Steve Harris writes
On GQT some months back, they gave the results of a trial where they put
1, 2, 3 or 4 tomato plants in growbags. To their surprise, they got the
best crop from crowding 4 plants into a bag.

I'm therefore considering planting my outdoor toms in the soil at much
less than the standard 18" spacing.

Comments?

What did they mean by the best crop? Greatest weight per bag? Or
greatest weight per plant?

For example, if putting 4 plants in one bag decreased the crop of each
plant by 70%, you would still get a 20% increase in the crop from the
bag.

So the decision in this case would depend what was most precious to you
- not much space, plants several plants in each bag. Lots of space, but
only a few tomato plants, then give them each their own bag.

Incidentally, I always used to plant veg closer than recommended - I was
always growing in a small space and found that I seemed to get more crop
per area (and fewer weeds) if plants were touching, even if individual
plants were smaller.
--
Kay