was Growing nerines, now clay versus plastic pots

NICHOLAS DE ROTHSCHILD nikko123@btinternet.com
Tue, 04 Oct 2011 09:32:05 PDT
In response to Peter I will add a rider to my comments, we grow all our bulbs on roller benches in a 1 acre ex-commercial Venlo Glasshouse that was designed originally to grow rhododendrons from cuttings. It is tall and airy with good air circulation. We grow all our extensive collection (500-600 varieties) of South African bulbs in plastic pots with the sole exception of Ixia viridiflora because in Graham Duncan's new book on SA Bulbs he says they don't like plastic! and do not have the luxury of being able to plunge our clay pots into cooling sand beds- indeed at Wisley, the RHS garden here in the UK they have the luxury of being able to plunge.
(You can see my new little book of photos of our South African bulb collection by following the links on the nerines web site.)
It could be said that our collection is growing on an almost industrial scale- but it is a private peccadillo- if you have the space one might as well try and fill it....
Its not really lack of insight- it is plain old ignorance and practicality that drives our efforts, oh to have proper plunge beds and the resources and time to mollycoddle each plant... with us you takes your chances and if you flourish, brilliant, if you shrivel and die we'll probably not notice for a season.... we are equally cavalier about our potting mix, (which is free draining), and all our plants irrespective of perceived wisdom about 'this one comes from sand, this one from rock' get the same treatment and all seem to thrive as far as I can see, but then we're not very scientific or botanistic- we just like to have fun with our plants. (Of course see comment above about the self-editing nature of our collection).

We used to have a layer of sand on our benches into which the nerines would put extensive root runs, but the weeds loved the sand too so we only have capilliary matting now, which does have some dampness and the plants do like to put a bit of root into it.
Pip pip.
(and I am HONOURED to be called an expert by one of you....!!!!! Enthusiastic amateur maybe a better description). 
(Happy-go-lucky loony even better)

--- On Tue, 4/10/11, Peter Taggart <petersirises@gmail.com> wrote:

From: Peter Taggart <petersirises@gmail.com>
Subject: Re: [pbs] was Growing nerines, now clay versus plastic pots
To: "Pacific Bulb Society" <pbs@lists.ibiblio.org>
Date: Tuesday, 4 October, 2011, 8:43

I am amazed at the lack of insight into clay pot management. Our pots are
simply tools and as a carpenter may use a spoke shave for one job, he my use
a plane for another.
When I dig up potatoes I use a fork and when I mix compost I use a shovel.

A small clay pot holding a Hippeastrum or Gesneriad, standing on a
windowsill, will dry out very quickly,- so for that I use a plastic pot.
A large clay pot holding Haemanthus albifloss in clay soil, standing on a
windowsill drys slowly and is impossible to saturate, so I use a clay pot to
ensure that it doesn't rot, - plastic would be fine if it were never over
Out side I have a couple of thousand pots of assorted bulbs under glass and
in open plunges. The quickest way to kill a winter growing bulb is to water
it in a black plastic pot and leave the pot exposed to hot sun. The roots
and bulb will cook.

Properly plunged clay will behave as part of the plunge medium with an even
moisture air and nutrient flow throughout the plunge. I find this very
useful for bulbs adapted to hot dry conditions where the roots and / or
bulbs are deep down where they stay cool and moister.
On the scale of individual pots this hot surface and cool base can be
achieved with plastic long toms packed together, as Alberto describes and no
doubt Nick is achieving.

It is apparent that several people have learned how to use plastic and
failed to learn how to use clay. Their failures with clay are because they
don't use clay pots in a way that suits their own conditions and maintenance
regime. It really doesn't matter so long as their plants grow well in the
regime and pots they use. I use both to good effect, and have enough
experience to know that clay pots also have useful qualities.

The "refrigerating effect" Alberto refers to is very desirable for a lot of
bulbs I grow which go dormant when too hot. Before or after a hot day in
late autumn or spring, spraying to cool the plants down will help to
maintain growth and stop premature dormancy.
I think of this as a replacement for early morning dew, or mist, It is not a
drenching and should never be done in hot sun.
Peter (UK)

On Tue, Oct 4, 2011 at 4:29 AM, Alberto Castillo

> It is refreshing to see such an authority as Nick de Rothschild bring some
> reality to this incredibly traditional view.
> The worst effect of clay pots to certain bulbs is the refrigerating effect:
> it cools down when watered and heats as mix dries.
> This is a long list but I grow my bulb collection (and allied plants)
> comprising thousands of them, all in plastic. Not a single one in clay and
> all do perfectly well. Of course the mix in them is very well drained and
> most important drainage holes are carefully cut.

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