Hostas are suited to areas of the garden where other plants won’t grow. They also produce purple fragrant flowers. There can be some issues that can occur with the leaves of hostas so today I will explain how to remedy a hosta that is having leaf issues.
Underwatering, too much sun, soil that isn’t free draining, and not enough nutrients cause hosta leaves to curl. To return the hosta to normal keep the soil moist, replant them in a more shaded spot, and into free draining soil with the right pH.
Pests insects can be irradicated with neem oil or insecticide. Based on how the leaves are curling will give you a clear indication of what is likely causing the issue. For example, if they’re curling up it indicates that they are getting too much sun or wind.
I’ll explain the different ways the leaves will curl and what this indicates, as well as, what to do based on each of the different reasons why your hosta leaves are curling.
Not enough water causes leaves to curl under
As you may know, hostas are some of the most water-loving plants. They can be watered almost as much as you like. Because of this, they are suited to boggy areas of the garden. But, if they’re a bit too dry the leaves will curl from the sides underneath themselves. The stems of the leaves will also bend more and the plant will appear to be drooping.
This is a clear sign they aren’t getting enough water. Interestingly, once you water them within about 5 minutes the leaves will return back to normal and the stems will straighten up.
- Water your hostas immediately.
- Water them enough so the soil is always damp – you don’t need to be concerned about overwatering.
- Do not allow the soil to be bone dry for very long.
Too much sunlight or wind exposure causes leave to curl upwards
Leaves of plants have a protective mechanism where their leaves will curl up at the edges and provide shelter for the top of the leaves. This occurs in response to too much sunlight or wind. Hostas are shade tolerant and unlike some other plants do not need much sun at all. And do well in a bright area without direct sun. However, some sunlight throughout the day is ok too.
- Replant your hostas in an area where they get less direct sun and less wind.
- Move potted hostas to a more shaded and less windy spot.
Poor draining soil
Free draining soil allows the water to get down into the deep roots. The pH of the soil also controls what nutrients are available to be taken up by your hostas. For example, if the soil is more acidic there will be more of some nutrients that are free to be absorbed and less of others.
The pH of the soil can be tested using a low-cost pH soil testing kit with you can buy from a garden supply store or online. The ideal consistency of the soil is loose like that of a standard potting mix. Clayey compacted soil is too thick and will starve hostas of nutrients. This causes yellow spotting on the leaves and also causes them to curl.
- Replant them in loose free-draining soil.
- If the soil pH is too high add sulfur to lower it.
- If the soil is too low add lime which are products made from crushed limestone.
Various pests will feed on the stems and leaves of hostas. They sometimes go undetected because they are small but over time as they sap small amounts of nutrients the leaves will begin to curl. If these pest insects are left untreated they can eventually kill the leaves.
Scale is easily identifiable as you will see bumps on the stems, which are the bodies of these bugs. Mealybugs produce white silk on the underside of the leaves and also have a characteristic white fluffy body.
Some pest insects are ok. But when their numbers get out of control they can damage the leaves and cause brown spots, yellow spots. Over time the leaves will turn brown, go crispy, and then fall off. There is also a range of fungi that can grow on the leaves. Luckily the method to treat all of these causes is exactly the same – neem oil.
- Spray neem oil onto the affected areas after sunset.
- Isopropyl alcohol also called methylated spirits can be dabbed onto the insects using a cotton bud.
The climate is too hot or too cold
Hostas do best in USDA hardiness zones 3 through 8. This is pretty much the entire USA except for the very south of the southernmost states. And the extreme north of the middle northern states. California is also much too hot for most varieties of hostas.
While many varieties won’t do well in very hot climates such as those outside of zones 3 to 8, lately there have been many heat-tolerant varieties being selectively bred. This produces a hosta that can withstand extreme heat and extreme cold.
There’s a possibility the variety of hostas you have aren’t suited to your specific climate. There’s no easy way around seeing if this is the issue. You’ll need to identify what variety of hostas you have, and look up what hardiness zones it grows best in.
- Replant new hosta varieties that are heat or cold tolerant.
- Replant less heat-tolerant varieties in a heavily shaded spot.
- Bring potted hostas indoors or to a very sheltered place when it gets very cold.
Hostas are very greedy for nutrients. Unlike many other plants, they can take a lot of fertilizer and not suffer root damage. If the soil is a bit nutrient-poor the leaves will develop yellow spots, curl, and can develop wrinkles.
Experienced hosta growers recommend Miracle-Gro which is very inexpensive. As well as, a special fertilizer called milorganite. Milorganite is made from human waste which also deters deer and rabbits. They smell the human scent and sense danger. This causes them to stay away and not feast on your hostas.
- Feed your hostas with Miracle-Gro and/or milorganite once a month.
- Replant them into more nutrient-rich soil that has the consistency of the potting mix.