Why are my Hosta leaves going brown on the edges?
Brown leaf edges are common on Hostas, as well as some other shade loving plants, when the temperatures rise or the sun is too intense.
Brown leaf edges, known as scorch, occur when the plant loses more water than is available or faster than the plant can absorb. It will start with the outer leaves. They become brown and scorched, and if left unchanged will affect the rest of the plant.
Hostas with white or pale cream centres are more susceptible to leaf scorch. Without any chlorophyll, they are more easily burnt. This will take place from the middle, white bit, rather than the darker margins. They take less sun to burn than green or blue Hostas.
Sometimes, even in this country, we get extremes of sun & heat, even for short periods, and even this can be harmful to Hostas.
So, how do we reduce the risk of environmental damage to our precious Hostas?
Reduce the risk of this problem by growing your Hostas in an environment recommended position for Hostas, like shady areas, of dappled shade, but more importantly, free of hot mid-day sun.
Try to ensure that your Hostas are watered well. This must be done before any heat or hot sun appears. This gives your Hostas at least some moisture to compensate any loss of moisture through the leaves. Water the plants thoroughly and often enough to keep the soil slightly moist. If they have enough moisture to draw up, there is less chance of damage from the sun.
Do not, I repeat, do not water when the sun gets up. Try water either early morning or late evening. Watering in full sun will scorch your Hostas leaves, as the moisture on the leaf dries quickly, and draws out moisture from the leaf.
Improve the water-holding ability, by adding a thick layer of organic matter, or mulch. You can use any kind of mulch you have on hand.
Mulch the soil with shredded leaves, evergreen needles or other organic matter to keep the soil cool and evenly moist. Yes, I know, this also creates the perfect environment for slugs. If a slug problem develops, deal with them as you normally would. See my blog on slugs & snails. https://www.rewelahostas.com/post/ways-to-protect-your-hostas-from-slugs-and-snails
My preferred mulch, although it is a little more expensive, is bark. These little critters do not particularly like sliding on this material, therefore reducing any slug infestation.
So, what do you do with these sun damaged plants?
It’s not the end of the world! Your Hostas will recover.
If you are unlucky enough to find multiple scorched leaves on your Hosta, the best thing to do is to remove the damaged leaves and compost them. If you leave them on the plant, you will be encouraging a massive influx of slugs & snails. They are attracted to the smell of damaged and dying leaves. So get rid of them. Do not leave the effected foliage on the ground.
Once the Hostas are clear of damaged foliage it is important to ensure they are watered, but not In full sun.
If you left it a bit long before removing the damaged leaves, you may find more need to be removed and the remaining Hosta will look a lot more de-nuded.
It will recover, provided that it is given adequate shade cover
If your Hostas are being scorched regularly, then they may be in the wrong place.
A permanent solution is to consider digging them up and putting them somewhere more suitable. Before you move them, ensure they are well watered before being lifted, maybe a day or so earlier, and also, well watered, when re-planted. Maintain the care in the first year, just as you would when planting a new specimen.
If you are unable to remove and plant elsewhere, or don’t want to, you can opt for a s more temporary solution, which is to provide some shade for them where they are now. This can be done easily with items such as patio umbrellas, or some netting above your Hostas, to provide shade. This could be done in conjunction with planting a small tree or shrub, to eventually grow and give shade for later years.
Overall, try and put your Hostas in a suitably shaded environment and the chance of sun or heat scorch is drastically reduced and keep them moist. They love it!
Just a quick footnote :- Maybe it’s a disease?
Is it possibly Anthracnose? This is characterised by irregularly shaped white to tan spots with a brown border. The spots often lose their centres and the leaves become tattered and torn. The disease thrives in warm, wet conditions, so maintaining good plant spacing is important for prevention.
To be absolutely certain, if you think the Hosta has Anthracnose, the tools used for leaf removal should be thoroughly disinfected and the foliage burnt. Do not put these leaves on the compost.
Apply a fungicide labelled for ornamental plants.
Anthracnose is not widespread and should not be confused with heat stress or sun scorch of leaves. It is far less likely than anything else that bother the Hostas.
To learn more about Hostas, you may interested in reading : AI Generated Hosta Photographs, Watering and Feeding Your Hostas, What Are the Common Mistakes to Avoid When Growing Hostas?, Ways to Protect Your Hostas from Slugs and Snails and "Uncovering the Advantages of Bare Root Hostas:
Shop for Hostas HERE
John Plant
Rewela Hostas
Thank you for the blog John,another very informative post,Good idea with the netting.