Posted: 04/07/2015 at 07:40
I can't stress enough how inherently tough tomato plants are, forget-me-not. I think I've told the story here before about the plants I swapped with my local fruttivendolo (greengrocer). He would dig his up out of the ground - they'd probably been in the ground a couple of weeks - and jam them into a bucket with only the soil attached to their roots.
One year he gave me too many. I left two in the bucket - still with only the soil attached to their roots - and forgot all about them. They sat in full sun in temps into the 30s without water, fertiliser, anything. I came across them later in the season. They'd more than doubled in size and one had started fruiting before it died.
It's a worthwhile experiment to isolate one potted plant and give it a minimum of water and fertiliser. Just keep it alive. But make sure that the watering regime, whatever it is, is regular. Irregular watering patterns will stress a plant and could cause problems like Blossom End Rot. Compare the plant's performance against the others at the end of the season.