When I first started to grow tomatoes, one of my concerns was to find out what side shoots (also known as suckers), are and where on the plants they grow – and then how to remove them!
Here’s a video that should help explain …
Side shoots are removed from a tall variety, also called indeterminate and cordon, so that the plant’s energy can be used and kept for growth in the main stem and trusses.
Side shoots can be removed when they reach any length but they are easier to spot when they grow to about two inches or so.
As you see in the photo below, it is growing out between the main stem and a leaf branch
Large side shoots can be used as cuttings to start other plants. You can stand them in a glass of water for a week or two, or use root it sponges and rooting gel.
Sometimes tomato growers allow a large side shoot to grow into a second main stem. This has the advantage of growing more trusses at a lower height from one plant
Bush varieties, also known as determinate, do not need their side shoots removed. However, there are situations when it may be wise to remove some of them if growing large tomatoes and you would like the fruit to mature earlier rather than later.
Of course by removing side shoots on bush varieties, you will reduce the number of flowers and fruit that would grow over a long season.