My nettles build up and rot. The time and consumption of bioflux is extremely high, so I cannot extract enough seeds to keep the Stingfrond farm alive. I would find an alternative recipe for just seeds practical.
The other plants do not require any additional ingredients for seeds.
Otherwise great mod.

Some ideas for your problem:

Try recycling the excess nettles! (I made them recycle into seeds! 50:1, perhaps add some productivity modules to increase seeds over time)
Try turning off your agricultural tower if you have more than X seeds on the outcoming belt to limit its flow, so you only pick the plants when you need the nettles.

Other than that, yes there may be some balance required with the number of seeds returned, I considered making the recycling recipe available in an assembler. That could be another option to make it more accessible.

The problem for me is that I started my game on Gleba. That's why I have balance problems with many mods and would like more settings here and there.
I don't have any recyclers or modules yet. I was just looking for a suitable way to get wood on Gleba and the nettles are more of a casual byproduct. Although I still really like the alternative to nutrients in this mod.

I also have got a new start on Gleba, and thats a big reason why I've been making this series of Gleba mods - if you are not using the Slipstack agriculture one I'd highly recommend.
I 100% agree that a nice wood alternative would help solve many power issues too, although could be overpowered. I've been meaning to make a change to this mod to allow for creation of a poison-damage bullet to help the player deal with stompers a little before rockets. I'll update the seeds return mechanisms at the same time for ya to allow for wood harvesting too.