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Comment by teruakohatu | Hacker News Reader

I need this! I am struggling to grow carnivorous plants in New Zealand. I think I am giving them what they supposedly need but I just can’t win.

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Just to reiterate what's already been said - don't use tap water. We have a carnivorous plant expert/dealer local to us and he just collects and uses rainwater, as he says tap water will kill them.

Simple waterbutt attached to the drain pipe off the guttering and you get infinite free water for them

Water butt (noun) - British: a large container for collecting or storing a liquid (such as rainwater)

This is so much better than "rain barrel".

Was told the same thing, but my tap water works fine. If it’s true that it’s harmful I’d like to see some science (even citizen science.) Pretty sure it’s a myth.

It's water that builds up limescale that it's harmful for the carnivorous plants. The peat moss substrate that carnivorous plants like is acidic and the limescale neutralizes that.

Plausible, perhaps -- is there any evidence?

Yes there is plenty of evidence that carnivorous plants die in alkaline or neutral soil conditions.

Read literally any book about caring for them. They like acidic soil. Rain water is slightly acidic.

It might take a year or more to kill a plant by slowly draining its soil of acidity. Just like it can take a year to kill a big plant via inadequate lighting.

Probably depends on the location. I've had a bunch of carnivorous plants in Spain, not exactly great tap water, and killed a bunch of them before switching to purchased distilled water.

Depends on your tap water. Hetch Hetchy water has worked perfectly for me for years.

I think it's something in our water, I have to give them purified water which I buy.

Its the water. I have a ro/DI system and use that water. All of the cool low nutrients species have been living for years no problem.

Where abouts in NZ are you? I'm currently based in Wellington and my Venus fly traps, sundew, and pitcher plants seem to be doing quite well on the windowsill.

If it’s the water, could it help to let it stand for a while? I do that to get rid of the chlorine.

Many American cities use chloramine, which requires something like Sodium thiosulfate, but then you're left with Ammonia, which may or may not be desired.

The ammonia will gas off if you let it sit after adding. I used to use Camden tablets (sodium metabisulfate) to treat chloramine water (Philadelphia) for brewing beer.

Beer yeast will make chloramine / chlorine water taste like plastic! Learned the hard way. :)

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