Widely-followed potting-on beliefs.
 

I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which usually
seems to do things quite efficiently, when left alone, out in the wild-and-
woolly wilds...

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

So is the "next-size-up" advice good advice, and if so, why?

Thanks,

Al

Widely-followed potting-on beliefs.
 

On Mar 4, 12:59*pm, "AL_n" wrote:
I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which usually
seems to do things quite efficiently, when left alone, out in the wild-and-
woolly wilds...

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

So is the "next-size-up" advice good advice, and if so, why?

Thanks,

Al

Where in nature do you find plants growing in pots?
Planys grow their roots outwards, so if you use a much larger pot when
the roots reach the outside they will not turn round and grow back
towards the centre.
By moving up slowly you get the maximum amount of root to the pot
size.
If you use liquid feed on your pot plants then they can all make use
of it.
David @ ther wet end of Swansea Bay

Widely-followed potting-on beliefs.
 

In article ,
says...

I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which usually
seems to do things quite efficiently, when left alone, out in the wild-and-
woolly wilds...

On the contrary, nature often provides minimal root space, limited poor
soil, and little nutrition. Plants in that environment have adapted to
thrive in it. Think rocky hillsides, pebbly shores, dense forests.

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

Which is exactly how many plants grow in their native environment, "out
in the wild"; with their roots in very restricted areas competing with
other close vegetation foor food and water.

When plants have evolved to live in cramped starved conditions, giving
them a vast rich soil and root run may produce lush leaf growth at the
expense of flowering and fruiting (figs are an example).

Janet.

If you pot up into a much larger pot, it's a while before the roots reach he outer area of soil. Meanwhile, that soil seems to go stale and musty and yukky. In nature, the equivalent outer area of soil would have the roots of other plants in it.

A more practical reason, if you are planting out a lot of plants, is that you may lose one or two at each stage of growth, and if you lose a small plant from a large pot, you've got a lot larger quantity of compost to decide whether to re-use on another plant.

It's difficult to extrapolate from nature - what you see is the few plants that grew successfully - you don't see the much larger number that didn't.

Widely-followed potting-on beliefs.
 

"AL_n" wrote in message
...

I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which
usually
seems to do things quite efficiently, when left alone, out in the
wild-and-
woolly wilds...

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

So is the "next-size-up" advice good advice, and if so, why?

Thanks,

Al


The main reason is the lack of air and water circulation in pots compared
with the open ground so any compost not being actively used by the root
system has the chance to become stagnant which in turn can start root rots,
its true not every plant will be badly effected but unless I know to the
contrary I try and use a pot that allows my fingers down the side but no
more.


--
Charlie, Gardening in Cornwall
Holders of National Collections of Clematis viticella
and Lapageria rosea cvs
http://www.roselandhouse.co.uk

Widely-followed potting-on beliefs.
 

"Charlie Pridham" wrote in
:


The main reason is the lack of air and water circulation in pots
compared with the open ground so any compost not being actively used
by the root system has the chance to become stagnant which in turn can
start root rots, its true not every plant will be badly effected but
unless I know to the contrary I try and use a pot that allows my
fingers down the side but no more.

Thanks. Would you use the same procedure outdoors with plants inteded to
end up in a large planter/container?

Al

Widely-followed potting-on beliefs.
 

On Sunday, 4 March 2012 18:05:32 UTC, AL_n wrote:
"Charlie Pridham" wrote

The main reason is the lack of air and water circulation in pots
compared with the open ground so any compost not being actively used
by the root system has the chance to become stagnant which in turn can
start root rots, its true not every plant will be badly effected but
unless I know to the contrary I try and use a pot that allows my
fingers down the side but no more.

Thanks. Would you use the same procedure outdoors with plants inteded to
end up in a large planter/container?

Al

Charlie's right and yes I'd use similar rules for outdoor containers (though I usually avoid growing plants in containers anyway) but as the containers get bigger the increments have to increase a little accordingly.

Rod

Widely-followed potting-on beliefs.
 

On 04/03/2012 12:59, AL_n wrote:
I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which usually
seems to do things quite efficiently, when left alone, out in the wild-and-
woolly wilds...

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

So is the "next-size-up" advice good advice, and if so, why?

Thanks,


Maybe I'm playing Devil's Advocate (or just a fool...), but having read
the various replies to your question I think that repotting in a
slightly larger container is one of those old chestnuts which everyone
follows without really knowing why. Actually, it may not be that old.
Looking through some old gardening books (50 - 100 years old) I see no
mention of restricting pot size when repotting. Maybe it's because
there weren't so many sizes of terracotta pot in those days, compared
with the plastic pots we have now. One book does mention putting small
seedlings into 3" pots, then progressively into 5, 7, and 9" pots (was
that "one size up" in those days?). Another mentions putting small
primula seedlings into 5" pots "as that is the best size to show them".
That's quite a jump; it would take some time for the seedling's roots to
wander through the pot.

So what good reasons are there to not overpot? One is to save compost
over the short term. Another, lack of space - I can't see much point in
putting a 10 cm seedling in a 25 cm pot. The greenhouse would soon fill
up! As to the compost going sour, stale, or whatever, I'm not
convinced. Maybe the best thing to do would be to put a few earthworms
in the pot - they'd turn the soil over and aerate it. As to the compost
being too wet in an "overpotted" plant, well, some plants might suffer a
bit and lose some roots to rot. But a small pot, full of roots and with
very little remaining soil, is far more likely to lead to the death of a
plant when it quickly dries out (eg in hot, windy weather). IME I have
lost far more potted plants to drought than drowning. In a bigger pot
with more compost they might have survived.

If you search for "Repotting" on the RHS website you'll turn up over 150
hits. Checking a few reveals the "one size up" recommendation without
giving any reason. Intriguingly, the one referring to "Growing fruit in
containers"
(http://www.rhs.org.uk/Gardening/Grow...uit-containers)
makes no such recommendation. Why? Are these plants such gross feeders
they'll push their roots through a much bigger pot at an express rate?

Maybe it's an experiment I'll carry out one day - potting seedlings into
small, medium, and large pots to see how they get on. Perhaps someone's
already done it. If so, I wonder what they found.

--

Jeff