Tomato Leaves Turning White – Causes & Treatment
Are the leaves of your tomato plants turning white and they are drying out? This post will explain the causes, what to do to save your plants and what you can do in the future to avoid this problem.
This was the first year when I decided to plant my own tomato seedlings instead of buying them.
I planted the tomato seeds in January and I moved them in my greenhouse at the beginning of April.
The weather was a bit unpredictable. There were days when the outside temperature went over 20-degree Celsius and other days when it dropped to less than 10 degrees.
The tomato seedlings grew nicely since I kept them in a heated hallway that has many windows. Therefore, there’s was plenty of light reaching out to the plants.
Everything was great until I transplanted the tomato seedlings into the greenhouse.
The first two days, the plants looked very good and had no signs of transplanting stress.
The next days, the leaves of some tomato plants started to turn white and the edges of the leaves started to dry out.
I really had no clue why.
At first, I thought the plants are lacking magnesium, but the leaves seemed to be more white than yellow as in the case of magnesium deficiency.
I used my friend Internet to search for an answer and after reading several articles, I concluded that my plants were affected by sunscald.
Since this was the first time I grew my own tomato seedlings, I didn’t know that the plants can be hit by sunscald if I move the plants directly from indoor to the greenhouse.
Even though the seedlings had a lot of light in the hallway where they were placed initially, the sun rays didn’t really reach the plant leaves directly.
Fortunately, there were several cloudy days after I transplanted the seedlings and the sun wasn’t really that strong. That might have just saved my plants from drying up completely.
Common Causes Why Tomato Leaves Turn White
Here are several interesting facts I found related or similar to my problem.
If the leaves of your plants are turning white, this is usually caused by:
- Exposure to intense sunlight (sunscald)
- Overwatering your plants
- Too much fertilizer
- An acute deficiency of nutrients (calcium, nitrogen, phosphorus, etc.)
- A fungal disease
Last year, my tomato plants faced a fungal disease called early blight (you can read more about that here). However, the symptoms were a bit different.
Tomato Sunscald Treatment
Sunscald is not a plant disease, but more a sunburn that affects plants.
I can probably say that sunscald is more of a plant sensitivity to the UV rays and intense light.
Sunscald doesn’t only occur on tomatoes. It can also affect peppers, cucumbers, corn leaves, trees leaves and their fruits, eggplants, pumpkins, strawberries, and so on.
Unfortunately, since sunscald is not a disease, there’s no treatment for it. In fact, the best treatment for sunscald is prevention.
If your plants have been affected heavily, there aren’t many things you can do to save them.
Still, if the tomato plant stem and the growing tips are still green, the plant has a good chance to rebound.
Watch the short video below to make a better idea of how my seedlings looked like after their leaves started to turn white.
The affected leaves will eventually die off and fell down.
If your tomato plants are big enough, you can even speed up this process by removing the affected leaves since these won’t regenerate.
In my case, the sunscald affected my tomato seedlings after I transplanted them from an indoor environment where the plants were safe from direct sunlight, to a greenhouse where the sun rays reached the plant leaves directly.
Even though seedlings are more predisposed to be hit by sunscald, it seems like the full-grown plants can also be affected.
In the case of an adult plant, sunscald will usually affect the fruits of the plant. When these grow in lower light and suddenly are exposed to higher light levels, these can easily be affected by sunscald.
For example, a pumpkin that grows most of the time covered by the leaves of the plant.
How To Prevent Seedlings Sunscald
My mistake was that I didn’t give my tomato seedlings any time to adapt to direct sunlight.
More exactly, if you keep your seedlings in an environment where the sunlight doesn’t hit the plants directly, you have to gradually expose the plants to direct light.
Therefore, before you transplant your seedlings to a greenhouse or directly in your outside garden, take your plants outside for several hours per day to harden them.
Leave your plants in the sun for about 1-2 hours the first day, then increase the sun exposure gradually for at least 7 days before you transplant the plants.
When you feel like your plant is ready to handle a full day of sun, your seedlings are ready to be moved to your greenhouse or garden.
Conclusion
Just as babies, plant seedlings are sensitive and more predisposed to various diseases.
When you grow your seedlings in a closed environment, the plants’ immune mechanisms are weaker.
Therefore, to avoid issues like sunscald, the plants need to be hardened off and gradually adapted to natural conditions like full sunlight and wind before you permanently transplant them to your garden or greenhouse.
Unfortunately, I didn’t know this before I transplanted my tomato seedlings and my poor plants had to suffer the consequences.
I’m still learning from mistakes and I will avoid this issue the next year.
Update: Fortunately, all my tomato seedlings have fully recovered after sunscald, even though I was really skeptical that the plants would survive.
It took about two weeks until the plants started to grow new green leaves since the transplanting.
I also gave them a little boost with a bit of fertilizer since my garden soil is not very nutrient-rich.
Thank you so very much! This is my 1st time growing anything & Im doing if from seed! Ive already lost my lettuce, most of my carrots, & a few pepper plants 🙁 I think those got fungus flies though. Growing food is definitely more challenging than I thought!
Hi
I just had the same thing happen to me. I didn’t harden off the seedlings and one of them has sun scalding on its leaves. I also removed a lot of leaves when I planted it, so to remove the ones that are scalded would leave the plant leafless. The stem is still green. I guess I’ll just try to shade it with SOMETHING ( not prepared for this sort of thing so I don’t have screens or special items to shade it with ) and hope for the best. Should I give it a boost of fertilizer like a 5-10-5 just to push out some new growth? Wish there was a plant doctor out there who made house calls!!!!
Hi Kim,
If the stem is still green, the plant should recover. Fortunately, all my tomato seedlings recovered after sunscald, even though most of them were affected in a high percentage at first.
I also added a bit of fertilizer to give the plants a boost since the soil I moved the plants in is a bit sandy.
I have to admit that the weather also helped a bit since there were several rainy days after the leaves of my plants started to turn white.
At first, I only removed the affected leaves for the plants that had more leaves. I removed all the leaves affected by sunscald after new green and healthy ones grew.
Hi Crystal,
Indeed, gardening, even if it sounds simple, has some secrets and there are certain rules to follow if you want your plants to thrive.
Besides problems like sunscald, there are also various weeds, diseases and pests that you’ll have to fight with.
Thanks for this article, done heaps of Googling and not got anywhere! Till now anyway. My seedlings are only 4 weeks old or so and they seem to be quite affected after all the hot weather we had.
Would you recommend feeding them with fertiliser at this early stage of life?
And – would you mind providing a bit more detail on how you hardened them off? I have a lot of small plants inside and this is the most challenging thing for me at the moment!
Thanks again
Hi Nathan,
Sorry to hear that your seedlings were affected by sunscald.
Unfortunately, I don’t think fertilizer will help since your plants are only 4 weeks old. If you’ve initially planted them in good growing soil, they should still have all the needed nutrients.
The only way to harden the plants is to gradually take them out for several hours a day. Start by placing them in semi-shade, and slowly expose them to more direct sunlight each day.
I’d say that you should repeat the process for at least 7 days before transplanting the plants.
Unfortunately, I don’t think there is another remedy for plants that were already affected by sunscald.
Even though my tomato plants were affected to a considerable degree, fortunately, all have managed to recover completely last year. I have to admit though that I was quite skeptical at first.
I put out my four big boy tomato plants, two days later the leaves are mostly white. I was so proud of my work, put some tomato tone mixed into the dirt when I planted them now the leaves are mostly white. I attempted to harden them off, guess I didn’t do it long enough.
I have just finished reading Nathan’s response of his attempt and your reply.I am so glad to find out I cannot fix it ,will just wait for some new growth and then cut off the bad parts.
Anna Brown, I think you for your site and the answer to my problem I don’t think I would have started all over. THANKS AGAIN
Hi OLD YARD WORKER,
Sorry to hear that your plants have been affected by sunscald. I hope they will all recover as mine did.
Indeed, unfortunately, all you can do is to wait for new growth and then remove the affected leaves.
Don’t panic though if that takes 2 or 3 weeks before you see the occurrence of the new foliage. That’s about how much it took in my case.
All the best!
I have 6 plants with white spots. Your tomato pictures look exactly like mine. I was worried that it might be fungus an all the rest would be affected. Thank you for this information. I will try to save my tomato plants as you suggested
You’re very welcome, Mary. I’m glad you found my article helpful.
Glad I found your site and glad to hear it’s likely most my tomatoes will make it! I grew the majority from seed this year for the first time and only one variety of those seems affected, despite hardening off. I also bought some from a greenhouse and two of those heirloom varieties are struggling a bit too. We’ll wait and see!
I had 250 tomatoe plants and through 60% away with the sun scald. I will now try and save the rest now that they now have it to . Wish Me luck!!
Hi Brian,
All my plants managed to survive that year, so I hope your tomatoes will do the same.
Thank you for this post.
This year I “rushed” my hardening off and my tomatoes (& peppers) that were such hardy seedlings are all part white from sun scald.
I hope they recover.
I was taking such good care of them & I actually feel sad that I harmed them.
Last year I did hardening gradually & no problems.
Guess this year I learned what hardening off really does.
Hi Rachel,
I know exactly the feeling. I hope your seedlings will recover and produce a good crop.