The double stem technique for growing tall tomato varieties is when a side shoot is allowed to grow (on a cordon/indeterminate variety) and become a second main stem. This has the advantage of growing more trusses and at a lower height.
It’s a method of training tomato plants that is frequently used in greenhouses to maximize the production from each plant. You get more tomatoes without the plants growing through the roof – they will if you let them!
Choose Hybrid & Grafted Cherry Plants
Hybrid tomato plants (F1’s) and plants that have been grafted, are usually more vigorous and ideal for this method of growing tomatoes.
Allowing more than one stem to grow on a tall variety is most successful on cherry varieties, where plants find it easier to bring tomatoes to maturity early.
It’s possible to grow more than two main stems …
This photo shows a Sungold (tall variety) that had an accident and lost its main stem – I dropped a sheet of plastic on it!
I’ve allowed three side shoots to grow – one either side (as marked) and one behind. Each new side shoot stem, can then grow more trusses.
For example, if I have one main stem and allow a side shoots to develop, I will end up with two stems.
I can grow trusses from each stem, making a total of as many trusses as I want.
A Longer Season Is Better For This Technique
In a good summer, I’ll end up with more tomatoes, than when growing just one stem with three trusses!
You may ask … how many trusses is it possible to grow?
If you live in an area where the growing season is short, and summers are often disappointing, then the fewer trusses you grow, the more chance there is of success.
In a greenhouse, where the growing season is extended, I sometimes grow more than four trusses on each stem.
It is best to do this in the first part of the season (during June) as side shoots can take a while to grow and produce trusses.
On a vigorous cherry variety like Sweet Aperitif (above), trusses will just do their thing. However, if growing a medium or large fruiting variety, trusses have to be pruned and managed correctly, to produce a good crop.