On 19/10/2014 14:15, stuart noble wrote:
A combination of my own experience and Monty's is prompting me to sow
sweet peas in a couple of weeks time, and over winter under glass (or in
my case in transparent plastic sandwich bags hung on hooks high up on a
south facing wall). Did this 2 years ago and had an excellent show.
However, the polystyrene cups used (I think this helps keep the roots
warm), were way too small (7oz) and the roots were hanging out of the
bottom by February. This time round I'm investing in some 20 oz cups. I
normally cut the bottoms off before planting out but I figure these new
cups with a 6" height might be deep enough for the whole summer root
system.
Does anyone know how deep their roots go in ideal conditions. As I
recall, mine didn't go beyond that.
Any help appreciated

I will be sowing in a couple of weeks as well and I will be sowing into
7cm square pots.
It's not just the depth the roots will go it's also their spread looking
for water when they are planted out.
If you are worried about their roots coming out of the bottom of their
pots then stand those pots inside larger(empty) pots just to stop the
roots going into what ever you have below the pots.
The roots will go down as deep as they can easily grow, depending what's
under them.
David @ a damp side of Swansea Bay