FlytrapCare Carnivorous Plant Forums

Good question, I've never fed mine, on the principle that it grows in a nutrient-free (ish) environment when growing in/on peat which is what I normally grow it on, but when grown in trays of water with a couple of handfuls of ordinary garden soil it does seem to be greener but not necessarily bigger or faster-growing.
I would like to know this too.
Cheers
Steve

I would only feed it if it looks pale and sickly. The problem I've seen with feeding sphagnum is that it promotes algal bloom and slime molds.

Instead, I'd focus on dialing in the cultural conditions first. It should grow just fine without fertilizer and feeding it is optional, honestly.

I also have some red sphagnum and was impressed with how much light it needs to show color. It's basically growing within 3-4" of some generic led shop lights and seems to like those conditions, as long as I can keep it from drying out.

If/when you decide to try fertilizing it, I would start with a very dilute solution and slowly dial it up. You want to find the sweet spot where the sphagnum is getting a boost but the algae and slime molds are not.

Hope that helps and good luck!