Slug Resistant Plants

Standard

Some plants simply send slugs running! Ill.:moziru.com

The true secret to controlling slugs easily is not to battle them with egg shell barriers, beer traps, or other lures, repellents or snares, but to remove the plants that attract them and to replace them with plants that don’t.

The classic case is of course the hosta.

Hosta undulata ‘Albomarginata’ attracts slugs like a magnet.

Hostas are renowned for attracting slugs. Yet in fact, only some hostas are to blame. In fact, three hostas – by far the most popular in our gardens – are the main victims of slug damage: Hosta ‘Undulata Albomarginata’, a medium-size hosta with fairly narrow wavy-edged leaves edged in white, H. ‘Undulata Mediovariegata’, similar, but with a reverse variegation (there is a flame-shaped white marking in center of the leaf) and H. ‘Undulata Univittata’, again with the same wavy fairly narrow leaves, but this time entirely dark green, with no variegation. These are the hostas used for mass plantings, grown by millions in temperate climates around the world, largely because they grow and multiply quickly, making them inexpensive. But they also attract slugs like a magnet.

Slugs actually hide in the roots and crowns of these hostas at night. They also lay their eggs at the base of H. ‘Undulata Albomarginata’, H. ‘Undulata Mediovariegata’, and H. ‘Undulata Univittata’ and young slugs get their start feeding on their leaves. Ruthlessly removing these hostas from your garden can so reduce the slug population in general that even other slug-susceptible plants are largely left alone.

‘Sum and Substance’ is a popular slug-resistant hosta. Photo: http://www.ballyrobertgardens.com

But not all hostas attract slugs. Many are only somewhat attractive to slugs and only suffer minor damage, especially early in the season. And some hostas are out and out slug-resistant. This is the case of many if not most of the modern varieties, since hybridizers selectively breed for slug resistance, but many old-fashioned hostas are slug-resistant as well. H. sieboldiana ‘Elegans’, for example, a well-known and highly slug-resistant hosta, was introduced in 1905! Slugs are not attracted to thick-leaved hostas, nor hostas with blue leaves, for example. Read Slug-Resistant Hostas: Take Your Pick! for a list of over 100 slug-resistant hosta cultivars.

Other Plants

You can almost tell if a plant will attract or repulse slugs just by studying it. Slugs tend to prefer plants with soft, thin leaves. That’s why they do so much damage to seedlings: young plants’ leaves have not yet developed their more leathery final texture. Conversely, slugs tend to avoid leaves that are hairy, tough, fibrous, thick or waxy, as well as those with a bitter taste or with strong odors (many herbs are slug resistant, for example). Oddly, slugs often find plants that are poisonous to humans quite palatable.

Slug-Resistant Plant List

Daylilies (Hemerocallis),  ‘Stella d’Oro’, are almost never attacked by slugs.

Here is a short list of slug-resistant plants. I’ve included mostly perennials, annuals, herbs and vegetables. Most shrubs, conifers and trees, even if they may be somewhat susceptible to hosta damage in their youth, eventually outgrow the damage.

  1. Ageratum (Ageratum houstonianum) annual
  2. Alyssum, sweet (Lobularia spp.) annual
  3. Anemone, Japanese (Anemone × hybrida, A. japonica, A. hupehensis)
  4. Artemisia (Artemisia spp.) zones 2-9
  5. Astilbe (Astilbe spp.) zones 4-8
  6. Bachelor’s buttons (Centaurea cyanus) annual
  7. Bamboo (most species) zones 4-11
  8. Bamboo, heavenly (Nandina domestica) zones 6-10
  9. Basket of gold (Aurinia spp.) zones 3-9
  10. Begonia, bedding (Begonia semperflorens) annual
  11. Bellfower (Campanula spp.) zones 3-7
  12. Bergenia (Bergenia spp.) zones 3-9
  13. Bidens (Bidens spp.) annual
  14. Black-eyed Susan (Rudbeckia spp.) zones 3-8
  15. Bleeding heart (Dicentra spp.) zones 3-9
  16. Bluestar (Amsonia spp.) zones 3-9
  17. Bugleweed (Ajuga spp.) zone 3-9
  18. California poppy (Eschscholzia californica) annual
  19. Candytuft (Iberis spp.) zones 3-8
  20. Carnation (Dianthus spp.) zones 3-8
  21. Catmint (Nepeta spp.) zones 3-8
  22. Cleome (Cleome spp.) annual
  23. Columbine (Aquilegia spp.) zones 3-10
  24. Conifers (most species) zones 2-10
  25. Coreopsis (Coreopsis spp.) zones 3-10
  26. Cosmos (Cosmos spp.) annual
  27. Crocosmia (Crocosmia spp.) zones 5-11
  28. Cyclamen (Cyclamen spp.) zones 5-9
  29. Daylily (Hemerocallis spp.) zones 3-9
  30. Epimedium (Epimedium spp.) zones 3-9
  31. Euphorbia (Euphorbia spp.) zones 1-12
  32. Fennel (Foeniculum vulgare) zones 6-9
  33. Ferns (most species) zones 1-12
  34. Foxglove (Digitalis spp.) zones 4-9
  35. Fuchsia (Fuchsia spp.) annual or zones 7-9
  36. Gazania (Gazania spp.) annual
  37. Geranium, hardy (Geranium spp.) zones 2-10
  38. Ginger, hardy (Hedychium spp.) zones 7-12
  39. Globe thistle (Echinops spp.) zones 3-9
  40. Goat’s beard (Aruncus app.) zones 3-8
  41. Grasses, ornamental (most species) zones 2-12
  42. Hellebore (Helleborus) zones 4-8
  43. Heuchera (Heuchera spp.) zones 3-9
  44. Holly, sea (Eryngium spp.) zones 3-9
  45. Hosta (Hosta spp.) (thick-leaved and blue-leaved varieties) zones 3-9
  46. Houseleek (Sempervivum spp.) zones 3-10
  47. Hydrangea (Hydrangea spp.) zones 3-9
  48. Impatiens (Impatiens spp.) annual
  49. Ivy (Hedera spp.) zones 5-10
  50. Jacob’s Ladder (Polemonium spp.) zones 3-8
  51. Knautia (Knautia spp.) zones 3-8
  52. Lady’s mantle (Alchemilla spp.) zones 3-9
  53. Lantana (Lantana spp.) zones 9-12
  54. Lavender (Lavandula spp.) zones 5-10
  55. Lettuce, romaine (Lactuca sativa) vegetable
  56. Lily of the Nile (Agapanthus spp.) zones 8-11
  57. Lobelia, edging (Lobelia erinus) annuelle
  58. Lungwort (Pulmonaria) zones 3-9
  59. Marigold, pot (Calendula officinalis) annual
  60. Masterwort (Astrantia spp.) zones 3-9
  61. Meadow rue (Thalictrum spp.) zones 3-8
  62. Mint (Mentha spp.) zones 2-10
  63. Mock Strawberry (Duchesnea indica) zones 4-9
  64. Monk’s hood (Aconitum spp.) zones 3-9
  65. Mullein (Verbascum spp.) zones 3-8
  66. Nasturtium (Tropaeolum spp.) annual
  67. Nemesia (Nemesia spp.) annual
  68. Nicotiana (Nicotiana spp.) annual
  69. Oregano (Origanum vulgare) zones 4-10
  70. Pelargonium (Pelargonium spp.) zones 9-12
  71. Penstemon (Penstemon spp.) zones 3-9
  72. Peony (Paeonia spp.) zones 3-9
  73. Periwinkle (Vinca spp.) zones 4-10
  74. Phlox (Phlox spp.) zones 2-9
  75. Pincushion flower (Scabiosa spp.) zones 3-8
  76. Pink (Dianthus spp.) zones 3-8
  77. Poppy (Papaver spp.) zones 3-8
  78. Portulaca (Portulaca spp.) annual
  79. Potentilla (Potentilla spp.) zones 3-9
  80. Rhododendron (Rhododendron spp.) zones 3-10
  81. Rockcress (Arabis spp. and Aubretia spp.) zones 3-5
  82. Rodgersia (Rodgersia spp.) zones 4-9
  83. Rose (Rosa spp.) zones 2-10
  84. Rosemary (Rosmarinus officinalis) zones 8-10
  85. Rudbeckia (Rudbeckia spp.) zones 3-8
  86. Sage (Salvia spp.) zones 5-9
  87. Salal (Gaultheria shallon) zones 6-8
  88. Saxifrage (Saxifraga) zones 3-9
  89. Sedum (Sedum spp.) zones 2-12
  90. Snapdragon (Antirrhinum majus) annual
  91. Snow-in-summer (Cerastium spp.) zones 3-8
  92. Speedwell (Veronica spp.) zones 3-9
  93. Thrift (Armeria spp.) zones 3-9
  94. Thyme (Thymus spp.) zones 3-9
  95. Tulip (Tulipa spp.) zones 3-8
  96. Verbena (Verbena spp.) annual
  97. Violet (Viola spp.) zones 2-10
  98. Yew (Taxus spp.) zones 4-7
  99. Yucca (Yucca spp.) zones 3-12
  100. Woodruff, sweet (Galium odoratum) zones 3-9Zinnia (Zinnia spp.) annual

Slug-Susceptible Plants

Most herbs are quite slug resistant… but not basil (Ocimum basilicum). You can use it as a trap plant to draw slugs away from other herbs and vegetables. Photo: ask.extension.org

The following plants are very subject to slug damage, especially in humid climates or when grown in shade or under moist conditions. They may actually attract slugs to your garden and increase the local slug population resulting in damage to normally less susceptible plants.

Note that many vegetables are susceptible to slug damage as seedlings, but then are left alone when they mature. In fact, one way of reducing slug damage in seriously slug-infested vegetable gardens is to consistently start seedlings indoors and only plant them out after their leaves have hardened.

  1. Basil (Ocimum basilicum) zones 10-11
  2. Bean (Phaseolum spp., Vicia spp. and Vigna spp.) vegetable
  3. Begonias, tuberous (Begonia x tuberhybrida) zones 10-12
  4. Cabbage (Brassica oleracea) vegetable
  5. Canna (Zantedeschia spp.) zones 8-12
  6. Coleus (Plectranthus scutellarioides) annual
  7. Corn (Zea mays) vegetable (seedlings only)
  8. Dahlia (Dahlia spp.) zones 8-12
  9. Delphinium (Delphinium spp.) zones 3-9
  10. Hosta (Hosta spp.) (thin-leaved varieties) zones 3-9
  11. Lettuce, leaf, crisphead and Boston (Lactuca sativa) vegetable
  12. Ligularia (Ligularia sp.) zones 3-9
  13. Lily-of-the-valley (Convallaria majus) zones 2-7
  14. Marigolds (Tagetes spp.) annual
  15. Mustard (Brassica spp.) vegetable, herb
  16. Potato (Solanum tuberosum) vegetable (some varieties are slug resistant)
  17. Primrose (Primula spp.) zones 3-9
  18. Seedlings of most vegetables
  19. Soybean (Glycine max) vegetable
  20. Strawberry (Fragaria spp.) zones 3-9

Article originally published on July 17, 2015.

Slug Resistant Plants

Standard

20150717C

Some plants simply send slugs running!

The true secret to controlling slugs easily is not to battle them with egg shell barriers, beer traps, or other lures, repellents or snares, but to remove the plants that attract them and to replace them with plants that don’t.

The classic case is of course the hosta.

20150717A

Hosta undulata ‘Albomarginata’ attracts slugs like a magnet.

Hostas are renowned for attracting slugs. Yet in fact, only some hostas are to blame. In fact, three hostas – by far the most popular in our gardens – are the main victims of slug damage: Hosta ‘Undulata Albomarginata’, a medium-size hosta with fairly narrow wavy-edged leaves edged in white, H. ‘Undulata Mediovariegata’, similar, but with a reverse variegation (there is a flame-shaped white marking in center of the leaf) and H. ‘Undulata Univittata’, again with the same wavy fairly narrow leaves, but this time entirely dark green, with no variegation. These are the hostas used for mass plantings, grown by millions in temperate climates around the world, largely because they grow and multiply quickly, making them inexpensive. But they also attract slugs like a magnet.

Slugs actually hide in the roots and crowns of these hostas at night. They also lay their eggs at the base of H. ‘Undulata Albomarginata’, H. ‘Undulata Mediovariegata’, and H. ‘Undulata Univittata’ and young slugs get their start feeding on their leaves. Just removing these hostas from your garden can so reduce the slug population in general that even other slug-susceptible plants are largely left alone.

20150717B

Thick-leaved Hosta ‘Sum and Substance’ is an example of a hosta that seems totally resistant to slugs.

But not all hostas attract slugs. Many are only somewhat attractive to slugs and only suffer minor damage, especially early in the season. And some hostas are out and out slug-resistant. This is the case of many if not most of the modern varieties, since hybridizers selectively breed for slug resistance, but many old-fashioned hostas are slug-resistant as well. H. sieboldiana ‘Elegans’, for example, a well-known and highly slug-resistant hosta, was introduced in 1905! Slugs are not attracted to thick-leaved hostas, nor hostas with blue leaves, for example.

Other Plants

You can almost tell if a plant will attract or repulse slugs just by studying it. Slugs tend to prefer plants with soft, thin leaves. That’s why they do so much damage to seedlings: young plants’ leaves have not yet developed their more leathery final texture. Conversely, slugs tend to avoid leaves that are hairy, tough, fibrous, thick or waxy, as well as those with a bitter taste or with strong odors (many herbs are slug resistant, for example). Oddly, slugs often find plants that are poisonous to humans quite palatable.

Slug-Resistant Plant List

20150717D

Daylilies (Hemerocallis) are almost never attacked by slugs.

Here is a short list of slug-resistant plants. I’ve included mostly perennials, annuals, herbs and vegetables. Most shrubs, conifers and trees, even if they may be somewhat susceptible to slug damage in their youth, eventually outgrow the damage.

  1. Ageratum (Ageratum houstonianum) annual
  2. Alyssum, sweet (Lobularia spp.) annual
  3. Anemone, Japanese (Anemone x hybrida, A. japonica, A. hupehensis)
  4. Artemisia (Artemisia spp.) zones 2-9
  5. Astilbe (Astilbe spp.) zones 4-8
  6. Bachelor’s buttons (Centaurea cyanus) annual
  7. Bamboo (most species) zones 4-11
  8. Bamboo, heavenly (Nandina domestica) zones 6-10
  9. Basket of gold (Aurinia spp.) zones 3-9
  10. Begonia, bedding (Begonia semperflorens) annual
  11. Bellfower (Campanula spp.) zones 3-7
  12. Bergenia (Bergenia spp.) zones 3-9
  13. Bidens (Bidens spp.) annual
  14. Black-eyed Susan (Rudbeckia spp.) zones 3-8
  15. Bleeding heart (Dicentra spp.) zones 3-9
  16. Bluestar (Amsonia spp.) zones 3-9
  17. Bugleweed (Ajuga spp.) zone 3-9
  18. California poppy (Eschscholzia californica) annual
  19. Candytuft (Iberis spp.) zones 3-8
  20. Carnation (Dianthus spp.) zones 3-8
  21. Catmint (Nepeta spp.) zones 3-8
  22. Cleome (Cleome spp.) annual
  23. Columbine (Aquilegia spp.) zones 3-10
  24. Conifers (most species) zones 2-10
  25. Coreopsis (Coreopsis spp.) zones 3-10
  26. Cosmos (Cosmos spp.) annual
  27. Crocosmia (Crocosmia spp.) zones 5-11
  28. Cyclamen (Cyclamen spp.) zones 5-9
  29. Daylily (Hemerocallis spp.) zones 3-9
  30. Epimedium (Epimedium spp.) zones 3-9
  31. Euphorbia (Euphorbia spp.) zones 1-12
  32. Fennel (Foeniculum vulgare) zones 6-9
  33. Ferns (most species) zones 1-12
  34. Foxglove (Digitalis spp.) zones 4-9
  35. Fuchsia (Fuchsia spp.) annual or zones 7-9
  36. Gazania (Gazania spp.) annual
  37. Geranium, hardy (Geranium spp.) zones 2-10
  38. Ginger, hardy (Hedychium spp.) zones 7-12
  39. Globe thistle (Echinops spp.) zones 3-9
  40. Goat’s beard (Aruncus app.) zones 3-8
  41. Grasses, ornamental (most species) zones 2-12
  42. Hellebore (Helleborus) zones 4-8
  43. Heuchera (Heuchera spp.) zones 3-9
  44. Holly, sea (Eryngium spp.) zones 3-9
  45. Hosta (Hosta spp.) (thick-leaved and blue-leaved varieties) zones 3-9
  46. Houseleek (Sempervivum spp.) zones 3-10
  47. Hydrangea (Hydrangea spp.) zones 3-9
  48. Impatiens (Impatiens spp.) annual
  49. Ivy (Hedera spp.) zones 5-10
  50. Jacob’s Ladder (Polemonium spp.) zones 3-8
  51. Knautia (Knautia spp.) zones 3-8
  52. Lady’s mantle (Alchemilla spp.) zones 3-9
  53. Lantana (Lantana spp.) zones 9-12
  54. Lavender (Lavandula spp.) zones 5-10
  55. Lettuce, romaine (Lactuca sativa) vegetable
  56. Lily of the Nile (Agapanthus spp.) zones 8-11
  57. Lobelia, edging (Lobelia erinus) annuelle
  58. Lungwort (Pulmonaria) zones 3-9
  59. Marigold, pot (Calendula officinalis) annual
  60. Masterwort (Astrantia spp.) zones 3-9
  61. Meadow rue (Thalictrum spp.) zones 3-8
  62. Mint (Mentha spp.) zones 2-10
  63. Mock Strawberry (Duchesnea indica) zones 4-9
  64. Monk’s hood (Aconitum spp.) zones 3-9
  65. Mullein (Verbascum spp.) zones 3-8
  66. Nasturtium (Tropaeolum spp.) annual
  67. Nemesia (Nemesia spp.) annual
  68. Nicotiana (Nicotiana spp.) annual
  69. Oregano (Origanum vulgare) zones 4-10
  70. Pelargonium (Pelargonium spp.) zones 9-12
  71. Penstemon (Penstemon spp.) zones 3-9
  72. Peony (Paeonia spp.) zones 3-9
  73. Periwinkle (Vinca spp.) zones 4-10
  74. Phlox (Phlox spp.) zones 2-9
  75. Pincushion flower (Scabiosa spp.) zones 3-8
  76. Pink (Dianthus spp.) zones 3-8
  77. Poppy (Papaver spp.) zones 3-8
  78. Portulaca (Portulaca spp.) annual
  79. Potentilla (Potentilla spp.) zones 3-9
  80. Rhododendron (Rhododendron spp.) zones 3-10
  81. Rockcress (Arabis spp. and Aubretia spp.) zones 3-5
  82. Rodgersia (Rodgersia spp.) zones 4-9
  83. Rose (Rosa spp.) zones 2-10
  84. Rosemary (Rosmarinus officinalis) zones 8-10
  85. Rudbeckia (Rudbeckia spp.) zones 3-8
  86. Sage (Salvia spp.) zones 5-9
  87. Salal (Gaultheria shallon) zones 6-8
  88. Saxifrage (Saxifraga) zones 3-9
  89. Sedum (Sedum spp.) zones 2-12
  90. Snapdragon (Antirrhinum majus) annual
  91. Snow-in-summer (Cerastium spp.) zones 3-8
  92. Speedwell (Veronica spp.) zones 3-9
  93. Thrift (Armeria spp.) zones 3-9
  94. Thyme (Thymus spp.) zones 3-9
  95. Tulip (Tulipa spp.) zones 3-8
  96. Verbena (Verbena spp.) annual
  97. Violet (Viola spp.) zones 2-10
  98. Yew (Taxus spp.) zones 4-7
  99. Yucca (Yucca spp.) zones 3-12
  100. Woodruff, sweet (Galium odoratum) zones 3-9Zinnia (Zinnia spp.) annual

Slug-Susceptible Plants

20150717E

Most herbs are quite slug resistant… but not basil (Ocimum basilicum). You can use it as a trap plant to draw slugs away from other herbs and vegetables.

The following plants are very subject to slug damage, especially in humid climates or when grown in shade or under moist conditions. They may actually attract slugs to your garden and increase the local slug population resulting in damage to normally less susceptible plants.

Note that many vegetables are susceptible to slug damage as seedlings, but then are left alone when they mature. In fact, one way of reducing slug damage in seriously slug-infested vegetable gardens is to consistently start seedlings indoors and only plant them out after their leaves have hardened.

  1. Basil (Ocimum basilicum) zones 10-11
  2. Bean (Phaseolum spp., Vicia spp. and Vigna spp.) vegetable
  3. Begonias, tuberous (Begonia x tuberhybrida) zones 10-12
  4. Cabbage (Brassica oleracea) vegetable
  5. Canna (Zantedeschia spp.) zones 8-12
  6. Coleus (Plectranthus scutellarioides) annual
  7. Corn (Zea mays) vegetable (seedlings only)
  8. Dahlia (Dahlia spp.) zones 8-12
  9. Delphinium (Delphinium spp.) zones 3-9
  10. Hosta (Hosta spp.) (thin-leaved varieties) zones 3-9
  11. Lettuce, leaf, crisphead and Boston (Lactuca sativa) vegetable
  12. Ligularia (Ligularia sp.) zones 3-9
  13. Lily-of-the-valley (Convallaria majus) zones 2-7
  14. Marigolds (Tagetes spp.) annual
  15. Mustard (Brassica spp.) vegetable, herb
  16. Potato (Solanum tuberosum) vegetable (some varieties are slug resistant)
  17. Primrose (Primula spp.) zones 3-9
  18. Seedlings of most vegetables
  19. Soybean (Glycine max) vegetable
  20. Strawberry (Fragaria spp.) zones 3-9 (fruit only)

Slug Treatments that Really Work!

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20150716IOver the last two days, I presented two slug treatments of varying effectiveness. The eggshell barrier treatment does not work at all. The beer slug trap does work to a certain extent, but is not very effective. Here are other treatments against slugs along with an assessment of their effectiveness.

Diatomaceous Earth

20150716ATreatment: Surround the plant with a circle of diatomaceous earth (a white powder derived from fossilized algae).

Effective: Slugs seems to hate diatomaceous earth and will avoid crossing a barrier made of it unless very hungry. The theory I keep hearing is the sharp particles of diatomaceous cut the slug’s delicate skin, leading to its death. This is nonsense, of course. First, slugs have a very tough epidermis, not easily scratched, and secondly, they give off a slimy mucus to allow them to travel over the roughest, sharpest surfaces, so ought to be able to travel readily over diatomaceous earth. The proof of the pudding is that, if they are forced to cross diatomaceous earth, slugs are in no way damaged by their passage. The real reason they avoid this product remains a mystery… but they do!

Downside: The barrier must be replaced each time it rains.

Wood Ashes

Treatment: Surround the plant with a circle of wood ashes.

Effective: Again, slugs have so far refused to answer questions as to why they avoid wood ashes, so it is not known if they avoid them because they are so alkaline (pH of 10 to 12!), whether they don’t like their texture, or if some other factor is involved. Whatever the reason, slugs don’t seem to appreciate them,

Downside: The barrier must be replaced after each rain. Also, if you apply too many ashes too often they can render the soil too alkaline for most plants.

Coffee grounds

Treatment: Surround the plant with a circle of coffee grounds.

Ineffective: Slugs will cross a barrier of coffee grounds barrier as it if weren’t there. Totally ineffective.

Copper Barrier

20150716BTreatment: Surround the plant with copper tape or netting. You can also fix copper tape or netting to the sides of pots or raised beds to prevent slugs from climbing up.

Effective: It is often said that slugs receive a small electric shock when they touch a copper barrier. Whether that’s true or if some other factor is the cause is not known, but it has been clearly demonstrated that slugs will generally avoid crossing a copper barrier.

Downsides: Copper in any form can be quite expensive. Also, when it rains, copper barriers placed on the ground are often partially covered in soil, in which case the slugs will not hesitate to cross them.

Slug Bait Containing Metaldehyde

Treatment: apply pellets containing metaldehyde to the ground or pour them into a trap with openings only large enough for slugs.

Effective: Slugs eat the poison and die.

Downsides: Product not recommended! This product is highly toxic to pets and wildlife and even (to a lesser extent) to children. Most suppliers add Bitrex to their pellets, a very bitter product that slugs don’t notice, but that mammals quickly spit out, thus reducing the risk of accidental poisoning. Birds, however, generally ignore Bitrex, so can still be poisoned. If this product is used, it’s best to place this type of bait in a trap or under a length of board, away from curious animals. Even though this product is still available, few experts now recommend it for domestic use. It has been widely replaced by slug bait containing iron phosphate (described immediately below). Other caveat, granules exposed to rain decompose and have to be replaced.

Slug Bait Containing Iron

20150716CTreatment: apply pellets containing iron phosphate or sodium ferric EDTA (iron in a sodium EDTA chelate) to the ground or pour them into a trap with openings only large enough for slugs.

Effective: When slugs eat iron, they stop eating immediately, then die of dehydration three to six days later. The two products mentioned as effective with slugs as metaldehyde baits, but are non-toxic to other animals (mammals, birds, fish, insects, microbes, etc.). Moreover, they also act as fertilizers to a certain degree. Both seem to be accepted in organic gardening.

Downsides: The granules decompose when exposed to rain. Suggestion: place them under a board or an inverted bowl to protect them from the elements. Also, if you apply iron-rich year after year in the same place, excess iron can build up in the soil and that will have negative effects on plant growth.

Watering in the Morning

20150716HTreatment: water plants in the morning rather than late afternoon or evening.

Effective: The damage by slugs is greatly reduced when plants are watered in the morning rather than late in the afternoon or in the evening: often by up to 80%! Why? When you water in the evening, the soil remains damp all night and slugs, who are most active at night, just love moist conditions. By watering in the morning though, when slugs are not active, your plants will receive the water they need, but the soil has time to dry out before nightfall and that discourages slugs. Note too that watering in the evening also tends to also increase plant diseases. Avoid watering plants in the evening and you’ll help solve both problems.

Household Ammonia

20150716JTreatment: Spray or water affected plants with a solution of 1 part household ammonia (NH₃) to 6 parts water. Repeat weekly as needed.

Effective: Ammonia is toxic to slugs, but little else in the garden, at least not when properly diluted (it’s very alkaline and, at full strength, may burn the foliage of delicate plants). It’s also a good source of nitrogen for plant growth. This treatment seems most effective on young slugs when they hatch in the spring.

Table Salt

20150716KTreatment: sprinkle ordinary table salt on slugs

Somewhat effective: Even a grain or two of salt causes slugs to start to dehydrate. Apply just a bit more and they will be killed. However…

Downside: Salt is hard to apply, as slugs are not always out in the open on a flat surface where you can reach them with a salt shaker. And you have to apply it directly to the pest, whereas most slugs are pretty much hidden from view. Finally and even more importantly, salt is toxic to plants too and it is almost impossible to apply so it only touches the slugs. Most of it ends up on the ground, contaminating the soil.

Hand picking

20150716D

You’re allowed to wear gloves while hand picking.

Treatment: Harvest  slugs in the morning or after a rain… even at night with a flashlight.

Effective to somewhat effective: To make slugs easier to find, leave a piece of board, a half grapefruit or an inverted clay pot on the ground: slugs readily hide in the shade near their favorite plants during the day, so you can just lift the “trap” and collect them. When they’re in hand, deposit them in soapy water or use any other method you desire to dispatch them.

Downside: The effectiveness of this method largely depends on your conditions. If slugs are very localized, hand-picking can seriously reduce the population. If there are slugs everywhere, you won’t likely make much of a dint in the population.

Ducks

20150716ETreatment: release the ducks in the garden, especially early morning when slugs are still active.

Effective: ducks are very attracted to slugs, seeming to prefer them over almost anything else. In Germany you can actually rent ducks for slug control.

Downside: Ducks pull up and eat young seedlings and can also crush plants by accident. It is best to keep them out of the garden in the spring until the plants are well established. Or, release them at the end of winter, before planting, to clean up before planting starts.

Encourage Slug Predators

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Ground beetles, often seen in our gardens, are major slug predators.

Treatment: Create an environment that is conducive to slug predators.

Effective: Provide an environment for wildlife, including hiding places, a bit of water, a wide range of plants, and varied environments to encourage slug predators such as snakes, frogs, toads, fireflies, beetles, birds and shrews. And above all, learn to tolerate the presence of these predators. You don’t have to hug a garter snake or kiss a frog: just learn to let them be.

Downside: Some slug predators are less desirable in the garden, among them raccoons and skunks.

Slug-Resistant Plants

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Hostas with thick leaves repel slugs.

Treatment: Replace the plants subject to slug damage by species that slugs dislike.

Top tip! This truly solves the slug problem once and for all! Once you get rid of slug magnets like thin-leaved hostas and leaf lettuce, the slug population will start to drop. And since the few slugs that remain are no longer eating your plants (because they don’t like the plants you’re now growing), but instead actively help to decompose dead vegetation, which is theoretically their true role in nature, do you even care if they’re still there? After all, detritus-eating slugs are no longer your enemies, but now your friends!

This is the number one slug control method for truly laidback gardeners, the secret to gardening in harmony with a former enemy. Sometimes gardening is so simple!

Here is a list of slug-resistant plants… and also a list of plants that you should avoid: the ones that attract slugs to the garden.