What Causes Hosta Leaves to Curl? Can it Be Fixed?
Are you seeing curling leaves on your hosta? This is actually quite commnon, and can happen for a number of different reasons. The good news is, many times, it's completely correctable. In this article, certified master gardener and gardening expert Laura Elsner takes a look at the different reasons this happens, and how to fix it.
Hostas are a beautiful foliage plant that thrive in shady conditions and are fairly fuss free and unproblematic. However, like with all plants, they can never be 100% problem free.
The leaves of a hosta curling up is usually a sign that something is wrong. I wish I could just tell you “it’s this” and then tell you to “do that” and it will magically go away. Of course, it is never that simple. You will have to be a bit of a plant detective and start examining the curled leaf hosta and its environment to start ruling things out and exploring possible problems.
This article aims to help you identify the possible problems so you can get to the bottom of why your hosta’s leaves are curling.
There are over 3000 registered varieties of hostas, they vary in size, leaf shape, and color. This is to say that not all hosta varieties are the same. I’m bringing this up so we can rule out one cause of leaf curl in hostas before we dive in any further. Some hostas varieties have curled leaves.
Some varieties have natural ruffled leaves, Hosta ‘Dancing Queen’ for example has beautiful chartreuse leaves with wavy crinkly edges. If this hosta was next to a Hosta ‘Sum and Substance’ which has large chartreuse, even round edges you would notice the curling of Dancing Queen’s leaves immediately.
Hosta ‘Abiqua Drinking Gourd’ is another different hosta variety with leaves that are curled up into little cups. This is also normal. So take a look at your hosta and try to figure out the variety and determine if the leaves are meant to be ruffled or curled.
Another cause of leaf curl that is directly related to the variety is what is known as the drawstring effect in hostas. This occurs in varies that have light colored margins and darker centers (eg. Hosta ‘Patriot’).
Since the inner portion of the hosta has more chlorophyll and produces energy faster than the colorless white margin, the inner leaf is growing fast and will push the edges up resulting in a cupping effect.
The only thing that can really be done about this is avoiding certain varieties of hostas that are prone to this, or keeping those hostas in less sunlight in order to slow the growth rate of the entire plant. This isn’t a super common problem, so do not rule out other possible causes before landing on this one.
All plants have a set of ideal growing conditions, these are usually the conditions to where a plant is native to and has evolved to grow. Hostas are native to parts of China, Japan, and Korea. They can be found growing in forested areas, along river banks and near water.
This means they like to be kept moist, they like the rich humus soil found in the forest, and they grow on the forest floor with a canopy of trees protecting them from the sun and wind. This is all very important to understanding your hostas needs, it is best to try and mimic these conditions in your garden for growing hostas.
Hostas grow naturally in woodland areas, these areas have a constant turn over in tree and plant matter that makes for really light humus (full of organic matter) soil. This is what you want to create in your garden.
This will be easier for some people than others. I live in a region where my soil is dense clay. I can hold a handful of my unamended soil and squeeze it into a ball and it will stay in that ball shape. Hostas don’t like that dense soil on their roots.
If I planted a hosta straight into that soil the leaves would curl under and start to turn yellow. The soil once squeezed in my hands should just crumble away and not hold its shape. That is good hosta soil. So if your hosta has curling leaves and is planted in really dense clay soil, this could be your problem. Now what? Amend the soil.
Dense clay soil will need something light and fluffy to offset it. Peat moss used to be my go to for making my clay soil more workable, and it is still widely available and works. However, I made the switch to coconut coir whenever possible as it is a renewable resource, where peat moss is not. Either way work this light fluffy peat or coir into the soil to lighten it. Now that the soil is not so heavy we still need to add nutrients into the soil, as peat moss and coconut coir don’t have much for nutrients.
In nature, hostas grow on the forest floor where plants and animals are all living and dying and cycling through, everything goes back to the earth and creates lush soil. To do this in our own gardens we will need to add it in.
Use compost (your own or purchased), worm castings, sea soil, or aged manure to top dress the light fluffy peat and topsoil that are already in the garden. I don’t till the compost layer in, I just top dress the beds with it and then water it in so all the nutrients seep down into the soil. I top dress the beds either in early spring, or late fall.
Additional Soil Tips
There is a shortcut to all of this if you’d prefer, you can purchase a soil blend called triple mix that is a combination of topsoil, peat, and compost. I prefer to do it on my own to get the ratios just as I need them, but this is a good time saver.
In containers, use potting soil, not soil from the garden. In an enclosed pot, water needs to be able to drain easily, and garden soil is just too heavy to allow for this in containers.
Now that the soil is light, fluffy, rich and free draining your hosta is now in its ideal soil conditions, if this is what was causing the leaf curl it should be corrected. Of course this won’t happen magically overnight, give the hosta time, perhaps even a season, to recover.
This is probably one of the more common causes of curling leaves on your hostas. Lack of water will cause the leaves on a hosta to droop down and curl inwards. When I see this I always think the plant looks sad. This is a sign to water more, especially if the leaves perk back up when they get a good drink.
So this leads to the question about how much water is enough water, unfortunately there is never a straight forward answer to this question. I mean it’s confusing enough on houseplants where you control all the watering, but in the garden there is rain water too that will have to be factored into watering.
If your garden has irrigation, great, you probably don’t have curling leaves from lack of water, but just to be sure, go check the soil around the hosta/s with curling leaves and make sure the irrigation is hitting the hosta, sometimes spots can be missed and the system just needs to be adjusted.
For the rest of us, watering just has to become part of a gardener’s routine. I use a drip hose and snake it through my hosta garden and then I will turn it on about once a week, depending on rain, and let it run slowly for an hour or two (it’s a really slow drip).
If I notice on a hot day that my hostas are drooping I will turn on the drip hose. This way I don’t spray the foliage in the heat of the day. If you are using a spray nozzle hose, only water hostas when they are in the shady part of the day, watering them when they are in the sun can burn their leaves.
Watering For New Plants
Newly planted hostas will need more water than an established (has gone through 2+ seasons) one. I would double the amount of water on a newly planted hosta for the first month or two and then keep an eye on it to make sure it is getting enough after that.
Watering is connected to the soil. Make sure you have amended the soil so that it is light, fluffy, and rich, this way when you are watering the soil will be able to retain the water it needs for the roots, and drain away any extra water that it does not need. If your soil has a crusty, cracked appearance on its surface it is likely not absorbing enough water, add peat/coir and compost.
Mimicking Hostas in Nature
Hostas in their natural environment live surrounded by other plants, if you notice in the woods there is something growing out of every space. All the combined roots act like a net to hold on to moisture. Mother Nature is not a minimalist, and I love her aesthetic.
I like keeping gardens full by layering them with plants, an over story of trees, shrubs, and large perennials, then an understory of perennials (this is where hostas fit) and then below that a creeping layer of ground cover that acts as natural mulch. Lysimachia (Creeping Jenny) or vinca vine are great choices for ground covers around hostas that will contrast against their foliage nicely and help retain moisture.
If neat and tidy is more your style, every plant in its place sort of method (I find this a common look that hardscape landscape companies design), then consider adding mulch to the beds to hold in moisture.
For hostas grown in containers, daily watering could be necessary since they tend to dry out faster, I would check it daily or every second day, you’ll soon figure out the routine your hosta needs for water in a pot.
Now for a less common reason your hosta leaves could be curling, and that is over watering. Hostas like moisture, it’s hard to over water them if the soil is able to drain. But they do not like being in standing water or boggy conditions, this will lead to root rot which could include curling of the leaves, then yellowing, then rotting, and then death.
If your hosta is in soggy conditions you might consider adding peat/coir to absorb the extra moisture, or you may have to move the hosta out of the boggy area completely.
It all begins with the soil, then we added the water, now it’s time to look at the sunlight. Hostas are known as shade perennials, they do not like the harsh rays of the hot afternoon sun. But different varieties of hosta can tolerate various light conditions.
Any of the darker green, or dusky blue tinged hostas need more shade than the bright chartreuse colored ones.
Curled and crisp edges on hostas are a sign they are getting too much sun. Although, if the hosta is in more sun and the leaves are curled and not crisp, try watering more often. Hostas will tolerate more sun if they are getting enough water.
If you’ve noticed burnt and crispy curled edges, and extra water doesn’t help (or it’s too much work keeping up on the watering) take note of how much afternoon sun they are receiving. Ideally, I would say no more than a few hours of sunshine a day, but this depends on where you live (Seattle sun is not as harsh as Arizona sun). If it is getting too much sun, it might be time to transplant your hosta to an area with more shade.
Going back to the native growing conditions of hostas, they prefer the rich humus soil that is provided on the forest floor. However, some of our garden and top soil is depleted of nutrients, this will cause hosta leaves to curl since they do not have access to the nutrients they need to thrive.
The best way to add nutrients back to the soil is to amend the soil (read the soil section of this article), adding compost or some form of rich organic matter (worm casting, sea soil etc.) early in the season. This will provide the hosta with all its nutrient needs. As far as fertilizer goes, I do like to boost my soil with a naturally derived fish fertilizer or compost tea. This will help boost all the microbes and create beautifully healthy and alive soil that is the most conducive for growing hostas.
Fertilizer can be used. If this is the route you want to go, choose an even 10-10-10 all purpose fertilizer and make sure to only fertilize after watering. Over fertilizing and fertilizing dry plants can result in burned crispy curled leaves (which is just the problem we are trying to solve!). Read the package direction and follow, more is not better.
Going back to hostas native growing conditions, they are low lying plants that receive a lot of protection from trees and shrubs that grow above them. This is important to note once we bring them into our garden, they like to be protected from the elements.
In our gardens protection might be near the house, or under a garden bed with a large tree (this is great for sun protection as well), or a fenced in backyard in a neighborhood. The point is, they do not tolerate winds blasting them constantly, this will cause their leaves to curl.
If you notice curled leaves, and the soil seems fine, watering seems fine, the sun seems fine, take a look at the location. If it is windy and the leaves are constantly blowing around, this could very well be the problem. The hosta should be moved to an area with more protection.
I always start with environmental problems when it comes to problems with plants. Now that all the possible environmental causes have been looked into, and none of those reasons (soil, water, sun, fertilizer, wind) seem to be why your hostas leaves are curled, it is time to consider pests.
Sap sucking pests such as aphids, thrips, and mealy bugs can infest a hosta and suck their leaves until they start to curl. Check the stems and the nooks in the leaves to find these insects on the hosta. The good news is that if you have your hostas growing in their ideal conditions they are less likely to be infested with pests.
Never underestimate a good blast with the hose to rid a hosta of aphids, but if the infestation is really bad consider spraying the hosta with an insecticidal soap (one containing neem oil). Apply this in the morning or evening, not in the heat of the day, and apply weekly (or according to the directions) until the cycle is broken and the pests are gone.
Gardeners aim to tame nature and cultivate it for themselves, but at the end of the day it’s the plants that we must serve. Keeping a plant in its ideal growing conditions as nature intended is the best way to ensure that it thrives. Hostas are no exception, keep them growing in their ideal and natural conditions and they should not have problems and live in your garden for years.
Curling leaves is a sign something is not right with its growing conditions and once you can narrow down what the problem is, you can identify and correct it and enjoy that lush foliage once again.