QuestionHello, I am a newbie when it comes to carnivorous plants and have run into some questions/issues when it comes to lighting for my Drosera, Sarracenia, and Dionaea. I know all of these require around 14-16 hrs of light per day and I am using halogen bulbs since the weather currently in the midwest has been quite dark. They are watered with distilled water, in peatmoss/perlite mixture soil and are in front of a window. My Drosera leaves had dried out due to recent repotting and since I have used this light some of the dew has come back but very little. The leaves are green which means that they need much more light to turn to their red natural color. This is where my light question came in.
I have bought 2 T5 bulbs, High Intensity. One is 6500K and the other 3000K in order to replicate the spectrum of the sun as best as I can. These bulbs are 24W and 2 feet long each. The light is no more then 5 inches away from the plants themselves and I am using a plastic transparent cover on my plants in order to maintain humidity. Is this wattage enough and will the light get through the plastic? Or should I invest into a stronger bulb with higher wattage?
Thank you in advance for your wisdom,
Yann R
AnswerHi Yann,
You know, I don't have enough experience growing Sarracenia and flytraps under fluorescent lights to provide any feedback. We grow them exclusively outdoors since they are temperate plants native the United States. During the summer, they receive 10+ hours of direct sunlight per day. All I can say is that if you are satisfied with the color, size and shape of the plant, then the lights you have are adequate with those two types of carnivorous plants.
In general, however, you may not see the full potential of these plants under artificial lights as you would if the plants were grown outdoors in full sun. So consider acclimating them to outdoor growing when the risk of frost has passed.
With lights, I use two measurements, lumens and wattage. These two measurements tell me if the lights are strong enough to replicate at least partial sunlight. I don't pay much attention to kelvins because I always use the cool white lights. Their cheaper, and the spectrum output is sufficient to provide excellent growth in my tropical sundews. I haven't seen any significant difference in growth with plant lights or full spectrum lights to justify the much higher cost.
In regards to lumens and wattage, I look for a total of 6,000 lumens or 80 watts. Your two lights have a combined wattage of 48 watts, and I suspect a combined lumen output of 3,000 lumens. What you have is the bare minimum to sustain your plants. They'll look OK under these conditions, but not great. This may explain why your sundew is taking a while to recover from the transplant.
Some species of sundews, such as Drosera binata, don't respond well to transplanting and will take a long time to recover, even under optimal conditions. In either case, if you recently transplanted your sundew, give it more time. It may take up to a month.
It is also possible that the lid, though transparent, is lowering the light intensity. As you've also noticed, while the lid may increase humidity, it has no impact on dew production. So consider removing the lid.
In general, we'm not a fan of terrariums, and we actually guide growers away from using terrariums. There are only a small handful of carnivorous plants that need the controlled conditions of a terrarium. The vast majority found in cultivation grows very well without one as long as they are properly acclimated. I have a couple tropical sundews on my kitchen windowsill, and they grow like crazy. So consider not using a terrarium altogether. You'll find it a lot easier to manage your plants. You will also decrease the risk of losing plants to fungal infection, a problem often associated with terrariums.
For more information about growing Sarracenia, flytraps and tropical sundews (I assume you have a tropical sundew), read our care sheets online:
http://www.cobraplant.com/caresheets
Good growing!
Jacob Farin
