Expert: Christopher Littrell - 11/7/2011

Question
i grow sarracenia in a terrarium and i have recently noticed a white fuzzy growth in patches on the pitcher leaf esp near the keel and on the hood of my plants--i suspect a mold as i cannot ID any pests.  do you have any idea what this could be and how should i treat my plants e.g. chemical, dose, form of application.

thank you for your help.

Answer
Hello Sam,

This is one of those situations where too many myths circulate about carnivorous plants. There is no reason to grow Sarracenias in a terrarium. The terrarium is the reason why mold (any white, grey or green fuzz or yellow nodules is likely mold)is growing on your plants. Sarracenias do not absolutely have to have high humidity. They can acclimate to almost any humidity down to 15-30 percent so long as they always have plenty of water in a tray under their pots.

First off, use some sulfur based or neem oil based fungicide as directed by the manufacturer of the product. That should help with killing off the mold itself. Second off, slowly harden your Sarracenias to the humidity of your area by gradually opening the top of the terrarium a fraction of an inch every three days. By two weeks or so, the cover should be open over two inches and the humidity should be mostly equalized. Next, after they have adapted to lower humidity, remove the plants from the terrarium and pot them in regular plant pots with over sized trays that can hold a couple inches of water.

Removing the plants from the terrarium will lessen the chance of mold by increasing air flow, increasing light, and toughening the plants' leaves, which makes them resistant to mold. High humidity in closed conditions merely makes the plants' leaves weak and increases the chances that mold can grow on live plants. I grow all mine open pot and have never had a problem with mold other than a short bout with a group of seedlings. The mold never came back and the seedlings survived. The only reason the seedlings had mold issues is due to the fact that they were winterized as seeds for about 8 weeks in the refrigerator before I planted them. Mold grew on them while they sat in the refrigerator, where the conditions are closed, dark, and stagnant. Mold hates ultraviolet light, air flow, and open spaces. Terrariums reduce the amount of light the plants can get due to the extra layer of glass or plastic siding which refracts light and is simply another reason to get the Sarracenias out of the terrarium due to the fact that Sarracenias are full sun plants that would be best outside on a protected, but bright patio. If outside living is not possible for your plants, you will have to obtain at least 25000 lumens equivalent florescent lights to place over them for about 16 hours in the growing season. Of course, they will be requiring dormancy soon, so they will need less light in winter.

Good luck with getting the plants mold free,

Christopher