Question
Hi, Mike.

I live approx. 80 mi. N.W. of Chicago, in N. Illinois.
My dad loved growing tomatoes, starting the plants from seed in his basement, and transplanting them outside at the right time.  He lived in the same area as I do.  He mentioned pruning the plants to get more tomatoes and less plant, which makes sense, because we don't eat the plant!  I have a few tomato plants and want to get the greatest yield from them, but I don't think I ever knew how he pruned them (or don't remember).  Unfortunately, my father is no longer around to ask, so maybe you can tell me the procedure.  By the way, we have them caged, and my wife uses Miracle Gro on them.
Thanx for any info.   Jack

Answer
Jack, I never recommend topping off a tomato plant.  Only the suckers should be pruned; never the primary stem.  You can prune side stems if the plants begin outgrowing their alloted space and shading other nearby plants.

The suckers are the growth that occurs between the main stem and the leaf axil of the flower stem.  Eventually, if allowed to grow, they branch out into their own plant.  By leaving these on, the plant expends much of its energy into the new growth rather than producing tomatoes.  You end up with more tomatoes over the long run, but sacrifice size and space.

The reason I prune the suckers is that I prefer the larger tomatoes and more compact growth.  Not only do you have a neater appearance to the plant, but you also have much better air circulation which means the plant is less prone to fungus diseases.  To prune, simply snap or cut them off when they are about 2" in length.

One piece of advice that may help is to not apply too much fertilizer.  Many gardeners use commercial fertilizers that are very high in nitrogen.  These tend to result in lush foliage at the expense of fruit.  Instead, use a fertilizer (such as fish emulsion) that is very low in nitrogen but high in phosphorus and potassium.  You can also use a water-soluble fertilizer specifically manufactured for tomatoes at 3/4 the recommended strength once every two weeks.

Attached is a website that illustrates various methods of pruning.

http://www.taunton.com/finegardening/pages/g00031.asp

I hope this helps.  Good luck, and please write again if I can ever be of assistance.

Regards,

Mike