When to stop plants

I have quite a few tomato plants in the greenhouse and some cucumber plants.They are all now getting quite tall so would it be ok to stop them now.If I leave them growing will that affect the size and quantity of my tomatos and cucumbers.

 

Whatever you do there is still 3 months good growing, so seems a waste if you just stop them now.

Mine are also up to the top of the greenhouse as well and what I usually do is carefully bend/train them over and to come back down , like the professional growers do.

You can come back down the same or another a cane or let them grow down the other side of the roof.

The other way would be to stop them at the top, but let side shoot grow out and up for an extra crop....?

What I am trying this year is to stop them at the top, but have rooted a side shoot and will grow that as a new plant, they say it will crop better than the parent plant ...? we will see