collected rain water always the best?

[sashaeffer]

Any negatives to using collected rain water for watering potted palms (mostly indoor)

I think it's always been assumed that collected rain water is what is best for watering plants/palms indoors but wondered if there is any chance of that there could be issues (environmental contamination) that could affect the palms watered with it.  I know when collected from downspouts it's coming off the roof and with so many roof types out there in the world didn't know if asphalt roofing materials does more harm than good.

Any experiences from members out there?

[Kai]

I have been wondering the same thing. Whenever available I always use rainwater for my indoor potted palms. Appart from a few exceptions my palms all thrive on this. The palms that don't thrive are the ones with poor draining soil or a spider mite problem and are being treated for that. So as far as I can tell with my limited experience there are no downsides to using rainwater.

[Monòver]

I water my potted palms with rain water and they are happy.

My tab water is to alkaline and with high PH. The worst rain water always will be better than my tab water.

[sashaeffer]

I live in the country so am on a well. During the winter when I can't use rain water I will drag out a hose with a whole house filter attached that I use to fill my ponds and then fill up to 10 1 gallon milk jugs that I then keep in the house so when I use that water it's room temp.  Palms seem to do just fine with that water.

 

I notice when I go back to using collected rain water that I get a bit of brown tipping in various species. Don't know if it's coincidence? or the water itself.

[Fusca]

This is an interesting topic because I've wondered the same thing.  I have been collecting rain water for over 10 years for all of my plants and I have lost far fewer container palms since that time.  I've noticed bits of composite shingles collect at the bottom of the bucket (as well as algae after a long dry spell) but no negative affects that I have noticed.

Jon

[XYZ]

Can't imagine problems with rainwater unless you live in the worst, dirty smokestack industrialized parts of the world...today these would mostly be in Asia, not the West.

Volcanic eruptions can also produce nasty acid rain events. I experienced several first-hand in Guatemala in 2010. Not fun at all.

J

[Missi]

On 6/13/2017, 5:55:37, Fusca said:

This is an interesting topic because I've wondered the same thing.  I have been collecting rain water for over 10 years for all of my plants and I have lost far fewer container palms since that time.  I've noticed bits of composite shingles collect at the bottom of the bucket (as well as algae after a long dry spell) but no negative affects that I have noticed.

Jon

Same with my collected rain water (bits from the shingles and algae), but I have only been using it for a year. Good to hear.

[Kai]

Woops! Out of rainwater and unable to get some out of my reservoir, it has become a massive chunk solid matter.

Tomorrow temperatures will be above freezing again but I wonder how long it takes for a piece of ice like this to melt...

[Hammer]

Scott, I would take a sample in to a local aquarium shop. They should be able to run some tests on your water chemistry.   They won't be able to tell you everything you want to know, but it should be enough to give you a sense of things. 

[XYZ]

Barring the exceptions I pointed out earlier and contamination during collection, “yes” rainwater is best for watering palms, as is evidenced by the success of the world’s wild palm populations, even the rheophytes and nypas.

What is worth emphasizing is that if you feed with foliar ferts such as those designed for orchids and other houseplants you may indeed see associated root and leaf burn if you use rain or RO/distilled water to fertigate. By and large, these products are formulated for hobbyists living in urban areas that have crappy, highly mineralized tap water so usually forego buffers. If you mix standard recommended concentrations of these powdered ferts and measure resulting solution with a good pH meter, you might be surprised by a very, very acid reading. While there are ferts out there formulated for commercial growers and BGs using RO water, easiest solution is to always mix mineralized water (tap, ground or bottled) with rainwater at ~1:1 ratio when fertigating.

Hammer’s reco is good. I wouldn’t bother analyzing local rainwater unless you live downwind of a first gen, coal-fired power plant or active hot springs (kidding), but knowing what your tapwater profile is - esp. pH, TDS/conductivity and S, Ca, Mg and B levels - can help you fine tune your fert regimen.