Garden myths - slugs by Peter Harper
Source: Clean Slate 28 Spring 1998
Of all the questions we get asked about organic gardening, by far the most common is "What do you do about slugs?". There are a combination of tricks that have worked for C.A.T.’s gardeners when faced with their number one pest!
The following is extracted from C.A.T.’s Tipsheet Slugs! What can you do about them? by Peter Harper.
Slug lifestyles
To control slugs effectively, it is handy to know something of their habits and patterns of foraging. Slugs dry out easily, so they tend to shelter in damp places during the day, coming out to feed at night. From their shelters they search apparently randomly for food, but once they have found something palatable, they tend to stay there grazing until dawn, usually returning to the same shelter.
On the following night they are able to follow the previous night’s slime trail back to the same grazing site. Other slugs can also pick up this trail, and the result tends to be a concentration of slugs on certain ‘victim’ plants or patches of the garden. They have fairly strong preferences, as gardeners well know, going for young shoots or slightly wilted or damaged foliage. Although they’ll eat most things if really hungry, they obviously prefer some plants to others - delphiniums, French marigolds and lettuces being particular favourites! They are most active in spring or early summer when it is warm but humid, and unfortunately this is just the time when plants are most vulnerable.
Hand picking
A trip out into the garden with a torch after dark to pick the little blighters off can yield huge numbers of slugs. This is labour-intensive and a bit messy, but effective in breaking the back-and-forth habit of slugs who have established both a shelter and a good food source. It is best combined with other methods (see later). Carried out every few days in spring, it also gradually reduces the population.
The beer method
This involves nothing more than placing a shallow saucer or dish of beer with the rim flush with the soil. It is an ideal thing to do with the horrible yeasty sediment at the bottom of home-brew bottles. Slugs are drawn to the beer and drown. The great advantage of this method is that if you’re squeamish about killing slugs, it does the killing for you, and you can even convince yourself that it’s a pleasant death.
The comfrey method
This is a method developed at C.A.T., and seems very promising. In the springtime, slugs are particularly fond of wilted comfrey leaves. Comfrey grows strongly in the spring and is readily available.
About a week before planting out, a pile of comfrey leaves is left in the centre of a plot. The slugs will soon find it and more and more will follow the slime trails until on about the fifth night the pile will be absolutely heaving with slugs. These are removed and disposed of. On succeeding nights, further slugs are removed but there will be far fewer. Finally, the pile of leaves is removed (and composted) and the plot is planted up, with a continuous ring of comfrey leaves laid around the edge of the plot. The comfrey acts as a decoy to any remaining slugs who may move onto the plot from outside. After this, only occasional night-time checks and renewal of the leaves every week or so are necessary.
Day traps
These are simply artificial shelters for slugs that can be easily inspected. We have found the most effective traps to be lengths of slabwood obtained free from sawmills, i.e. the round-sided bits that are left behind after sawing a log. ‘Proper’ planks of wood are not so good because they tend to curl up in the hot sun and don’t keep so damp underneath.
The pieces of slabwood are placed between crop rows, where they provide handy mini-paths. You simply turn them up from time to time and remove the slugs.
Other methods
Slug pellets are without doubt very effective, but as they are poisonous to other animals we do not use them or recommend their use. Aluminium sulphate, sold under various trade names such as Fertosan and Nobble, is less poisonous, but we find it rather feeble in its effects. A new method recently introduced is biological control by tiny worms called nematodes, which are available through the Organic Gardening catalogue, River Dene Estate, Molesey Road, Hersham, Surrey, KT12 4RG, Tel: 01932 253666.
Further Reading
All the following titles are available from C.A.T. Mail Order, Tel/Fax 01654 703 409 or email Sabrina Wise on Sabrina@catmailorder.demon.co.uk
• -Slugs! What can you do with them? Tipsheet, Peter Harper, 30p.
• -Organic Gardening Poster Magazine, Maritsa Kelly and Peter Harper, £3.50.
• -Organic Growing Resource Guide, £2.00.Addresses and descriptions of organisations, products, and publications for every type of natural gardening need.
• -Pests, How to control them on fruit and vegetables, Pauline Pears and Bob Sherman, HDRA/Search Press, £4,95..
