Slugs and, to a lesser extent, snails are the nemesis of hosta gardens. A shade garden is the ideal environment for these critters so they tend to thrive along with the hostas.

At this point in time, there is no single, all-effective way to eliminate slugs in the hosta garden. In order to gain some level of control over slugs, you need to attack them at one (or more) of three points:

  1. Get Rid of the Slug
  2. Change the Growing Environment
  3. Reduce the Food Supply
  4. Mr PGC Slugs vs Hostas Rating

There are probably a hundred  different (home remedies) approaches to getting rid of some of the slugs in your hosta garden. All of them seem to work to a certain extent but none of them do the job totally. Here are a few of the more common approaches:

  • Trap Them - We have all heard about placing a tray of old beer at soil level. The slugs crawl in and drown. They are actually after the yeast so baker's yeast may also work.

    Place some pieces of wooden board in the area with the slugs. During the heat of the day, turn the boards over and kill the slugs with a mixture of one part bleach to nine parts water. Some people use vinegar and other low toxic materials to kill them. Be careful in the over use of salt in the garden.

    Take a roll of newspapers and put a rubber band on it. Soak it in a pail of water for a few hours. Take off the rubber band and lay the newspaper in the slug area. They will crawl between the pages of the paper. Roll it up and dispose of the paper and slugs on page 4.

  • Direct Killing - Spray the slugs with the dilute bleach solution directly on the plant. The downside of this is that the critters feed at night. Use a flashlight to find them but be sure to tell your neighbors what your are doing. Explaining to a non-gardening policeman can be embarrassing.

  • Exclusion - There are several ways to prevent slugs from moving from plant to plant in your garden. Since they are soft bodied creatures, they do not like to crawl across any rough surfaces.

    You can spread things like wood ashes, crushed egg shells, diatomaceous earth, cinders and other coarse materials around the base of the plants. The down side is that, after a few rains, these materials may lose their effectiveness. They also do not stop the slugs that are already on a particular plant.

    Copper ribbon is now available in most gardening catalogs. Cut it into pieces and place it around the base of especially valuable specimen plants. When the slug attempts to cross the copper strip, it gets a galvanic response which give it a little tingle.

  • Poisons - There are a few pesticides that are specifically labeled for slug control. A common one comes in the form of a granular bait which, when eaten by the slug, causes it to lose its ability to produce slime. Another one is based on iron phosphate and, may have some fertility effect for the plants too.|

    In Great Britain, a parasitic nematode is available. Unfortunately, this material is not yet legal for use in the U.S. Some people have purchased this material while on a visit to England and have used in their gardens. This could be great or it could be very dangerous.

    In the U.K. it appears that the nematodes only affect slugs. However, until studies are done in North America, we do not know what other species may be affected here. Most of the very serious horticultural insects (gypsy moth, Japanese beetles, European chafer, etc.) and diseases (Dutch elm disease, chestnut blight, etc.) have been inadvertently imported from other parts of the world. 

To thrive, slugs need a cool, moist environment preferably with plenty of decomposing organic matter. If you have slugs, then you have the proper environment for them to feed, reproduce and survive. The number of slugs you have is determined by how well your environment fits the needs of the slug.

Water - In general terms, the wetter your garden, the greater the slug population. Hostas need a fair amount of water to thrive but many people use far too much irrigation water. The use of organic matter incorporated into the soil will help minimize the need for a lot of irrigation. The key here tends to be finding a balance where you water enough to keep the hostas happy but not so much that the slugs go wild.

Mulch - Wood chips, shredded bark, cocoa bean hulls and other organic mulches provide a lot of benefits in the garden. However, they can also be a great home for slugs. If you have a slug problem, avoid using too much mulch. When the mulch begins to rot and stays moist all the time, rake it off and put it in the compost bin. Replace it with a thin layer of fresh mulch. This will dry out quicker after rains and make it less inviting for slug families.

Although it seems hard to believe sometimes, slugs have preferences in what they eat just like any other creature. So, you can choose to plant only those hostas that do not seem to be bothered by slugs. The tough part is determining which hostas fall into this category.

There are lists and lists of hostas that are either always eaten by slugs or never eaten. Sometimes the same cultivar will appear on both lists. How do you know what to do?

Well, generally, the thicker the texture of the leaf, the lower the level of slug damage. Thin textured hostas, often the highly variegated types, tend to be most desirable for our legless friends.

You may have to develop your own list of slug-resistant hostas for your own garden. The available lists will give you an idea but will not be fool proof for your conditions. Your shade may be darker, soil less well drained, irrigation practices more liberal and mulch layer thicker than the average garden. These will created a better environment for the slugs resulting in damage to cultivars that are normally not bothered. 

We have tried to categorize hostas in terms of their susceptibility to slug damage under typical growing season conditions.

As part of the hosta cultivar listings in our HostaHelper website, we have given ratings to certain plants according to the level of damage often encountered as follows:

Hosta cultivar descriptions that include this button are those that are considered resistant to damage by slugs. Generally, these hostas have thick or above average substance i.e. texture or thickness of the leaves. Although they are not immune to damage, under general garden conditions, they usually come through the season unscathed. However, if you build a great environment for slugs (i.e. excessive mulch and irrigation), they too may be damage.

Cultivars with the "Slug Bait" button are those that tend to be damaged the most by slugs during a typical growing season. Usually, this relates to the thickness i.e. substance or texture of the leaves. Those with thin, tissue paper like leaves tend to be the ones first attacked by slugs. Again, if you maintain a poor environment for slugs (i.e. minimize rotting mulch and control irrigation), these cultivars will experience less damage.

 

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