Any advice on using rainwater?

I’m getting gutters installed soon and I’ll be using a rain barrel to catch a lot of it. I’m wondering if there’s anything that I’ll need to add to it in order to make it appropriate for my trees. Clearly they get rained on naturally, but are there any issues with rainwater being the only type of water that they get?


I have been using this for a few years to collect rainwater. I do nothing with the water. I just water.


If you are pulling from the downspouts, I’ve heard some people say you should discard the water from the first storm of the year (pulls up extra tar or whatnot from your roof).

Other than that, you might need to check the ph and adjust for that but that’s highly unlikely as rainwater is pretty good ph wise.


Ah, good point about the runoff from the roof.

Depending on your local conditions, a rain barrel could empty in less than a week of watering. It may be worth looking into rain water bladders with larger capacities. Get the largest you can reasonably afford :slight_smile:

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My yard is tiny :confused: :sob:

You can sneak them under the deck… if you have one, that is :slight_smile:

Lol, I wish. My house is up on stilts which is where the garage is located.

Man, that’s gonna limit the options… biggest tank you can reasonably afford, then.

Lol, perhaps some day.

The average rain water is around 5.7 ph. (I think it’s pretty standard round the world but it may be worth checking locally). So it’s good for most trees including azaleas. I empty and wash mine out during January to get rid of algae and sludge which accumulates. This year though, we’ve had so much rain I’ve simply half drained it about four times instead.

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I store about 1800 gal. of rainwater in 7 of those cube tanks. I just use it as it comes out of the tanks. Rainwater has so little nutrient in it that it does not promote much algal growth and I don’t have to filter it. I use it on all my tender trees and anything in a show pot because my regular tap water causes mineral buildup on the pot. Trees in training pots may get conditioned tap water when the rainy season ends. If you can get it rainwater is the best for any bonsai.


Just a follow up to this; this past weekend I finished upgrading my single barrel setup to a three barrel setup. Next I need to install a screen to block the view from both myself and my neighbors. One barrel was tolerable. Three is quite ugly imo.


Put in a hedge!
Invasion of the pod people…
Looks like you are brewing,or making kimchee for the whole neighborhood…:kissing_closed_eyes: :wink: :rofl:!
I suppose I would have to taste your local water before criticizing. Mine is almost perfect… doesn’t rain her much in the summer anyway, desert… High mountain fed aquifer.
Bonsai On!

Nice! Our water has a pH of 8.4. Much too high for my tiny trees. I do use it on occasion for the calcium…which I assume is in there. I also use CalMag, so :man_shrugging:t4:

Nice. Where did you get the black barrels from? Been looking for some other than the bright blue they typically sell.

Found them on Facebook Marketplace. They’re used to ship pickles, so they’re food grade barrels for whatever that’s worth. They even still smelled like pickles lol.


I try and use rainwater whenever I can. That being said we’re in the middle of a heatwave and as I have way too many trees (at all stages of development) in pots I do unfortunately resort to the hosepipe even though the domestic water has a pH of 8.5 on a good day, higher on a bad one.
The one thing I find hard is keeping the water butts cool. Even though they’re shaded the water by the evening is just slightly cooler than tepid.

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