watering plants creates damp soil and makes it easier for slugs to travel. As they’re most active in the evening, it’s a good idea to water seedlings in the morning, instead.
Pick slugs off plants
Check your seedlings at night with a torch and pick off any slugs. Move them at least 20m away to somewhere like a compost heap, to stop them finding their way back to your plants.
Mulch the soil
Cover the surface of your border or veg bed with a layer of mulch. Instead of acting as a barrier that slugs can go over (if determined enough) or underneath, mulch across the entire surface makes it much more difficult for slugs to move around. This also has the benefit of improving your soil. Straw-based mulches work well for this.
Grow seedlings indoors
Don’t plant seedlings out too early. The bigger and stronger a seedling is when it’s planted out, the more it will be able to withstand the occasional slug attack.
Use a biological control
Buy nematotodes to kill slugs. Check the instructions as the soil needs to be a certain temperature for the nematodes to work. It might be necessary to do a couple of applications over the growing season. This should only be used as a last resort, and in specific areas, as not all slugs are pests. Some slugs do a useful job, feeding on dead plants.
