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!
We go round in the evening just after dark with a torch and pick them off the paths and plants. This is especially effective after rain. Our record is over 390 on a mild November evening! What you do with them then depends on how squeamish/heartless you are. 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. If you collect them in a bucket with salty water in the bottom, the deed is done for you. Don’t pour the water on your garden though. 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. We found dozens over-wintering under the rim of a fibreglass waterfall. 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.
When buying a new Hosta, be vigilant. Check it regularly and at the first sign of a leaf being eaten, search around 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. You need to begin early in the season since the wash takes 4-6 weeks to work. 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 in a capped bottle.
- 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.
If, when you search for slugs you see lots of glistening trails/bits amongst the soil granules surrounding a hosta it means that there are slugs (usually the little black ones) living in the soil. Watering the soil around the crown of the hosta with a 1-10 solution of household ammonia to water (500ml bottle of ammonia to 5litres of water) kills them within seconds, even if you can’t see the results. Add the ammonia to the water. Ammonia, diluted like this is harmless to plants.
Many people, (perhaps most) dislike using the usual blue metaldehyde slug pellets because of their effect on wildlife. If you do use them, they can be very effective early in the year (mid-February) before wildlife is up and about or during any winter mild spell. As a last resort, apply pellets very sparingly and not right next to your hostas (they are an attractant!) Putting them inside a jam jar on its side helps to keep them away from pets and wildlife. Use a less-poisonous pellet – there’s one based on ferric (iron) phosphate which simply makes the slugs and snails unable to eat. You should be able to find it in a local garden centre. The one we’ve bought says on the tub: – ‘Growing Success Advanced Slug Killer Pellets – certified for organic use’. Another less toxic pellet is based on aluminium sulphate but don’t scatter it on paths. We’ve found it leaves an unsightly crystal deposit after rain.
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. Customers 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. We find this successful. You can buy wool pellets from most garden centres. Website is www.sluggone.com,
Pine needles or holly leaves can help.
You can use upturned plastic pot saucers or empty plastic sacks weighed down at the corners as traps. Beer traps work, both for slugs and snails. Pour 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.Buy the very cheapest supermarket own brand beer you can find. The weakest works as well as the strongest. The beer we use costs about 50p a can. You will need to empty the cartons 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.
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: www.nematodesdirect.co.uk. or from Amazon. Apply from April through September. Plan your application carefully since packs have a very short ‘use-by’ date.
Vine Weevil Control
Vine Weevils can occasionally be troublesome, both in container and garden grown hostas. The adult beetles bite semi-circular notches out of leaf edges, whilst the fat, maggot-like larvae eat the roots. The adult weevils are, like Lily Beetles, very difficult to eradicate except by finding and killing them. The grey-black weevils are night-feeders so may be seen whilst searching for slugs and snails with a torch, although they seem to prefer dry nights to wet ones. They tend to drop off a leaf at the slightest movement so catching them between finger and thumb seems to work best. Or you can try to catch them in a container as they fall. Liquid Vine Weevil killer can be bought at most large garden centres but is not effective against adult weevils. Apply to plant roots with a watering can April through September to kill the larvae.
The most effective solution to the problem is to apply vine weevil nematodes, available through Amazon and other on-line garden retailers. Garden centres tend not to stock them because they need to be kept refrigerated until use and the ‘use-by’ date is very short.’
Container grown plants can be protected by using horticultural or alpine grit as a top dressing/mulch. This deters the weevils from laying their eggs in the pot.