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Understanding Plant Edema on Succulents

Whether you’re trying to diagnose brown spots on succulents, or you want to prevent them — you’ve come to the right place! A condition called plant edema causes rough spots, bumps or blisters on the leaves of succulents and other plants. These spots can be brown, white, red, yellow or black in color. Succulent edema indicates an imbalance in the plant that you want to correct, but it is not a fatal condition. It’s actually an early warning signal to correct your growing conditions to avoid more serious damage. By the end of this post, you’ll understand plant edema, how to diagnose it, and how to correct it for healthier, happier succulents.

Succulent Edema – a Common Cause of Brown Spots on Succulents

{Please note, some links in this post may be affiliate links to sites that pay me a small commission if you click on the link and make a purchase. This commission is at absolutely no cost to you. I only recommend products and companies that I have worked with and truly love! ~Kat}

What is Transpiration?

Plant transpiration infographic
Plant transpiration infographic

Plant edema is not a disease, but a disorder caused by an imbalance in a plant’s transpiration process. So first, let’s take a good look at transpiration.

Transpiration describes the process of water movement through plants. Roots draw up moisture from the soil, up through the stems and leaves, to every cell of the plant, eventually to be released through the leaves and stem. Transpiration distributes water, oxygen and minerals to all the tissues of a plant. This process is essential to a plant’s survival.

The water released by a plant’s leaves is in droplets too small to see. To get a sense of how much water plants transpire throughout the day, take a large zip-lock baggie and put it over the branch of a plant that is in full sun. Choose a branch with a lot of leaves that can be covered by the baggie. Wrap a piece of twine around the neck of the baggie to seal out the air. Leave the baggie in place for half an hour, then take a look at how much water collected in the baggie. It is the result of the plant’s transpiration. Pretty cool, right? Plants must transpire to live and grow.

What is Plant Edema?

Succulent edema on Graptoveria
Succulent edema on Graptopetalum paraguayense

Plant edema (eh-DEE-muh) is a disorder in the transpiration system that results in small scars on the plant’s leaves. The scars are typically rough, cork-like patches that are often raised like a blister. Typically small and irregularly shaped, they may also appear as white, yellow, reddish or black spots. Edema can affect a wide range of plants, including succulents.

Plant edema (sometimes spelled oedema) results when a plant takes up water through its roots more rapidly than it can process and release through its leaves. Unlike root rot, where roots drown and decay due to excess water in the soil, succulent edema results from healthy roots taking up water more rapidly than the leaves can release it back into the atmosphere. And unlike badly over-watered succulents, where all the interior cell walls burst from way too much water, edema affects a few cell walls near the skin. It is likely that these cells were already weakened or possibly bruised before the conditions that lead to edema were encountered.

Succulents differ from other plants in that they store excess water for the plant’s future needs. They have evolved to take in more water than the plant can process. When you see signs of succulent edema, it is the result of that transpiration and water storage system becoming imbalanced. When this occurs, the excess water builds up pressure that stretches and collapses the cell walls within a leaf’s skin causing irregular bumps or blisters. Edema is the likely cause of small, rough and irregular brown spots on succulents.

Conditions that Lead to Succulent Edema

Crassula ovata Gollum showing several edema scars
Crassula ovata Gollum showing several edema scars

Plant edema results from roots taking in water faster than the leaves can release it back to the environment. But what conditions cause this to happen?

Environmental conditions like air and soil temperature, humidity and air circulation affect the rate, efficiency and balance of transpiration:

  • Typically, plant roots take up water more quickly when the water and/or soil is warm.
  • Too much water in the soil forces healthy roots to take up water more quickly.
  • High humidity or fog slows the ability of leaves to release water into the air.
  • Cold air temperature slows the plant’s release of water into the air.
  • Poor air circulation slows the leaves’ ability to release water into the air.
  • Improper fertilization can also lead to edema.

The most common cause of succulent edema is too much water in the soil coupled with a cool or humid atmosphere.

Diagnosing Succulent Edema

Echeveria with succulent edema
Echeveria with succulent edema, photo credit Rachel Lynch Taylor from Succulents and Sunshine Community

There are a number of possible causes of brown spots on succulents, primarily succulent sunburn, insects or insect damage and plant edema. So how can you tell which is which?

Edema scars can look similar to the damage done by thrips or spider mites. One of the members of my Facebook community for succulent-lovers suggests adding a jeweler’s loupe to your succulent tool kit. It’s a terrific idea! The powerful magnifying glass will show you whether the brown spots on succulents have legs, or whether they’re a defect in the skin, which would indicate succulent edema. (Just in case yours does have legs, or you find pests hiding between the leaves, learn how to treat and prevent succulent pests).

Succulent edema compared to succulent sunburn
Succulent edema compared to succulent sunburn

The loupe isn’t needed to distinguish between sunburn and edema — you’ll see that unaided. Sunburn tends to occur over a broader area, and specifically on the parts of the plant exposed to the most sun. Sunburn is typically flat and relatively smooth where edema scars are often raised like blisters. A sunburned leaf will typically have a single swath of brown, burned skin. While multiple leaves might be burned, you won’t see multiple burns on a single leaf. With edema, it may be a single, small scar or a bunch of separate, little scars that form seemingly at random. Edema blisters can also occur on the underside of the leaf, while sunburn, of course, is always on a surface facing the sun.

Treatment for Succulent Edema

Graptoveria Fred Ives with a few spots of succulent edema
Graptoveria Fred Ives with a few spots of succulent edema

It’s important to remember that plant edema is not a disease. It is not bacterial or viral in nature, and it is not contagious. It is an injury, not a sickness. It is also an important signal about your succulent’s relative health and growing conditions. Edema marks are permanent scars. There is no way to remove them other than removing the leaf, but they don’t prevent your succulent from growing large and lovely. Eventually, your plant will outgrow the scars — if you correct the conditions that led to the edema in the first place.

The solutions for succulent edema look a lot like excellent succulent care:

Follow the practices above to avoid or correct succulent edema. If you do notice brown spots on succulents, and determine they are edema, decrease the water you provide and increase both light and air circulation.

Graptopetalum paraguayense Ghost with succulent edema
Graptopetalum paraguayense Ghost with succulent edema

I know this was a rather dry post, but now you know what to do when you find brown spots on succulents (or white, yellow, red or black). Armed with this knowledge, you’ll be able to correct succulent edema when you find it, or better yet — prevent it! If you have any questions on the subject, please leave me a comment. I will get right back to you!

Happy gardening!

P.S. For more great succulent information, please subscribe to The Succulent Eclectic! I’ll send you my free e-course, 7 Steps to Succulent Success! Thanks!

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P.P.S. Why not join my Facebook Group for succulent-lovers? We talk succulent care, propagation, succulent identification and design. It’s a warm and welcoming group that would love to meet you!

Succulent Edema - highlighted on succulent crassula ovata Gollum
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This Post Has 28 Comments

  1. Annie

    Very Informative. Our Iowa September weather is setting in with cooler nights. I have noticed this happening and will bring my succulents back in under the grow lights within a week. The colors are really coming in through. Better safe then sorry.

    1. Kat McCarthy

      Hi Annie,
      Yes, edema can result in a change of conditions. Fortunately, it is usually just cosmetic and serves as a good warning signal about changes in the succulent’s needs.
      Thanks for the comment!

  2. Lea Gallardo

    Dry? This was one of the most educational posts I read in quite a long time. Thank you. It gives me a whole new way to think about watering.

    1. Kat McCarthy

      Thanks so much, Lea! I’m so glad it was helpful. 🙂

  3. Tammy wheeler

    This post was great! I was thinking I had thrips. I have a few with edema for sure now that I know what it is.
    I’ll have to add a little fan to that room.
    Thank you.

  4. Itala

    Very well explained post! Thank you!

    1. Kat McCarthy

      Hi Itala,
      Awesome! Thanks so much!

  5. Jane

    Thank you!!

    1. Kat McCarthy

      Hi Jane,
      You bet!
      Thanks for reading!

  6. Anne Edwards

    Thanks your site was charged by a FB succulent page.
    Yes my plant has edema

    1. Kat McCarthy

      Hi Anne,
      Glad you found this helpful. And of course, the best news is that with edema, it is not fatal or even dangerous. Increase the light and airflow and decrease the water, and your plants should soon clear up.

  7. Beth Mangus

    I live in NE Fl and I have warm hot cold fog and humidity how do I know how much water to give my husband says we’re not watering often enough so the roots are sucking water too fast!!! I say quit watering so I don’t know what to do

    1. Kat McCarthy

      Hi Beth,
      The many factors like those you list all affect how much water succulents need and how often. A few more would be the size and variety of the succulents as well as air flow. These reasons are why it is not a good idea to try to water your succulents x amount every y days. There are just too many variables!
      Fortunately, your succulents know exactly what they need and when – and they will tell you! 🙂 Read my blog post about how to water succulents to learn how your plants tell you when they need more water and when they are just fine to wait.

  8. Thea

    Excellent info
    very clear ??
    not ‘dry’ at all
    thank you for sharing your knowledge look forward to hearing more and learning a lot more

    1. Kat McCarthy

      Hi Thea,
      Awesome! SO glad you found this valuable! Thank you!

  9. Joan

    I loved all the info! Just what I needed!! Thnx sooo much!

    1. Kat McCarthy

      Hi Joan,
      That’s awesome! Thanks so much for letting me know! 🙂

  10. Beverly

    This was amazing. I googled blisters on echeveria and this was the top result. I *think* that is what is happening to my Echeveria Blue Bird but at least now I have a lead with the term. I have signed up for your list. 🙂

    1. Kat McCarthy

      Hi Beverly,
      SO glad you found this useful!
      If you’d like me to take a look for you, feel free to send me a couple photos at kat [at] thesucculentecclectic [dot] com
      But from your description, I think you’re right, that it’s edema.

      1. Beverly

        Thanks so much! I sent you a note and look forward to your reply. Have a great day in the meantime. 🙂

        1. Kat McCarthy

          Hi Beverly,
          I’ve enjoyed “chatting” with you about your succulent propagation!
          Wishing you many pudgy babies!

  11. Jen

    Thank you for this. Very informative. 🙂 Can you please help me verify if my plants have edema? My Haworthia Retusa and Ice Plant have round, deep, white scars on their leaves.

    1. Kat McCarthy

      Hi Jen,
      I’ll be happy to help! Please send me a couple photos at Kat [at] thesucculenteclectic [dot] com
      Let’s see what we can figure out!

  12. Audrey

    Thank you so much. My issue is caused by them being out in heavy rain which we may have several days in a row. I’ll need to change to a more protected area.
    Thank you for your quick response.

    1. Kat McCarthy

      Hi Audrey,
      You are most welcome!
      Yes, heavy rain can be such a problem. Remember that the adjustments you make to stop edema include improving air circulation and giving the plant more light. So, protecting the succulents from excess rainfall is good. But also watch for good air flow and enough light!
      You can do this!

  13. Lyne

    Great information thanks Kat

    1. Kat McCarthy

      Thanks so much, Lyne!
      I’m glad you found it useful!

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