DaveW wrote:Yes I believe leaving cacti out in a rainstorm is supposedly more beneficial than watering with rainwater from a water butt since rainwater looses certain elements in storage and they get direct rather than stored rainwater in habitat?
Perhaps small amounts of hydrogen peroxide in rainwater are beneficial. The peroxide would decompose relatively quickly with storage and lose the benefit of delivering extra oxygen to plant's roots.
-Dan
Happy growing!
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Now I have one more question... For a ~half of a year (since last soil change) I was watering with just pipe water. I suppose it has certain amounts of calcyum in it (based on the feeling when I was my hands with soap). How much damage I could cause over this time? The plants seem to be just fine. If I'll switch to slightly acidic water now, will it be OK?
Snowcat wrote:Now I have one more question... For a ~half of a year (since last soil change) I was watering with just pipe water. I suppose it has certain amounts of calcyum in it (based on the feeling when I was my hands with soap). How much damage I could cause over this time? The plants seem to be just fine. If I'll switch to slightly acidic water now, will it be OK?
I call it tap water, but the same thing as what you're calling pipe water. Anyway, you are correct -- tap water has Calcium bicarbonate which makes it alkaline. Since you have a small collection, you can easily acidify your water with 5% vinegar. You'll need to know the pH of your tap water before you can determine how much vinegar to add. And without that determination, you won't have any idea if the dilution of vinegar is too much or not enough. You could test your tap water with pH test strips, although I haven't found them very useful. IMO, a decent pH meter is the best way to go. They're not expensive here in the US, although I don't know about Russia.
I watered all of my cacti with straight tap water throughout the late Spring and Summer of 2011, then I found out about acidifying my water at the beginning of 2012. Any damage caused by the hard water was easily reversed, and the difference in plant health is amazing. However, testing the pH of the water has to be reliable. If it's something you can't do, I would highly recommend watering your cacti with distilled water from your local grocery store.
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DaveW wrote:Yes I believe leaving cacti out in a rainstorm is supposedly more beneficial than watering with rainwater from a water butt since rainwater looses certain elements in storage and they get direct rather than stored rainwater in habitat?
A few thoughts as my plants sit out in their first multi-day rainstorm of the year. My limited experience has also shown direct rainfall to be the best way to water. So, I understand that overwatering causes rot by depriving roots of oxygen, which they need in order to function. Not only is rainwater well-oxygenated, it generally falls for a much longer duration than hand-watering. Do the roots absorb enough oxygen from water to deplete it significantly? Do they do this over a short duration? (It would be interesting to measure this.) If so, the rain would continuously replace oxygen-depleted water during a rainstorm. People here have said that adding hydrogen peroxide to water is beneficial, because it helps deliver extra oxygen; and that watering twice separated by a few hours is beneficial; so it sounds like delivering oxygen to the roots during watering is important.
Unfortunately tap (or pipe water) will vary according to where you live and where the water company extracts it from. The Nottingham UK City Analyst used to be in our cactus club and he told me that there were 8 sources of water in the Nottingham area, so some people could receive water from different sources through their taps at different times of the day. Sometimes from soft water boreholes in the city itself and sometimes from a reservoir in Derbyshire, which is in a limestone hard water area. Luckily where I am is on high ground so they have to pump ours up to our areas own hilltop reservoir, therefore ours is always thoroughly mixed and fairly constant.
A friend of mine was a plumber and used to work for the water board and was employed to take samples of the copper pipe from one area of the city since their water used to eat through the pipes after a couple of years and cause leaks. The point therefore is that with tap water you may be getting very different water to somebody only a mile or so away depending where the water company obtains it from.
Probably the fact that rainwater is falling on the plants for longer than your usual watering CJ will mean the pots get leached far more effectively of any salts build up from fertilisers etc and so get a new lease of life, rather than it being due to the roots being oxygenated?
DaveW wrote:
Probably the fact that rainwater is falling on the plants for longer than your usual watering CJ will mean the pots get leached far more effectively of any salts build up from fertilisers etc and so get a new lease of life, rather than it being due to the roots being oxygenated?
Maybe so, perhaps both contribute. I have little evidence to offer either way. I do normally water with tap water, and observe some mineral deposits. I suppose you could compare plants normally watered with stored rainwater or distilled water, to ones watered with hard tap water, to see whether direct rainfall benefits both or just the tap-watered ones. You could try watering for a long duration with poorly oxygenated water, to see if it gives the same benefit as rain. It would be interesting (but expensive) to get a dissolved oxygen meter (and a way of measuring dissolved minerals).
The recommended ratio for leaching pots seems to be to use at least twice the amount of water the pot itself would hold if it were a water tight container without soil in. So if the pot capacity was quarter of a gallon, flush with at least half a gallon of water. Obviously that is an amount we don't usually use when watering our plants normally, but setting them out in a rainstorm may provide.
DaveW wrote:The recommended ratio for leaching pots seems to be to use at least twice the amount of water the pot itself would hold if it were a water tight container without soil in. So if the pot capacity was quarter of a gallon, flush with at least half a gallon of water. Obviously that is an amount we don't usually use when watering our plants normally, but setting them out in a rainstorm may provide.
Great to know, I'll definitely start doing that. I usually just water until it starts coming out the drainage holes, or submerge the bottom until the top looks wet (which is not more than 5 minutes with my new mineral mix).
I use tap water acidified slightly with plain vinegar, about 1.5 teaspoons (7-8 milliliters) of vinegar per 5 gallons of water gets it down to about pH 5.5 or so. Use acidified water right away for full effect. I only bother with this when it has been a long time between rains (often, here!). Rain is the best.
DaveW wrote:Yes I believe leaving cacti out in a rainstorm is supposedly more beneficial than watering with rainwater from a water butt since rainwater looses certain elements in storage and they get direct rather than stored rainwater in habitat?
I don't know the chemistry behind it, but yes -- rainwater will go from acid to pH-neutral over time. In the desert, thunderstorm activity produces the most significant amounts of natural acidity, but I don't know how long it takes for that rainwater to lose its acidity. Although I think acidification is used primarily to combat the deleterious effects of hard water, I wonder if a small degree of acidification could be helpful in growing cacti with stored rainwater. Worth investigating at least?
I use stored rain water and I acidify it with vinegar. I try to reach the same PH of the rain I get here, but still, nothing beats the good old natural rain.
DaveW wrote:The recommended ratio for leaching pots seems to be to use at least twice the amount of water the pot itself would hold if it were a water tight container without soil in. So if the pot capacity was quarter of a gallon, flush with at least half a gallon of water. Obviously that is an amount we don't usually use when watering our plants normally, but setting them out in a rainstorm may provide.
Leaching involves more than just extra water. The method is to water the pots until the soil is thoroughly soaked, then wait half an hour for the minerals to dissolve before pouring more water in to flush out the first water with the dissolved minerals in it.
It's a good practice to do this at least once a year with all potted plants. It protects against the buildup of excess fertilizer salts as well as minerals from the water. Maybe I'll remember to do it this year...
We have very soft water here, anyway. I do use rain water when I have it, but I don't bother to store it - when it gets mosquito larvae in it I dump it and just use tap water.
greenknight wrote:Leaching involves more than just extra water. The method is to water the pots until the soil is thoroughly soaked, then wait half an hour for the minerals to dissolve before pouring more water in to flush out the first water with the dissolved minerals in it.
It's a good practice to do this at least once a year with all potted plants. It protects against the buildup of excess fertilizer salts as well as minerals from the water.
Even though I acidify my tap water, I do agree that I should flush out my pots once a year. Haven't actually done it yet, but sometime this summer definitely. You are correct about what you just said. However, some gardening forums advise flushing not twice, but 3 times at half-hour intervals. Of course that advice applies to leafy plants growing in rich soils, so I'm not sure if I'd need to go that far growing my cacti in mineral mix.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
