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February is the optimum month in which to start preparing your garden for the re-emergence of your perennial plants and this means early treatment against pests like slugs and snails. Hostas are no different from the rest of your garden perennials in that they represent juicy offerings to slugs. However, you are more likely to notice the damage done in a hosta leaf than in something like a delphinium leaf. Treating your garden against slugs and snails at this early stage will disrupt their breeding programme and prevent a population explosion later on.

We use slug pellets because they are very effective. We have used nematodes in the past, one application can often last an entire season. However, these biological agents will only attack the slug population, leaving snails untouched. It is also worth reiterating how important it is to get familiar with the micro-climates in your garden as this can help you identify areas where pest damage is more likely to occur.

Applying pellets
We apply slug pellets when top-dressing our sales stock and collection plants. It is important to ensure the pellets are in the soil rather than on top as 90% of problem slugs live underground and will encounter the pellets as they emerge. Subsequent applications are only required in specific areas of the nursery and garden that are particularly prone to attack. In these situations we generally use a few pellets in a jar (laid on it's side) with a neck big enough for slugs and snails to crawl in and out. This keeps the pellets dry and the active ingredient, metaldahyde, doing the business for longer. The jars are easily concealed amongst the foliage so this method is also useful for potted hostas.

If you are too late with your first application and slugs have already nibbled the emerging shoots then wait for them to come through and cut the affected leaves off. One of the best things about hostas is that they will come back providing they were not too badly damaged. If all else fails then there is always next season.

Identifying the culpits
So, how can you identify which pest is causing damage to your hostas?

Slugs
Slug damage shows as lace leaves on emergence and the damage is caused mainly in the spring.
As soon as the weather warms up the slugs emerge to breed and feed. If they find pellets before delicious spring shoots, it follows that they cannot breed. Once your plants are above the ground and the leaves unfurling then slug damage becomes less of a problem. By the way, not all slugs are bad… leave the big black and brown ones as they have a preference for the common grey slugs that do like your plants!

Snails
Snail damage shows as large gashes in the leaves throughout the season.
These pests have voracious appetites and can wreak havoc in areas of the garden where they like to dine. However, they do not like to dine in public so don't expect to catch them in the act of destroying your plants. Expect to find them sheltered in cool, shady spots away from the heat of the day. It is a good idea to regularly turn over pots, containers and undergrowth to disturb snails and offer them up to eagle-eyed thrushes.

Vine Weevils
Vine Weevil damage shows as notches nipped out along the leaf edges.
This is done by the adult weevil, which feeds at night and does not fly. Its' larvae feast on plant roots to devastating effect. The larvae are white, about ½" long, with brown heads. We have found that they are most likely to cause damage in potted plants, probably because they like soft peat. To combat this we always add 20% sharp sand to our potting mix.

Further information
The following are a selection of links from the many websites with information on the subject:

• The RHS advice pages
• Gardenseeker pages on slug pellets
• All about Metaldehyde
• Slug Awareness Campaign
• What's wrong with slug pellets?
• Nemasys website
• Organic pest control methods from Harrod Horticultural