Overwatering a Nepenthes : Odema

Overwatering a Nepenthes is an easy mistake growers can make, especially if you’re just starting out in the hobby. Unlike many other carnivorous plants, Nepenthes aren’t considered bog plants. Species like bicalcarata and ampullaria can be found growing in swampy conditions in the wild, but this doesn’t hold true in cultivation. In fact, there are many species that grow as epiphytes high in the trees. Nepenthes appreciate aeration in their soil and if you’re over watering your plants will let you know.

In this article we want to touch on one specific condition you can experience from overwatering a Nepenthes. Odema (oedema) is often times mistaken for a fungus or some incurable virus. It looks a lot worse than it really is and easy to cure.

What is odema (oedema)?

Odema or Oedema occurs when a plant is drinking way more water than it can transpire through its leaves. The cells fill with water and explode. The signs will be invisible at first, but over time these swollen cells will turn brown and look like raised scabs or bumps on the leaves. The shape is usually round, but it can be irregular if multiple cells are water logged. The symptoms usually appear on the older leaves first. There is a very high chance odema will occur when the soil is warmer than the air. The roots tend to take up water faster when they are warm. If the air is cooler, the leaves can’t transpire the water quick enough. Conversely, odema can happen if your water is much colder than the growing environment. In addition, poor draining potting mediums and poor air circulation make things worse. Let’s take a look at some examples belowAs many of you know, leaving the plants can be hard and finding a baby sitter even harder. When we left on our adventure to Exotica Plants our babysitter was watering the plants everyday. Part of our instructions were to make sure the moss didn’t dry out. Well it definitely didn’t, but everything was over watered. The result..ODEMA!

Treatment.

Don’t remove the damaged leaves. Although it’s unsightly your plants will still use these leaves to photosynthesize.

Treating odema is very easy and your plants will recover with every new leaf. The most obvious step is to reduce watering. Nepenthes like moisture at the roots, but they do seem to appreciate when they can approach dryer soil conditions. We don’t mean bone dry, but like sponge that just has had the water squeezed from it. Let’s say lightly moist. Water your plants early in the day. This ensures their isn’t excessive amounts of water sitting in the soil over night.

Use a well draining potting medium. Sphagnum and perlite works well. Depending on your conditions you may have to add other ingredients such as coarse pumice or charcoal to the mix. Remember Nepenthes don’t like to sit in water for extended periods of time.

Air circulation is crucial not only for the health of your plant, but it keeps harmful fungus, molds and other diseases at bay. In our greenhouses, you can feel a gentle breeze at all times. This ensures that any water sitting on the leaves evaporates and the soil uses up any sitting water. Stagnant conditions are a recipe for disaster. Many growers think that high humidity means no air movement and sticky conditions. Both air circulation and humidity can coexist. The trick is finding the balance so that your plants stay humid, but the air continues to move around the plants.

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