As Susan said there are two types of tomatoes: determinant and
indeterminate. Determinant grow like a bush and then stop.
Indeterminate grow like a vine and don't stop. Just off hand, I can't
think of one heirloom tomato that is a determinant. Maybe somebody will
think of one. In the past, I've just let the tomato rip and enjoyed
watching it climb until it finally toppled over its' support. My
supports are only about 4' high but the tomato would go to over 6'. I
suppose you could build a taller cage. Tomato toppers will tell you to
top when the tomato gets to the top of its' cage. I've never been
disappointed in my tomatoes productivity.

Thing is, when the tomato flops over, a lot of the plant that had been
exposed to sunlight is now shaded by the flopped over top growth. I
could cut that growth off but I would be wasting the energy that went
into growing it. You see where I'm going with this? This year I'm
topping, just to see what difference it makes. Hopefully, my tomatoes
won't be so unkempt and more energy will go into making tomatoes or at
least, in to making them earlier.

You will see that between the growing flowering tip and a side leaf a
sprout (actually a sucker: sucks the energy out of the plant is the
hypothesis). I don't believe these make flowers. Need to check that but
it is vegetation. The reasoning is that with tomatoes, you don't want
vegetation, you want fruit. One way or the other you'll have 'maters but
at some point you may want to fine tune it. A whole lot of people say
pruning and snipping is the way to do it.

I'll let you know how it works out for me.

- Billy
Coloribus gustibus non disputatum (mostly)

A third school of thought ? I remove the suckers until the first set of
blooms appear on the main stem. The theory being that all the initial
energy, after the young plant is established, is going to produce a sturdier
main stem and more or earlier blooms. After that, I remove any that get too
large and in the way.

Suckers DO produce flowers and therefore tomatoes. I've found several cherry
tomato varieties produce an abundance more with suckers left to their own
thing, rather than pinching them. I can't speak for any other size or
variety.

Graveyard Guy