The Best Slug-Proof Plants
Considering how small they are, slugs can do an awful lot of damage in a garden. While you can address this issue by putting down baits, repellents, etc., perhaps the best way to solve the problem is to grow plants that slugs do not eat (or that they eat less often, at least). Always remember, too, that a stray hole here or there will have little impact on plant health or garden beauty. It is often best, therefore, to overlook such damage, rather than trying to replace your favorite specimens with less desirable ones that happen to be more resistant to these pests.
The plants that slugs eat the most are typically those with leaves that are thin and soft. Hosta plants, for example, are well-known magnets for slugs; think of them as "slug lettuce." By contrast, it is often safer to grow plants with leaves that have unappealing-looking textures. For example, these slimy pests tend to leave alone leaves that are rigid, that bear a waxy coating, or that are bristling with tiny hairs. Also more resistant are those that give off strong smells or that are bitter-tasting.
Slugs especially like to eat seedlings and the new leaves on plants. If there's nothing else leafed out at the time that they like better, they may make exceptions to their usual diets. They'll eat the new leaves of some supposedly slug-resistant perennials and annuals. Much more thoroughly slug-proof are most of the woody plants (such as shrubs) and ornamental grasses.
Slugs and their relatives with shells, the snails, are both gastropods (and mollusks). They leave behind a trail of shiny slime and big holes in the leaves of plants that they eat. They are most active where the ground is damp and the temperatures cool.
Wormwood (Artemisia spp.) is an example of a plant that slugs don't care to eat. Silver Mound wormwood (Artemisia schmidtiana Silver Mound) is the ultimate outdoor foliage plant, sporting wonderful, silvery leaves and a compact form. Use it to edge a walkway or any area where you are seeking low-maintenance landscaping. Powis Castle is a type that gets taller. The added height makes it less useful as an edging plant, but a better choice if you want to harvest the fragrant foliage for making wreaths. It may well be the strong smell of its leaves that makes it slug-resistant.
Columbine plants (Aquilegia) are extraordinarily lovely, especially if you crave flowers that have a lot of character. In profile, the shape has been compared both to a dove and to a bird of prey, which accounts for the common name and botanical name, respectively. A full-face shot reveals a flower within a flower. Another plus for this perennial is that the flowers come in a variety of colors. The clover-like leaves are also nice. While slugs do not eat them very often, leaf miners do cause damage to the leaves.
What is it about Jacob's ladder (Polemonium) that discourages slugs from munching on it? Who knows? Maybe they can't get a good toehold on the rungs of its ladder-like leaflets (the presence of which account for the plant's common name). Regardless, you will value this slug-resistant perennial for its tolerance for dappled shade and its blue, purple, or lavender flowers.
Euphorbia plants such as purple wood spurge contain a milky sap that makes them poisonous plants. This sap renders them bitter-tasting, thereby sending Mr. Slug scurrying for tastier fare. Other types of spurge include:
- Cushion spurge (E. polychroma)
- Cypress spurge (E. cyparissias)
- Mediterranean spurge (E. characias)
Slugs do not like to eat ferns. Maybe that's why ferns have been around for so long. There are many kinds of these ancient plants, such as the interrupted fern (Osmunda claytoniana). Their slug-resistance is reason enough for many gardeners to forgive them for not bearing flowers. Other common types of ferns include:
- Christmas fern (Polystichum acrostichoides)
- Cinnamon fern (Osmundastrum cinnamomeum)
- Japanese painted fern (Athyrium niponicum)
- Maidenhair fern (Adiantum spp.)
As with most plants, the seedlings of tree peonies (Paeonia suffruticosa) will have to be protected from slugs. But slugs generally leave the mature plants alone, other than putting the occasional hole into a leaf here and there (which does no real harm).
Slugs would not bother eating the rigid, fibrous leaves of the various kinds of Yucca, such as Adam's needle (Yucca filamentosa), even if the plants' texture were the only reason to leave them alone. But it is not the only reason. The pests do not like the taste of it. No wonder that an extract from this shrub (commonly treated as if it were a perennial) is sold as a slug repellent.
Catmint plants (Nepeta spp.) have a strong smell, which is probably why slugs do not like them. Many herbs are strong-smelling, and slugs usually leave them alone. Larger types, such as Six Hills Giant, make for effective ground covers.
Slugs probably have two reasons for not wanting to eat the leaves of Lenten rose (Helleborus orientalis):
- They have a waxy coating.
- They are quite tough (which is why they hold up so well season-to-season in the garden).
The hairy leaves of lamb's ears (Stachys byzantina) make them slug-resistant. They may repel slugs, but you will be drawn to them. Gardeners can't resist petting lamb's ears as they walk by while doing their gardening chores. S. byzantina is one of the few plants that you will ever grow mainly for the way it feels.