If you’re a hosta-lover or a gardener with lots of hostas, then white spots on your hosta leaves are something you don’t want to take lightly. Hostas are known to withstand dry weather and are pretty shade-tolerant. So what would cause them to turn white?
Hosta leaves turning white could be due to prolonged drought, plant infection like anthracnose, or various conditions such as sunscald or iron chlorosis. When your hostas lose their lush green color, that’s a sign that they’re making less or no chlorophyll.
Understanding the causes and how to prevent and manage hostas when they turn white will place you in control of your plants. Therefore, in this article, we’ll take a closer look at why hosta leaves turn white, discuss the effects of the various conditions, and explore the remedies available.
Hosta leaves turn white because they lack chlorophyll, the green pigment on plant leaves. This whitening may also be due to exposure to excessive sunshine or fungal or viral infection or signify a lack of nutrients and minerals such as iron.
Here are the causative conditions we’ll look at:
- Leaf scorch
- Iron chlorosis.
Anthracnose refers to a group of fungal infections that cause dark spots on leaves. In severe cases, these infections cause recessed blemishes and wilts on branches and stems. The fungi that cause anthracnose thrive in wet conditions.
The specific conditions promoting the occurrence of anthracnose-causing fungi include:
- Overhead irrigation
- Warm Conditions
To protect your hostas from anthracnose infestation, apply this simple multi-pronged strategy. Start by irrigating your hostas in the early morning. This action will hydrate them and allow the afternoon heat room to evaporate the resulting dampness.
Another effective way of protecting your hostas from anthracnose is keeping them cool. Plant your hostas strategically under garden trees or deck shades. In the absence of such sun shields, you can erect your shade with the following:
- Patio umbrellas
Also, once you spot an anthracnose infestation on your hostas, remove the infected leaves to prevent the fungi from spreading further.
If anthracnose has been a problem in your garden before, applying a fungicide is advisable even before the condition manifests.
The effectiveness and number of sprays will depend on the weather and fungicide brand you use.
Hostas acquire viral infections through unsterilized tools, propagating infected hosta plants, and feeding insects. Research findings also show that seeds, sprouts, and seedlings inherit viral infections.
There are multiple viruses known to impede normal hosta cell growth, causing their leaves to turn white. However, the most common virus types affecting hostas include:
- Hosta virus X
- Arabis Mosaic
- Tomato ringspot virus
- Impatiens necrotic spot virus.
Since various hosta cultivars are in the market, it’s easy to take an infected hosta for a unique pick. That some healthy hosta varieties share physical attributes such as leaf puckering and odd leaf form increases the intrigue of identifying a healthy hosta.
Therefore, thoroughly familiarizing yourself with the hosta you are purchasing will help you avoid the virulent plant.
No known chemical can cure a plant infected by a virus. Unfortunately, once attacked, your hosta will eventually die. Similarly, resistant plants will not show the expected growth response, despite your devoted care.
To protect your hosta plants from viral infection:
- Minimize physical contact between cultivars when tending plantings.
- Disinfect tools shared between plants and cultivars to divide hostas and remove leaves.
- Remove any contaminated plants showing symptoms or testing positive for the virus.
- Reintroduce plants that have been virus-tested and verified to be virus-free.
Besides viruses, pests such as slugs irritate your hostas. To repel them, create a ring with a tablespoon of Epsom salt once a week around your hostas.
Hostas thrive under shaded spaces; therefore, too much direct sunlight causes sunscald. They only benefit from the gentle morning and evening sun.
Too much sunlight degrades chlorophyll, the green pigment in plant leaves. Since your hostas can’t replace chlorophyll as quickly as they’re losing, their leaves turn cream or white. Excessive sunlight coupled with inorganic soil makes the leaves papery white and dry, eventually falling off.
Hostas thrive in USDA Hardiness zones 3-8, including warmer states such as Texas, California, and Arizona. However, it would help if you took care in the more generous zones so that you may protect your hostas from excess sunlight in the summer months.
Give your hostas temporary relief in dry weather by watering them in the morning. However, transplanting them to a shaded location is the permanent solution. If you can’t move them, create a shade above them, as discussed above.
Additionally, increase soil organic matter. You can use Charlie’s Compost (available on Amazon.com) for this purpose. It’s mixed with several natural organic materials and thoroughly composted, so it doesn’t have a strong foul odor. This compost will increase the soil’s nutrients, making your hostas healthier.
As for damaged leaves, you cannot restore them. You may leave them on the hosta because the remaining green portion remains useful. But if you find them unsightly, remove them.
Leaf scorch is more about water movement through the hosta plant than infection or sunburn. So, please don’t mistake it for a hosta disease. To be sure, it’s critical to consider the weather when assessing plant problems.
Although a slightly scorched leaf will not kill the hosta, it’ll not recover either. Nevertheless, resist the urge to remove the affected leaf. Leaf scorch isn’t an infection and therefore poses no danger to the rest of the hosta or its neighbors.
As unpleasant as it may look, the remaining green tissue remains active in chlorophyll production, enabling new foliage growth. Besides, it’s giving the new growth some protection from the sun. Eventually, if the scorched leaves haven’t fallen off naturally, you can gently remove them once new leaves have developed.
Other environmental influences can cause leaf scorch, such as:
- Hot temperature
- High winds
- Low soil moisture.
These conditions cause your hosta to lose more water than it can replace in good time. An acute water shortage will cause cell damage, resulting in a white tan.
To protect your hostas from sunscald and leaf scorch, minimize their exposure to severe sunlight and water loss. It’s vital to give your hostas enough water, especially on sweltering and windy days.
Here are specific actions you can take to prevent sunscald and leaf scorch:
- Organic mulching: Regulates soil temperature around the hosta roots and conserves soil moisture.
- Sufficient watering: You should water weekly enough to wet the soil to its maximum depth and a diameter of at least 2 feet (24 inches).
- Early transplanting: Moving hosta seedlings to a shady and moist place reduces their chances of sunscald and leaf scorch.
- Commercial formulations: During the rapid development period of hostas, mix two teaspoons of Epsom salt (8.4 grams) in 1 gallon (4.5 liters) of water with a liquid plant fertilizer like Bonide Liquid Plant Food (available on Amazon.com). Sprinkle this mixture on the plant once a month or according to the manufacturer’s instructions.
Iron chlorosis is a deficiency in a plant’s mineral iron (Fe). You can identify this condition by yellowing or whitening the hosta leaves. Interveinal chlorosis causes the leaves to develop dark green veins as the rest of the surface pales away.
As in all hosta leaves turning white, iron deficiency prevents chlorophyll formation, reducing hosta growth and vigor. Iron chlorosis may affect a portion of a hosta or its entirety. The affected part may die and fall off in severe or prolonged cases.
The cause of iron chlorosis on your hostas may be one or a combination of the following factors:
- Soil alkalinity: Limey and with a soil PH higher than 7.0 causes chemical reactions unfavorable for the liquefaction of solid iron at the roots of your hostas.
- Restricted air circulation: This issue is due to water saturation, compaction, and plastic sheet mulching.
- Topsoil removal: Erosion or leveling can occur due to housing or other construction projects’ bare lime-saturate soil.
The first step towards iron chlorosis prevention is planting hosta cultivars that tolerate high soil PH and are less likely to be stunted by low iron availability.
Regulate water content by reducing watering or installing drainage and aerate regions near the base of affected hostas. Also, avoid mulching your hostas with plastic sheeting since it hinders oxygen movement into the soil.
You may treat your plant for iron insufficiency in two ways, namely:
- Soil treatment: A combination of inorganic iron (ferrous) Sulfate Heptahydrate and fertilizer acid mix can provide long-term results at a low cost. An inorganic iron like Alpha Chemicals Ferrous Sulfate Heptahydrate (available on Amazon.com) is excellent as it’s very soluble, easy to prepare and use, and contains 20% iron. Down to Earth Acid Mix Fertilizer (also on Amazon.com) is a good option for fertilizer acid mix as it’s all-natural.
- Foliar treatment: Spray a 0.5 percent solution made by dissolving 2 ounces (57 grams) of ferrous sulfate (20 to 22 percent iron) in 3 gallons (13.6 liters) of water regularly.
It’s possible to prevent your hostas’ leaves from turning white. Avoid conditions that might cause chlorophyll depletion. For example, plant your hostas away from direct noonday sunshine. Allow only the morning and evening sun to reach them.
Irrigate your hostas moderately and early in the morning during dry and windy periods. And since most of these conditions cause similar symptoms, it’s advisable to conduct various diagnoses whenever in doubt.
Finally, read the manufacturer’s instructions carefully whenever you use commercial formulations to supplement or treat your hostas.
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Hi! I’m Sophia, and I love plants – especially an expert in growing house plants. I stay in Chicago, United States of America, and through my blog and social media platforms, provide tips and tricks on how to grow healthy, vibrant plants indoors. Check out more here.