Slug and Snail Control
Sometimes it seems there are as many remedies to the slug and snail problem as there are hostas! Here are some for you to try.
Find the culprits!
This is essential, before you even think about barriers. Numbers of slugs and snails must be reduced to stop them breeding. Here’s an excerpt from a recent email endorsing this advice:
‘Just wanted to say after taking your advice last year about going out and hand picking off slugs and snails what a huge impact it has had on my garden. I went out most nights for weeks and collected wait for it …. well over 2000 . Wow what a difference this year. Last year not only my hostas but the irises were eaten before the buds opened. This year full flowers!’
So begin by searching for slugs and snails in the evening just after dark with a strong torch and pick them off the paths and plants. This is especially effective after rain. If you release them somewhere else, make sure it’s over 30 metres (100ft.) away from your garden. Experiments show snails have a homing instinct! If you can’t bear treading on them, (putting them in a plastic bag first saves mess), bag them up and throw them in the bin. Get to know where slugs and snails like to hide – anything plastic such as plant pots or sacks in a relatively undisturbed and cool place will soon become a mollusc hotel. They also enjoy hiding in the heart of spiky plants such as phormiums, astelia, grasses and kniphofia (red hot pokers). Or, of course, at the very base of hosta stems themselves. These can be winkled out with a knitting needle or plant support. Or they can be sprayed with dilute ammonia (see later).
When planting a new Hosta, be vigilant. Check it regularly and at the first sign of a leaf being eaten, search around in the evening until you find the slug or snail responsible. Quite often it will only be one but finding it may take checks over several days.
Spraying plants with a garlic wash is one of the most effective ways of deterring slugs and snails. It’s also a root stimulant and protects against aphids on other plants. It’s best to begin early in the season since the wash takes 4-6 weeks to become absorbed into the plant. Here is the recipe:
• Crush two large garlic bulbs (not cloves), in a plastic bag to save mess.
• Add to 1 litre of boiling water in a pan.
• Boil for 10 minutes.
• Leave to cool outside to avoid a lingering garlic smell in your kitchen.
• When cool, strain into a sieve.
• Store the garlic solution in a capped bottle, preferably brown, to stop mould forming on top.
• Add two tablespoonsful to 1 litre of water in a spray bottle.
• Spray your plants every two weeks or so on a dry evening so that the garlic solution stays on the leaves longer and can be more easily absorbed.
A microscopic nematode or eelworm can be watered onto the soil. It is effective against soil living slugs but not against snails. ‘Nemaslug’ is available on the Web. Google ‘Nematodes Slug’. Apply from April through September. Plan your application carefully since packs have a very short ‘use-by’ date.
Since slugs find their food by smell, a 1-10 solution of household ammonia to water (500ml bottle of ammonia to 5 litres of water) can be sprayed on the leaves to disguise their attractive scent. Spray each evening for instant protection. Ammonia diluted in this way will not harm your hostas but will kill slugs on contact. Useful for those newly hatched slugs that are hard to pick up and those hiding at the base of leaves. As a last resort, watering the soil around your hosta with dilute ammonia will kill the soil living slugs but bear in mind it will also kill worms.
Metaldehyde slug pellets are banned in the UK from spring 2022. If you have any left, you are still allowed to use them in permanent greenhouses. If you still want to use pellets, there’s one based on ferric (iron) phosphate which simply makes the slugs and snails unable to eat. A two year RHS trial (2017) showed that it was more effective than metaldehyde pellets when used on hostas.
Some people have told us that porridge oats have the same effect as ferric phosphate pellets – they swell up inside the slug/snail and they can’t eat. Only useful if you don’t have wildlife or pets that may polish them off first.
Barriers work best when applied early in the season before the first leaves are fully out. Then you can be sure you are keeping molluscs away rather than trapping them inside the barrier.
Copper tape. You can buy this at garden centres although it’s quite expensive. Put it round the base of pots (an electrician customer told us it’s best when in contact with the ground) or for plants in the garden cut the rim off a large plastic pot, place around the plant and stick the tape to that. Hosta growers have told us that a few twists of stripped copper wire works just as well.
Vaseline or WD 40 smeared or sprayed on pots is also reputed to work.
Something gritty around the plants. Most types of gravel or grit are too coarse to work well. The finer the grit the better, Try cactus grit or poultry grit. We’ve had some success with used coffee grounds (coffee shops may give them to you). They work well until rain turns them into a sludge.
Sheep’s Wool. This can be successful until the rain turns it into a soggy mat. You can buy wool pellets from most garden centres. Google ‘Vitax Slug Gone Wool Pellets’ for online stockists.
Pine needles or holly leaves can help.
Shade Netting or Landscape Fabric. Place a piece of shade netting or porous landscape fabric at the bottom of a pot to cover the drainage holes before you plant. This stops slugs (and worms) from entering the pot from below but still lets water through.
Beer traps work, both for slugs and snails. Buy the very cheapest supermarket own brand beer you can find. Pour the beer into a container with its rim at ground level. Yoghurt, coleslaw or cottage cheese cartons work well with no more than 4cm (1.5”) of beer in the bottom. Tip: Put the top of the carton on while you pack it in its hole. Remove it carefully to avoid soil falling into the beer. We use ‘Gu’ dessert glass containers. They use very little beer but are still successful.
Since it’s the yeast in beer that attracts the slugs you can make your own bait. One recipe suggests 2 cups water, 2 tsps sugar or honey, 2 tsp flour,1 tsp dried yeast granules.
You will need to empty your traps every 2-3 days. When a trap fails to catch anything, move it to another spot. Disposal of contents is easy. The birds, hedgehogs and frogs do it for you.
Plastic sacks or upturned pot saucers can also be used as traps. Check every day.