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What is Plant Edema and How to Treat it?

Taking care of your own garden often means having to deal with pests, weather changes, and plant illnesses. It’s never fun to have to face them, but the good news is that some are easier to treat than others, as long as you know what to look for. The most common ailments include various diseases, infections, and conditions, such as plant edema.

Plant edema is a cell-damaging condition that occurs in some plants due to high water retention. It’s caused by environmental conditions and can be treated relatively quickly by managing those conditions through control of watering, ventilation, and crowding.

Even if it isn’t an urgent condition, plant edema is still a problem to be taken seriously by any gardener whose crop it is affecting. If you’re able to identify it early, you should be able to solve it without suffering any significant losses.

Photo of a plant with exposed roots soaking in a fishbowl half full of water
Photo by Kids Nord

What is Plant Edema?

Edema, sometimes spelled oedema, is a disease in certain plants that causes an increase in pressure in the leaves’ cells, which leads them to rupture and leave visible blisters on the undersides of leaves. There is more recent evidence that suggests the cells don’t fully rupture, but rather stretch and collapse, although this doesn’t change the overall outcome of the condition very much.

Plant edema affects a wide variety of plants, but is most common in:

  • Geraniums and similar flowering plants
  • Sweet potato vines
  • Cacti
  • Greenhouse tomatoes
  • Cole crops like broccoli

It’s also common in peppers and similar plants. According to Growing Produce, there’s a good chance that any plant with succulent, or thick and water retaining, tissues is susceptible to edema if introduced to the right conditions.

The Difference Between Human and Plant Edema

In people, edema refers to an abnormal retention of fluid in connective tissues. It can be referred to as dropsy or hydrops, and is frequently a symptom of a larger disease rather than an independent condition.

These two shouldn’t be confused; where it is a serious condition in people, it is not in plants, and is definitely not caused by the same things. Human edema is caused by internal conditions like issues with the lymphatic system or by allergic reactions; plant edema is caused by environmental conditions.

It’s also important to note that you can’t catch edema from a plant affected by the condition. There is nothing infectious about the blisters and dry spots in plants because they are dead cells and not growths or pustules. Plants with edema are safe to handle and consume as we will discuss later in this post.

What Causes Plant Edema?

Edema is a plant’s response to environmental factors, most notably, an excess of water retention. Keeping a plant in conditions that cause it to take in water faster than it can be lost will cause it to start bloating, just like a person does when they are retaining too much water. This bloating can become edema if it’s not caught early enough.

Some common causes of edema are:

  • Overwatering
  • Improper soil mixes for the type of plant
  • Improper fertilization
  • High greenhouse humidity
  • Being potted in too small a container
  • Crowding planters

It can also be an issue of unequal distribution of water and nutrients in an open field. If you notice edema in only one section of plants, it may be a sign that you need to evaluate what’s going on in that particular place.

What Does Edema Look Like in Plants?

The most noticeable signs of edema are blisters. These growths on the bottom of the leaves may be white, tan, or brown, and may look like warts or pieces of cork. The leaves themselves might turn yellow and become fragile or droopy, and may eventually wither and fall off. In rare, very severe cases, the stems might even be affected with the same growths.

These plants will usually be otherwise healthy and firm, given that edema is a very localized condition until it is extremely advanced. If you notice excess softness, darkness, or other unusual appearances or inconsistencies in your plants, it might be a sign of a different problem.

Consider isolating plants that appear more infirm or ill than others so that you can identify any additional problems without worrying about them spreading.

Is Plant Edema Contagious?

The short answer to this is no. Edema isn’t technically a disease so much as it is a condition caused by controllable exterior factors in your growing environment, which means that it’s impossible for it to be spread from one plant to the next, as there is no biological carrier for the condition, and each individual plant will have different reactions to different environments.

That being said, plant edema may seem to spread from plant to plant if they are all kept in the same conditions, as it might happen in multiple individual plants at once. This may make it easier to tell what the exact contributing factors are for the condition, as it will only affect those plants to whom the condition applies, such as those in a bed or container that is overwatered or overcrowded.

Is Edema on Edible Plants Still Safe to Consume?

Because edema is a condition and not a disease, fruits and vegetables from plants affected by it are safe to eat. That being said, the main problem with having vegetables affected by edema is that they become unsightly, meaning that they don’t look as good and are unlikely to sell well.

If they are for your consumption, simply cut away the affected parts of the vegetable before eating. Be absolutely certain that it is edema, though, as some infectious diseases and insect infestations can look similar on the surface. You should also be wary of any rot that may have taken hold because of extended exposure to moist conditions. If there is any doubt, it’s better to be safe than sorry, and avoid eating any produce that may be compromised.

How to Treat Plants with Edema?

You’ll want to reduce the amount of water you’re giving the plant without letting it dry up completely. You may also consider moving the plant to a larger pot, so that there’s more soil to absorb and regulate the water it’s receiving. Make sure the soil you use is pH balanced and has appropriate amounts of nutrients like potassium and calcium by performing regular soil tests.

If you’re raising plants in a greenhouse, you’ll want to adjust the following factors:

  • Make sure the humidity isn’t too high so that water loss and water uptake are balanced.
  • Keep the room well ventilated to encourage evaporation.
  • Keep the room relatively warm for the same reason.
  • Make sure that your plants are organized in such a way that excess water has proper drainage.

You can try increasing the amount of light your plants are getting as well, as this will help encourage water loss and balance. Just make sure you’re not cooking your plants in direct sunlight and/or too much heat. Change your plant’s sun exposure gradually, over the course of one to two weeks, to allow it time to adapt to the changes.

Plants Can Recover from Edema

Thankfully, most plants affected with edema, if caught early enough, will make a full recovery and start producing completely healthy leaves, stalks, and fruits within a few weeks or months. Environmental factors are relatively easy to correct, and with enough care and attention, your plant will be good as new in no time.

Here are Some of my Favorite Gardening Products and Tools

Thank you for reading this article. I hope you found it helpful for growing some new plants in your home or garden. Here are some products I like that I hope you’ll also find helpful. These are affiliate links, and I am compensated for referring traffic. But in all honesty, these are the exact product that I use or recommend to everyone.

Soil: For high-quality soil, I really like Fox Farm Ocean Forest. I do all my growing in containers and this soil has worked great for me. I like how they use nutrient-rich contents like earthworm castings, bat guano, and composted crab and fish.

Fertilizer: Currently I am using a seaweed-based organic fertilizer call Neptunes Harvest. This is a great milder fertilizer option if you want to use something organic. If you want a more powerful fertilizer, I recommend Fox Farm Liquid Nutrient Trio, lots of people have had great growing success with this product.

Pruning Shears: Pruning shears are one of the most useful gardening tools to have because it’s important to prune your plants to keep them healthy. The pruning shears I recommend are the Gonicc 8’’ pruning shears. I like them because they are built sturdy and work both on bigger and smaller plants, so you don’t need to have multiple pruning shears. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to also participates in affiliate programs with other sites. is compensated for referring traffic and business to these companies.