Potting up theory - why in stages? How does a large pot stress a plant?
I've been thinking about this with regards my tomatoes, but I'm also curious about it from a more general point of view... I should add that I am a newbie too, with an enquiring mind!
What I'm wondering is, why do plants need to be potted up in stages? Taking tomatoes as an example, why pot them up from trays, on to 7cm/9cm pots, then to 9cm/12cm pots, and then onto their final growing positions? I am presuming that potting them into too large a pot from the start will stress the plant, but how and why?