Sunburn damage on cucumber seedling

So I transplanted my super healthy looking cucumber seedling outside thinking they had grown enough to survive outdoors. What I didn’t take into consideration was that plants could also get a sunburn. NM State describes this really well but basically this is what’s going on: When you start your plant (in my case cucumbers) indoors from a seed they grow what you may call “shade leaves” which are developed under low light. These leaves don’t have full protection from direct sun light.

In the photo above on the left you can see my cucumber plant was developing white spots around the edges, took a light green color, and was almost crispy to touch only two days after it was transplanted outdoors. To avoid getting your seedlings sun burnt you need to gradually expose them to outdoor conditions. Maybe start with only two hours of direct sunlight a day and over a period of week or two increase this period until they’re fully ready for those strong UV rays from the sun. This is called hardening off.

After you’ve made the mistake I’ve made and transplanted your seedlings outdoors without hardening them off there’s no going back. Your seedling will lose those sun burnt leaves. Now you hope that you’re seedling is still healthy enough to produce brand new sun leaves. During this difficult transition period your plant will need less water since you killed all those poor indoor leaves. But do increase watering as the new leaves start coming out.

On the right hand side above you can see my plant managed to recover from its sun burn and got its healthy dark color back with plenty of new leaves.

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3 Responses to Sunburn damage on cucumber seedling

  1. Andrew Lim January 9, 2014 at 9:46 am #

    Hello there,
    I’ve been trying to grow Japanese cucumber and okra in pots but the seedlings’ growth seems stunted whenever I repot them from peat pods into bigger soil filled pots.
    Can you please advise on the proper time to repot these seedlings?
    I’m from Malaysia. Tropical weather all year long.
    Thanks for your advise and help.

    • Helen June 18, 2016 at 6:34 pm #

      I am from central Texas where we get lots of rain at the beginning of Spring, but then before Summer technically arrives we often times go into drought season. Right now the temperatures are in the 90’s but with a humidity factor of feeling like 105! I can’t imagine how hotter it probably gets in Malaysia! My point is that if I have to plant my garden in either a shaded area or in a greenhouse to protect them from the scorching sun, all the different type of bug species etc. I am sure you have more of a challenge from your region. Is it possible for you to build a green house?


  1. How To Grow Cucumbers | Garden Harvest Supply - September 21, 2015

    […] Cucumbers also require consistent watering; inconsistent or negligent watering can result in bitter fruit. Water thoroughly two to three times a week, depending upon the climatic conditions in your area. Container plantings should be monitored closely and never allowed to completely dry out. Bear in mind that watering around the roots, as opposed to on the leaves, will provide the most efficient hydration to your vegetable plants and will help to prevent foliar diseases, mildew and leaf scorch. […]

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