On 05/07/2015 12:02, Emery Davis wrote

Was wondering about this as I watched a very welcome rain shower this
morning, but couldn't find much information. Hoping one of our resident
chemists might know something about it.

We all know that root oxygenation is super important for our plants and
in pots can be difficult if soil becomes compacted and/or water logged.
One remedy I've found is using hydrogen peroxide to super-saturate water
for pots, where the plants seem to really appreciate it.

I am not convinced it is super important for most potted plants. It
might be beneficial for some where the roots have particularly high
oxygen demand epiphytes and succulent plants that naturally grow in
rough gravel or scree for instance.

Watching the rain I imagined that rainfall has a high dissolved oxygen
saturation point. But then I wondered, since raindrops form at fairly
high altitudes, maybe this is not so? But anyway rolling across the roof
and down a pipe should oxygenate the rainwater, so that upon filling the
water butt should have healthy saturation levels. After sitting around
for a month though, perhaps not... it does get a bit of a stink to it.

If it smells then it is essentially anoxic which isn't too surprising
with it kept in the dark with a layer of organic sludge at the bottom.

Would this water be essentially anoxic and so problematic to water with?
Or does pouring it into buckets and shaking it around oxygenate
sufficiently?

Not really.

Enquiring minds, and all that... TIA for any insights.

-E

I am not convinced that that many plants need their roots looking after
so carefully. Some orchids and cacti have very high root oxygen
requirements but most things can get by with some flooding.

I have even known some pretty rare cacti and succulents survive a couple
of weeks under water but I wouldn't recommend trying it.
(malfunction of automatic watering system whilst on holiday)

--
Regards,
Martin Brown

In article ,
Martin Brown wrote:
On 05/07/2015 12:02, Emery Davis wrote

Was wondering about this as I watched a very welcome rain shower this
morning, but couldn't find much information. Hoping one of our resident
chemists might know something about it.

We all know that root oxygenation is super important for our plants and
in pots can be difficult if soil becomes compacted and/or water logged.
One remedy I've found is using hydrogen peroxide to super-saturate water
for pots, where the plants seem to really appreciate it.

I am not convinced it is super important for most potted plants. It
might be beneficial for some where the roots have particularly high
oxygen demand epiphytes and succulent plants that naturally grow in
rough gravel or scree for instance.

Actually, it is. Most bought plants are in peat-based composts, which
degrade to impermeable humus. 'John Innes' composts are SO much better
for plants that are actually kept. Few plants can handle totally
anaerobic conditions at the root, though some can.


Regards,
Nick Maclaren.

On Wed, 08 Jul 2015 16:52:37 +0100, Chris Hogg wrote:

Out of interest, how do composts based on coir perform? Are they as
prone to degrading to impermeable humus as peat, or do the coir fibres
help maintain an open structure?

I'm using coir now, with very little peat. Seems to have all the same
problems. Perlite helps, lots of it. Wish I could get composted pine
bark here, I've found a place but it's a 3 hour drive (each way) and of
course they're closed for 6 weeks this summer!



--
Gardening in Lower Normandy

On Tue, 07 Jul 2015 08:12:04 +0100, Martin Brown wrote:

I am not convinced that that many plants need their roots looking after
so carefully. Some orchids and cacti have very high root oxygen
requirements but most things can get by with some flooding.

It is very important for maples, which is mostly what I grow in pots.
It's pretty easy to see when you try to grow one in dense, water-logged
soil. Anyone growing maples knows about this.

Even worse that established grafts is trying to bring up selected
seedlings or understock.

-E



--
Gardening in Lower Normandy