Slugs and snails preventions


Hello, I live in Scarborough by the bluffs. I have planted a shady garden with many of hosta plants 2 summers ago. I use mulch as a way of weed control. The soils is mostly clay. My hostas thrived last summer. This summer, their leaves are full of holes. I believe to be the result of snails or slugs even though I found only a few snails in the soil. My questions are: 1. If the damage on the hosta leaves is not by snails, what could it be? 2. Is there any a preventative measure I can do this fall? I thank you in advance to answer my questions.


Unfortunately, hostas and slugs are perennial partners in our Toronto gardens; just because you haven’t seen them in your own garden, doesn’t mean they are not there already. Slugs are just snails without their shells. They overwinter in the soil and lay egg masses in leaf litter, compost piles, under rocks & stones or on the soil under mulch. Unfortunately, there is no magic cure to eliminate all the slugs on your property.  Your best bet is to check the area around each of your Hostas.

We have handled this issue in several queries on our website. Simply type slugs into the Find it Here box located on the right side of our home page to find a number of our archived posts.

The one thing I would stress from personal experience is that while no hosta is totally immune to slug predation, the “slug resistant” varieties now available, with their thicker, corrugated leaves, do seem to attract fewer of these pests. Below is one of our  previously published answer:

The best way to get rid of slugs is to hand-pick them in the early evening, about 2 hours after sunset, as the critters are more active at night. Go out with your flashlight, and examine the bases of pants, backs of leaves and between the rows of your vegetable garden. You can use a spoon to loosen the slugs from the plant, then put them in a pail of soapy water. Other methods, e.g., trapping them and spreading diatomaceous earth in areas they like to hide (this acts as a barrier as the particles are scratchy), may also be effective. See the Government of Canada’s article, Slugs and snails.

  • Choose plants that are resistant to slugs – e.g., see All About Slugs’ Slug and snail resistant plants. And ask your local nursery for plants that are less likely to be attacked by slugs.  For example, while no host is slug-proof, there are some varieties that are more resilient to slugs (in particular the varieties with blue leaves that are thick and puckered).
  • Water the garden less frequently and more deeply, and try not to water late in the day – morning is best (slugs are less active then)
  • Slugs gather under mulch and other debris, and among weeds, so keep the garden area as tidy as possible

Finally, a 2018 2019 article of interest is the University of California Integrated Pest Management Program’s How to manage pests – pests in gardens and landscapes – snails and slugs as well as How to Kill Snails and Slugs- A Definite Guide

Examine your plants often for signs of damage from slugs – look at the whole plant, from top to bottom, and both sides of leaves. If slugs have started to appear – take out your flashlight and go hunting!

November 12, 2021