Expert: Christopher Littrell - 7/14/2008

Question
QUESTION: Hello, I live in Zone 7 Tulsa, Ok.  With high temps typically in the mid 80's to mid 90's lately...give or take.  I've got an anglica, spatulata, and a capensis alba (will aquire adelae and aliciae in the near future).  Right now they're windowsill plants, but the sunlight isn't satisfactory enough to me.  What're your thoughts on these drosera being moved outdoors into more light?  My idea is to keep them outdoors, but will just manually move into shade during excessive heat times.

ANSWER: Hello Keenan,

I agree with you that window light may not be altogether enough for many carnivorous plants. Too many factors intervene like, narrow light entry, intensity reduction from tinting, and intensity reduction from screens not to mention intervening trees and walls.

Most of the sundews you have need high intensity sunlight like they would get in bright partial or bright indirect up to direct sunlight, particularly morning sun. Some markers would be fast growth, red tentacles (for those that have red pigments), and heavy dew production. If the sundews are not producing dew or fail to develop good red coloration, I give them more light as possible.

You could move the sundews outside in a good indirect sun spot to start with, some place with good morning sun streaming down under a tree for partial sun would be great too. Make sure the spot is protected from animals and pests and that the plants will not get dehydrated in too intense heat. Most of the sundews you indicated should be able to tolerate temperatures of about 90-100 degrees, but make sure they are protected from temperatures over that. If that move does not produce the results you want, move the sundews to an even brighter spot a couple weeks later. Just make sure the moves are to slightly brighter spots each time over several weeks to reduce leaf burn and so you can judge how much light they need to develop good color and dew.

The one exception in your sundew collection would be Drosera adelae. That sundew can be kept indoors in a good morning sun window or even a south facing window. This sundew cannot tolerate direct sun and will cook in the ultraviolet light. If you place it outside, make sure it is well protected under a shade cloth or large tree, but that it gets good bright light all day.

You can also use florescent lights to augment window light. I have sets of shelves in front of south facing windows and I have mounted several 40 watt shop light tubes above each shelf. My plants get 6000 to 12000 lumens of florescent light and whatever lumen intensity the south facing window sun gives them. The sundews develop good red coloration and plenty of dew in such lighting, particularly the D. adelaes which have developed purplish leaves and produce huge amounts of dew in such light.

Christopher


---------- FOLLOW-UP ----------

QUESTION: What are the typical temperature ranges for these drosera?  I realize what temps NOT to have them in, but I'd like to know what is actually typically IDEAL for these little guys.  Thank you very much!  
         Keenan

Answer
Hello Keenan,

The optimum temperature would be about 75 to 80 degrees for many sundews, though a few, like Drosera regia and Drosera graminifolia like much cooler temperatures around their roots (generally down to the 60-70 degree range).

The temperates, like Drosera anglica, can tolerate temperatures between freezing and up to about 100 degrees. In pots, temperate plants should be kept just above freezing to keep root death down from freeze drying.

The tropicals and sub-tropicals, like Drosera capensis, Drosera binata, Drosera spatulata, Drosera adelae, and Drosera alicia all should be kept between temperatures of 60-85 degrees. They can often tolerate very cool (down to 40 or 50 degree weather) to very hot (90-100 degree) weather, but do not like it.

Each species will have specific tolerances and exceptions, but in general, all of the plants you are growing really would do best in 75-80 degree temperatures most of the time. In winter, the temperates will enjoy a cooler rest period when photoperiod days are short... I typically give my temperates a 40 degree winter in a sunny winter window and ice chest arrangement. Outside they would just need to be protected from the worst of the freezes with plastic tarps and mulch. Just move the tropicals indoors for year round growth.

Have fun with your sundew collection,

Christopher