Tomatoes should I cut back, too tall

I started off with Tomato plants, and unlike others, they have all taken and really grown.
Too early to put in an unheated greenhouse.
A few of them are a foot tall, should I let a side shoot start and cut 6" off the main stem ? Or do I just cut main stem and it will grow a new one ?

Never had to worry about early growth before .....

It's just the small cherry plants that have got a spurt on ..... sowing at the start of March was obviously too soon.

 

You can cut the tops off and use them as cuttings.
The plants then will grow new shoots as long as you leave a couple of leaves on.
I've been doing it all winter with a leggy plant that I have over wintered.

 

Do not cut along the main stem for vine-type (indeterminate) tomato plants grown in the conventional way.

This method requires a main leader shoot - the best one is the central shoot at the end of the main stem. The fruit trusses are then allowed to develop along the main stem.

The UK time window for producing tomatoes outdoors is between about mid May/early June to the second week of October so there may not be enough time to develop a good alternate leader from a sucker side shoot.

The best way to deal with a lanky plant is to spiral the stem into a pot in an effort to bury the stem in the compost. Obviously, this can only be done when the stem is young and flexible.

Directly in the ground outdoors, the stem can be buried deep in the soil at an angle with the upper young and flexible portion of the stem trained to the vertical using bamboo poles or string suspended from above.

Cuttings are best done using sucker side shoots without harming the productivity of the parent plant.

 

I've cut out growing points and the cutting then becomes the replacement, imo there's lots of time for the cut down plant to make a new leader.
My outside plants are still at the seedling stage and won't be planted out until early June.

 

I don't want to make a new cutting ...... what I was thinking (and maybe wrong) I could cut off just above where a side shoot is and then that side shoot would take over as the main ?
Didn't expect them to grow so fast .. on a North facing window and yet already 12" high.

 

...... just to be sure ... you saying I can 'take top off' and a new leader will grow OK ?

 

Well I think it will.
Almost all plants do.

 

Just as an update cut about 1/3 off … back to a side shoot … regrew new leader quickly.