slug prevention

Asked August 18, 2015, 10:11 AM EDT

I have problems with slug damage all over my yard. They mainly like hosta, ladies mantle, and lungwort. Is there a preventive measure that I can take in the spring? It's a 2edged sword with shade loving plants. They like it shady and the dampness encourages the slugs. I hand pick them off but my gardens are huge. I use sluggo, but it doesn't help much. Any help is appreciated, Thank you

also is it too late to add aluminum sulfate to hydrangeas. I just read that it will aid in flowering. I have 4 that don't produce flowers at all. They are in different parts of the yard

Broome County New York integrated pest management insect issues slugs horticulture

3 Responses

Aluminum sulfate does not aid in flowering; rather, it changes the pH of the soil, encouraging hydrangeas to produce bluer coloured blossoms. Before adding aluminum sulfate, you should have the soil tested in order to assess how much to add in order to reach the level of pH you want for the bloom colour. Then additions would be specific in amounts and timing to reach that level, and it usually takes soil a season or two to adjust.

Slugs are pretty common! Any "solution" will not "eliminate" them: they are part of the garden world. What we can do, though, is prevent them from getting to our plants and/or reducing the numbers to where we can live with the "damage" they're doing...

They don't like crossing copper so putting bands of copper around the base of plants can stop them. Some people suggest sprinking substances like diamotaceous earth around plants: this is volcanic dust that is very sharp and cuts the slugs as they attempt to cross it. I worry about what it does to the worms in the soil, myself. I have had good success with a product like Slugo (it contains iron phosphate like Slugo). One needs to sprinkle it after heavy rains etc to keep it active, but it has reduced the slug feeding over a couple of years. You can put a board (or two or three) down near where the slugs are active. In the morning, lift the board and you may find several slugs under it... simply remove and dispose of them. Any solution will require a fair bit of time to gradually reduce the population to a level you can live with.

Good luck

Thank you for your quick reply Glen.

About the aluminum sulfate, I understood that it aided in producing flowers. Guess not. I should have known. Is there anything that I can do to get these hydrangeas to bloom?


Dear gardener,

The primary reason hydrangeas fail to bloom is pruning at the wrong time. Some hydrangeas bloom on the current year's wood, pruning in early spring is usually recommended. However, other hydrangeas (particularly the coloured varieties) bloom on one-year old wood. These should be pruned immediately after the bloom so that the buds will set for next year.