On Fri, 29 May 2009, Chris Hogg wrote
On Fri, 29 May 2009 16:13:07 +0100, Kate Brown
wrote:

Here we are in London and the ground is getting drier, actually the pots
are getting really dry. We have a mains water irrigation system, some
drippers, some sprayers, and use it if there has been no rain for a few
days. But I do notice that the leaves afterwards show how hard the
water is - the lime is left as a whitish bloom where the droplets
evaporated. Is this generally OK or should we try and counterbalance
the lime with an acid drench now and then? We don't irrigate the
camellias which are in a relatively shady area, but a potted azalea
would suffer without the drips when we were away. Otherwise we have all
sorts of stuff - roses, lilies, delphiniums blue and geraniums red -
I'll put up some photos soon on Flickr.

As a rule, though, is a lot of hard water bad or indifferent for most
plants?

I wouldn't use hard water for camellias, azaleas, rhododendrons or
summer flowering heathers (collectively known as ericaceous plants) if
they are in pots. Use rain water if you've got a water butt, and
consider getting one if you haven't. Failing that, dose the pot with
Sequestrine (available as a powder in sachets from garden centres),
say twice a year in the growing season, otherwise the plants will
start to show yellowing of the leaves (chlorosis) and won't thrive.

The ericaceous plants in the soil will cope with a few waterings using
hard water without too much problem, but frequent watering may build
up alkalinity in the soil and result in chlorosis in the plants; it
rather depends on the degree of acidity in the soil and its capacity
to cope with hard water.

Most other plants won't mind a bit of hard water.


Thanks to all, that confirms what I hoped, that if I look after the
azalea separately (and the roses, which do get a bit of blackspot later
in the year) with some Sequestrene (or Miracid? we seem to have a pot
or two of that) then the rest won't mind too much. There's a heather in
a shrubby sort of bed but that doesn't get irrigated and it's been fine
for years, otherwise nothing I can think of. Unless hydrangeas count?
They seem quite happy at the moment, and usually flower a lovely creamy
pink in August. Spider, you're right about the chalky blotches being a
bit unsightly, but without the sprayers on the beds things start to wilt
and also get mildew, which is even more unsightly - at least a shower of
proper rain deals with the chalk!


--
Kate B

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