Slowing down slugs
This project is now CLOSED for 2019.
We should have results for you shortly, and are planning for 2020!
Preventing slugs and snails from nibbling on veg is one of gardening’s most familiar challenges. With many of us looking to reduce the use of chemical controls, home remedies and other methods are becoming more popular again (and many never left) – but how well do they actually work?
Join in with the Buzz Club to investigate!
The Royal Horticultural Society recently looked at what might work for reducing grazing damage on leafy crops, although none of the tested remedies performed strongly. We plan to look at another angle, focusing on ‘remedy’ controls used to protect plants that are fairly robust once established, but suffer damage badly in early stages. E.g. peas, beans, squashes - where slugs are at their most frustrating when they eat your new seedling off at the base, but are less of a problem later when the stem is robust and unappealing.
New plants. Exciting, but delicious. Particularly annoying to lose them at this stage if you do not have a lot of space for seedlings - like Linda's grow bench here.
Established plants. Tougher overall, certainly less likely to be chewed through at the base.
We are going to look at six alternative methods of slug / snail control. To make sure plenty of people can take part, we are not going to restrict what plant you should be growing to a single variety. Only that each experiment you do should use the same type of plant. This can be one that you typically grow, or a new one you fancy trying out, as long as it fits the criteria:
Grows from a large seed.
Produces a fruit or seeds that are the main crop.
(A large flower like a sunflower would also fit.)
Can be grown in a 3L pot.
(You can do the project in the soil, but it is harder to apply the treatment methods.)
You will also need sufficient space in your garden / allotment / green space to keep the plants in approximately the same place (e.g. distance from other plants, from undergrowth, etc). This will keep the environmental conditions for each plant constant on your site, so they are equally exposed to slugs / snails, and also get the same amounts of warmth / light.
Taking part in the project
When you have chosen your plant(s), you will need the following equipment:
Fresh compost / clean soil
Pots to grow plants in (3 litre)
Saucers for under pots to conserve water*
* Unless you are growing squashes, which do not like to sit in water.
You will need to sow at least two plants. One 'control' plant, which will not have any slug / snail treatment applied to it. One plant for each treatment method you intend to test out (see below). We also advise you plant a couple of extra seeds, in case any of them fail (whether you do this by planting more than one in each pot, and keeping the stronger sprout, or plant them all seperately is up to you).
Plant the seeds in your usual way. Whether you tend to start them off on a windowsil, in root-trainers, or into the pot immediately - it does not matter as long as the plants are transferred to the garden, and the treatments applied, when the seedlings start to show.
When the seedlings have appeared, record the date and apply the treatment(s) you will be testing. The six options are show below (using broad bean plants, since those were the ones I have now!):
Copper tape. Sticky-back tape, available from many supermarkets, DIY and gardening stores. Cut enough tape to make a slightly-overlapping band around the centre of the pot. Tape should be clean and shiny.
Copper coins. A tight double ring of 1p (or 2p) coins around the pot, either glued on or attached with double-sided tape (the copper has to be able to touch the slug!). You will need two rows, tessellated, to make sure there are no very thin areas to act as bridges.
Make sure to clean coins first (they should be shiny) You can use lots of common household products to do this – cola and ketchup being two examples
Plastic bottle greenhouse. Cut the bottom off a clear plastic bottle (ideally a large one, 1L or more). Carefully push the bottle down into the soil to stabilise and stop slugs crawling under it; stabilise with a stick if needed. Put a small piece of mesh (or garden fleece, or netting) over the top of the bottle, hold in place with string or an elastic band to allow ventilation.
Garlic mulch. Make a garlic mulch to surround your plants. Buy a large bag of cheap garlic (or use up leftovers from the previous year), and put a couple of bulbs into a food processor. No need to peel, just chuck the whole thing in and blitz until it is shredded. Put a layer of garlic over the pot soil surrounding the plant.
Sharp grit. Put a layer of sharp grit / gravel over the pot soil. You can also use washed crushed up eggshells if you have enough to make a good layer (important to wash them, or it’s just a tasty egg treat for the snails!).
Wool pellets. Available from many supermarkets, garden centres and DIY shops. Put a layer of pellets around the plant in the pot and water them so they expand and make a wooly mulch ‘carpet’.
When you have your experiment set up (see below for an example with all treatments in place), then you just need to maintain the plants for six weeks. Water as appropriate for the type of crop, and keep an eye on them.
What to record
1) The date you appled the treatments to the plant pots.
2) If a plant died, when it died.
3) If a plant died, did it die from slug / snail damage, or not*?
4) Which plants survived to 6 weeks?
5) How tall is each plant at 6 weeks?
6) Do they show any signs of slug / snail damage?
i. If so, how many leaves are affected?
Ii. How many leaves are not affected?
All treatments, with broad bean plants.