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Re: Growing perennials in pots???

David Poole wrote:
> 
> Nan Sterman wrote:
> 
> > What kinds of pots do you use and why
> I use plastic (fake terra cotta look-a-likes) and real terra cotta.
> The plastic pots are more practical because they retain water for
> longer - during the summer, this is especially important if I cannot
> get home to water the plants again at lunch time.  The 'real' thing
> looks infinitely better, rapidly developing lichen and mossy
> encrustations which help create an 'aged' look.  Owing to their
> porosity, terra cotta pots are not suitable for drought intolerant
> perennials since even large pots dry out in a few hours at the moment.
> I have a few glazed, imported Korean planters, but I find such things
> a bit too strident for my tastes.  They hold water a bit better than
> the ordinary crock-types though.

Hi
A few general thoughts on containers:-

There are advantages both in plastic and terracotta pots. The two
particular characteristics of plastic containers are lightness and low
permability to water. The lightness is a great advantage with very large
containers, as it makes moving them a practical proposition. A really
huge terracottta pot, once filled with soil, is often impossible to
shift without a crane. However, this can be got round if, when setting
it up, it is  first setteled on a low sturdy trolley with efficient
castors. In small pots, on the other hand, the lightness can be a severe
disadvantage, making them very vulnerable to blowing over in windy
sites. As we suffer here from several months of severe winds every year,
I know all about this problem. The only successful solutions I have
found is a few heavy stones or even small lead weights, at the bottom of
the pot or otherwise standing the plastic pot inside an empty terracotta
one until the windy season has gone by.

Regarding  unglazed terracotta pots and their tendency to dry out, there
are two possible solutions. One is to fit a liner, which could be simply
a plastic pot which just fits neatly inside the terracotta outer. If you
cannot get find a suitable-sized pot, the alternative is a sturdy
plastic bag, such as a rubbish bag. Make several substantial drainage
holes in the bottom when you fit it. Because such a bag is  well
protected from UV radiation, it will last as long as you want it. 
  
The second solution is to obtain a special paint, which is sold for
waterproofing terracotta. I am sure that any large dealer in such pots
sould advise you where to get some. I use one called Terraseal, which is
a cross between clay and putty and which is slathered over the inside of
the pot with a brush. If you cannot find such a dedicated product I have
an idea acrylic paint would work, but I don't know for how long.

Other aids to good watering and moisture retention, which make
dry-weather container gardening easier are water absorbing crystals to
mix with the soil and special detergents which, when applied to the
surface, ensure that the mix is always thoroughly and evenly wetted
every time you water. Here, I can buy such products either singly or in
combination and most commercially-produced pot mixes for outdoor use
already contain them.

If you have to leave your pots all day you could consider fitting a
simple automatic watering system with a time switch. With modern plastic
kits, this is very easy for the amateur to set up linked to a garden tap
and quite inexpensive. It is particularly valuable for hanging baskets,
which are notorious for the amount of watering they demand.

In dry weather, the smaller the pot, the more vulnerable it is to
heating up and drying out. I find it a good idea, in the height of
summer, to move most of my small pots into a partly shaded area,
especially one which is screened from the afternoon sun.

Hope this is some help

Moira
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand/Aotearoa ("Land of the Long White Cloud")
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