Growing tomato plants

Another main stem would be OK providing that the plant has deep roots and that the plants have been sufficiently spaced out. Tomatoes dislike being overcrowded. Remove the leaves that could eventually hide them. Pinch out the small shoots as you are doing and a neighbour of mine used to recommend to pinch out the first flowers as well. It always worked.Honestly, I should be the last person to give advice on tomatoes, when I started my gardening day, more than 30 years ago when we bought our first house with a garden, I pulled out a tomato plant thinking that it was a weed.... My kind neighbour saw what I was doing and started my gardening "education" on the spot. Fortunately, I listened to her advice. She was a remarkable gardener. 

Side shoots will appear where the leaf stalks join the stem cut or pinch them out when they are an inch long.  (You are already doing that).  If you do that regularly you should end up with only one main stem otherwise you would get more than one main stem.  Anything that is coming from below ground (I suspect you covered a leaf with earth and allowed the shoot to grow) should be removed as well when it is short and young.  You may damage the plant if you remove it when the plant is older. If you decide to remove an older shoot make sure you use a sharp knife.Remove yellow leaves below the fruit trusses as the season progresses but do not overdo this deleafing process.  Use a sharp knife (a pruning knife) to remove any unwanted foliage.  You should pinch out the tip of the plant about 2 leaves above the last fruit truss and after it has formed little tomatoes.  This will limit the height of the plant and channel the energy of the plant towards the existing fruit trusses.  How many trusses of fruits you have on each plant before you pinch out the tip is a matter for you to decide by trial and error and  on the variety you are growing.   

Thankyou both for your advice- I'll now go and sort out the plants. Gala I know what you mean about plants & weeds- when I am  growing anything from seed I have to grow it on my balcony in lottle pots cos according to my eyes everything looks like a weed when it first starts growing!

 Helen, I'm really glad to hear that I am not the only one making those mistakes, but it is true, it is very difficult to identify seedlings. And sometimes weeds do look very pretty..... Perhaps we should grow more weeds and less valuable plants. It will be less trouble.

I have come in very late to this discussion, but for next year...if you have missed a shoot that needs to be removed and it is more than about 2" long, you can dip the end in rooting powder or gel, pop it in a pot, and are likely to get a very healthy extra tomato plant from it which will obviously crop later than the mother plant!  

Great idea and it is never too late. Thanks for the tip!