White Spots on Tomato Leaves

“I have been having problems with my tomatoes.  They have white blotches on the leaves.  What is wrong with them?  Thanks, Genevieve”


Hi Genevieve,

Thank you for giving us a call in regards to your tomato transplants.

Based on the description I was given (white patches on leaves), it sounds like your tomatoes got a little bit too much sun.  Just like humans, green leaf tissue can get sunburned.  When you have transplants that have been grown indoors or in a greenhouse, putting them outside in the sun right away is like putting a baby out in the sun with no sunblock.  Instead of turning red like a lobster, the UV rays in the sun kills the chlorophyll in the cell and damages the internal cellular structures that create more chlorophyll.  Without pigmentation, the cell becomes colorless.  When you have multiple cells in an area do this, the leaf takes on a white look.

Depending on how damaged your plants are, there is a chance they will survive.  The next steps you need to take are as follows:

1.     Allow your plants to just stay indoors for a couple of days.  They have been stressed, so you don’t want to continue this.  Baby them a little bit by making sure that they are in their ‘normal’ (prior to going outdoors) setting.  If they have been grown in a greenhouse, there is no need to worry about the light in there because the plastic or glass that is used in the walls deflects the UV rays.

2.    Before the plants go out into the full sun, they need to be hardened off.  On a day with little to no wind, set them outside in the shade of a tree.  For 2 days, use a tree that has very little light filtering through (like an evergreen).  Then for a few more days after that, use a tree that has lots of filtered sunshine (like a deciduous tree).  Keep the transplants in at least some degree of shading with a little more light each day for about one week.  Maintain normal watering practices during the day.  Pick them up at night so that they aren’t dinner for a passing animal and bring them in if there is cool weather or frost forecast.

3.    Once the plants have been hardened off, they are ready to be out in the full sun.  The plants can be grown in their containers in the sun until they are ready to be transplanted or put right into the soil if the weather is warm enough in your part of the country.

I hope this information helps you out.  If you have any other questions, please feel free to ask.

Have a great day!




© Mertie Mae Botanics LLC and Horticulture Talk!, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Mertie Mae Botanics LLC and Horticulture Talk! with appropriate and specific direction to the original content.


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