Joe B wrote in message .com...
[...]
2] Why is it necessary to put these small plants into small pots at first if
they are to be moved into bigger pots only a few weeks later? This seems
counter-intuitive to me, since in the wild, and even in the garden, plants
all go into the biggest pot imaginable- the ground- and presumably do not
suffer as a result. I'd really like to understand this.

It's about drainage: in the open ground water moves about, dragging in
oxygen, and has all sorts of other natural factors operating on it.
The way I've always understood it is that in the artifical environment
of a pot the water not being "tapped" by your plant becomes stagnant
and can rot the tips of the roots as they try to move outwards. The
effect is rather like that of overwatering. So you need just enough
volume for your plant to cope with at each stage of its development to
get a steady progression.

I tend to pot on when I first see the tip of a root peering out of one
of the drainage holes, but it's probably better to tip them out and
see if a fair few roots reach to the outside.

Your pelargoniums should recover fine, especially if you don't give
them too much water: they aren't thirsty types. I wouldn't put them
back into a smaller pot unless when you tip them out they show clear
signs of root damage: have the roots managed to grow out from the
original pot shape? If they have, just nurse them along. If they
haven't, I'd go back to the next size down for a while, and they may
be OK.

If I know so much, why do I keep getting it wrong? Ah, well...

Mike.