Hosta FAQs: What can go wrong?

While there are lots of places online to find information about hostas (see our links), and of course a number of books you can buy for ready references, we didn't feel that there was a good place online for FAQs (Frequently Asked Questions), as experience with the American Hosta Society's Facebook page has shown. We hope you find this useful. The good stuff is at Part I. Here are FAQs on hosta problems. You may also want to check the "Hosta Health" part of the Lingo page.

Click on the little ˅ at the end of each line to expand (and then collapse) the answers.

Hail hit my hostas! What do I do?

Oh hail no! A hailstorm can be devastating to the appearance of a hosta garden, but fortunately the plants will survive. In general, resist the temptation to cut off all the foliage, although in severe circumstances (and early in the season) that may be the best answer. Any foliage still attached is still feeding the plant, as awful as it might look. Now is the time that they will need a good dose of fertilizer; they will respond by making new leaves. As the new leaves come in, consider again whether you want to cut off the tattered ones. And remember that next year will probably be better.

My hostas got bigger the first two years but are now getting smaller. What’s wrong?

The answer is almost certainly tree root competition. You made a lovely home for your hostas under shade trees, but the trees found that space a really good place to send roots. Some trees, like red maples (Acer rubrum) are particularly notorious for strangling hostas. Others (including black walnuts) are not nearly as bad. Some gardeners resort to growing most of their hostas in pots rather than in the ground, but that’s an extreme solution. One simpler solution is to space your hostas out a bit more so that once or twice a year you can, with a sharp shovel (and being mindful of spreading HVX), cut a ring around each hosta to sever the roots growing into it. One bad solution is to pile a foot of soil all the way around a tree (even worse, using some barrier cloth), which can smother the tree.

How do I keep deer from eating my hostas?

Deer are smart, and deer are stupid. You have to train them that your garden is off-limits. The obvious solution is a fence, six to eight feet tall. Large dogs can also help. But if that’s not practical (and for most of us, it isn’t), you need be vigilant and use a cycle of products that make the hostas unpalatable. Train them that your hostas are "off limits" all season long. Early in the season you may want to start with Milorganite, which is "recycled" from sewage (that is, predator poop). It also serves as a good spring fertilizer. Then when the hostas leaf out you'll likely need to switch to sprays. Most of the sprays include rotten egg solids, garlic, and/or hot pepper. Some use a bit of this but also use oils like rosemary and mint that deer simply don’t like. Spray the hostas every week or two in the spring, especially after rain. It can help to switch the spray from brand to brand from time to time. The classic “Irish Spring soap in a stocking” trick doesn’t work so well for hostas, as you have to get it right where the deer noses go. Blood meal and coyote urine may also help, but the sprays are generally going to give the best results. Note that at the end of the season, when you’re likely to be lazy and the deer are fattening up for winter, they may eat your hostas anyway. Don't worry, the hostas will come back.

How do I keep rabbits from eating my hostas?

Your hostas may never be bothered with rabbits (they like to eat other stuff in our garden), but you may want to try a spray based on hot pepper (use caution), or spread some moth flakes (naphthalene) around plants they’re bothering. Note that where deer eat the leaves and leave the petioles behind, rabbits will cut off the petioles at the base and eat their way up to the leaves. Groundhogs, if you have a problem with them, will eat it all (but usually not that many). Rabbits are also fond of bloom scapes (before or after flowering), so hybridizers beware! Mice may eat seed pods, but generally nothing else. (Voles are a different problem.)

How do I keep slugs from eating my hostas?

The gray garden slug (classic slug of the eastern US, not the leopard slug, which has spots) is a serious pest for hostas. There are several ways to control them. One is a commercial “pellet” poison based either on a chelated iron phosphate (not as animal-friendly as the product claims to be) or on metaldehyde (harder to find now, and not very animal-friendly either). If you have animals that like to eat out of your garden, the toxicity of these product can be of concern, especially if you spread the product too thickly. Spread thinly and you’re not likely to have any collateral damage to animal life. The current version of "Bug-geta" uses ground sulfur instead, but I don't know how effective it is. Another control method is to spray into and around the plants with a diluted ammonia solution. This can kill slug eggs as well, but the solution has to contact the slugs and/or eggs directly. Try spraying at night when they’re active. A third classic control is to set shallow dishes filled with beer into the ground. Slugs crawl in and drown, and you pick them out the next day (ewww). A similar treatment is to simply put tender lettuce on the ground at night and pick up the slug-covered leaves early the next morning (still alive, of course). Some people claim that orange and grapefruit peels have a similar attractive effect and might even kill them. Stories of repelling or killing slugs with coffee grounds, egg shells, grapefruit rinds, and the like are simply wives' tales. They are not a serious way to address a serious problem. Note that the leopard slug (the big one with obvious dark spots) is not your enemy. It only eats decaying plant matter (stuff on the ground) and as a bonus, eats the eggs of other slugs! Unfortunately it’s very challenging to kill off the bad slugs and leave the good ones around, unless you use the night-time seek and spray method above. Another pest that makes damage similar to the pinholes from slugs is the flea beetle. These little pests can swoop in, damage a few or a lot of hostas in one area, and then disappear over the period of a few days. This makes them very hard to manage.

How do I keep voles from eating my hostas?

Voles (not moles, which are carnivorous insect-eaters) can cause rapid and serious damage by eating the hosta roots right up into the crown of the plant. The evidence is divisions that weaken and even fall over, and pull away from the plant with no roots. You may find the little tunnels, just underground (or under your mulch) where the little guys are moving around. You have three options: spray your property with castor oil to repel them, poison “bait” stations to eradicate them, or barriers around your hostas to keep them away from the crowns. (Having an outdoor cat can be a helpful third option.) For barriers you can create collars using hardware cloth. These should go into the ground about 5" and stick above the ground/mulch by 1". They should be big enough around so that most hosta roots will stay inside. An alternative to this is to buy inexpensive wire wastebaskets, dig a hole and plant the basket with 1" above ground, and plant the hosta in the basket. You can use a good spray paint to paint the rim of the basket to camouflage it.

How do I keep nematodes from eating my hostas?

Foliar nematodes (not to be confused with beneficial nematodes that are sometimes used to treat problems with grubs, etc.) are microscopic worms that invade the hosta leaves and leave brown streaks on infested leaves, weakening the plants and making the leaves unattractive. The nematodes can move about in the soil to get to other plants, or ride along on drops of water where one plant touches another. Unfortunately there is not a ready treatment for these pests. An extreme treatment is to heat-treat the hosta by getting the crown up to about 110 °F, but this usually kills off the leaves for the season and the plant will come back smaller next year. Be sure to kill off any nematodes in the hole where you dug up the hosta with lots of boiling water. One preventive treatment which may significantly reduce the nematode population is to pour that boiling water on the crown of each hosta in early spring, before the pips begin to emerge from the crown. Hard work for sure. A product called NemaStop is promoted by its makers (and has been tested by scientific research with good results) as an effective treatment, but again timing of the application of the treatment solution is tricky, as you need to get the nematodes while at a vulnerable stage in early spring. If you're interested in more information on this, use the Contact form. One way to minimize the problem of nematodes is, if you have an infested plant, pull off the worst of the leaves. Minimize contact between plants. And gather up all leaves in fall before they can rot into the ground, sending them to landfill rather than putting them in your compost pile. Note that there is a bacterial infection that can cause symptoms that mimic the between-the-veins streaking of foliar nematodes. This can usually be distinguished by having a water-logged rather than a desiccated (dried out) appearance of the streaked portion

What about HVX (the dreaded Hosta Virus X)?

That's a topic that deserves its own page, Part IIa.

Have I got rot?

See the Lingo page (under Hosta Health) for a description of the serious rotting diseases, which may be caused by fungus or bacteria.

Dew you know

what to dew?

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