Expert: Christopher Littrell - 9/21/2007

Question
i have a white top pitcher, scarlet belle hybrid, and yellow trumpet. their pitchers
are dry with black spots on them. In addition, my dewthread seems to be
browning. They are set by my porch where they get about 5 hours of sunlight
north. can you tell me what's wrong with them?  please help...


Answer
Hello Mary,

It is kind of difficult to diagnose a problem since so many conditions can cause browning and dieback in plants.

The brown and black spots could be normal in your pitcher plants since they catch a number of insects over time and old pitchers brown and die back as the insects rot and become too plentiful. If new pitchers are growing in normally, there should be no cause for concern.

Brown spots and browning leaves in Sarracenias and Drosera could also be from environmental changes occurring too quickly if they were recently purchased and placed in direct sun without a time for adaptation. They might be suffering leaf burn, which is typically not deadly to most high light carnivorous plants like you have. Those species you named are direct sun plants that belong outside, so they should be fine there in 5 or more hours of direct sunlight if they get plenty of ambient light the rest of the day. If leaf burn is the case, watch for new leaves growing in that are ultraviolet light resistant.

Pests can eat carnivorous plants just as they do any other plant. Watch for aphids, mealy bugs, and other sap sucking insects. Many are small and colored to camoflage them as they eat on young leaves in the center of the plant. If you notice any, use a water based insecticide as you would for other plants and only as the manufacturer directs. Pyrethrines, malathion, ortho, and naturally based neem oil can all be used to control pests if you see them... but stay away from soap based products.

Most carnivorous plants can handle quite hot temperatures, but tend to dry and die back in temperatures over 100, particularly if the heat is a dry one. If your region gets that hot for a day or so at a time, make sure your plants are hydrated and kept protected from the hottest part of the day.

Some tips:

Never fertilize carnivorous plants, particularly not their soil. It can kill them if it gets in their soil and can cause leaf burn if too much gets on their leaves. Some people lightly fertilize these plants with extremely diluted fertilizer in foliar feed, but it is just too easy to harm them if you are unsure of application stengths. It is usually best to let self-fertilizing plants eat insects. Potting soil and moss bought in small bags are often fertilized, so be careful if your plants were potted in that stuff. Never use potting soil to pot you carnivorous plants. Use only Sphagnum peat moss in large dry bales and plain dry perlite or silica sand in a 50/50 mix. That mix is fertilizer free, acidic, and drains well while holding moisture in the right amount.

Water them with mineral free water. Distilled, reverse osmosis, or fresh rain water is best. Never use drinking water or tap water as those have minerals and salt added.

Slow adaptation when changing conditions and moving plants around. Constant quick movement can shock them continually and cause them to sicken if they are moved between high and low humidity or temperature areas too much.

Water the plants with the tray method, giving the Sarracenias about half their pot in depth of water in a large tray. The sundews typically like about 1/4 of their pot in a water tray. Always keep the soil moist, but not totally waterlogged. Never let the plants dry out either.

I hope we can figure out the cause of the problem and save your plants.

Christopher