Q/A #36 - No Dew on Tropical Sundews

February 16, 2023

Q/A #36 - No Dew on Tropical Sundews

I was wondering if you guys can help me figure out what I going on with my sundews. Their tentacles seem to dry up, fall down, then the leaf goes either brown (Drosera spatulata), black (D. nidiformis), or red/brown (D. prolifera). I also have D. capensis. They all share the same soil. I’ve been raising them for around 5-6 months. I’m worried this will spread to my 3 Nepenthes plants (each with their own pot). The sundews have 30-50+ humidity; a 15 hour photoperiod; never below 60° at night and never above 80° in the day. I feed them live insects regularly. I was thinking either root rot or endosymbiotic fungus. I have seen black gnats flying around.
(Submitted in May 2019.)

Drosera spatulata

Drosera prolifera

Drosera capensis

Good news first. Looking at your photos, the lack of dew and browning have nothing to do with fungus or disease; it's environmental. You mentioned a 15-hour photo period, which is good, but your light isn't strong enough. Sundews need sufficient lighting to produce dew. Without it, no matter on the humidity or feeding, they just won't produce dew.

Another clue that your plants are not getting enough sunlight is their color. The tentacles are very pale. They should have a tinche of red. 

Browning will also occur if light levels are too low. Plants get their energy from sunlight, so they will shut down parts of their leaves if they don't have enough energy to maintain the leaf.

You didn't mention what your light source was, if it was artificial lights or natural sunlight from a window. Whatever it is, it needs to be stronger. You can do this by moving the light closer to your plants, perhaps 8-12 inches, depending on the type of light and wattage. If your light source is just a window for sunlight, you may need to consider supplementing with artificial light.

Let me know what your light source is, and send be a photo of what your growing set-up looks like and I can help give some pointers on making it work better.

Another factor that could also be affecting your plants (in addition to low light) is a draft. If your sundews are exposed to a continuous draft, they will always have trouble producing dew. So make sure there isn't a draft blowing on your plants. 

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