Tomato Pruning For Vertical Towers 101

Pruning tomatoes is one of the hardest cultural practices to learn whether growing indeterminate tomatoes up a string or “hanging” tomatoes (determinate or bush varieties) in vertical towers.  Hanging determinate tomatoes requires experience and trials.  It is not as hard as it might appear unless you let things get out of hand. The most common error in growing and pruning determinate plants in vertical towers is over-watering or over-fertilizing and causing “bullish” plants.  I often hear comments such as “my plants are beautiful and so healthy, but I don't have any tomatoes.”  This is not what you want because the over-watering or over-fertilizing is causing your plant to put more energy into creating more plant instead of fruit.  

Training plants to grow down at an early stage is important.  Gently nudge the stems over a little every day until they start to hang.  This is best to do before watering when the plants are not as stiff. Once the plant starts growing down the weight of the tomatoes keep it hanging. Planting larger and more limber plants can also help the plants start leaning.  Depending on your weather conditions it will be about 6-8 weeks before you will need to start pruning.  

The first thing to watch for is that your plants are not touching the ground.  Keep the vines cut up to at least the top of your black ground pot.  This will help you to avoid certain pests and diseases.  Once the plant gets too bushy it is time to prune. First start underneath the plant.  Lift up the vines and remove all dead and older leaves. 

Now it is time to open up the plant.  If you can't see the tomatoes they can't see the sun.  Remove any small or distorted tomatoes.  If a tomato looks more whitish in color than green it was not pollinated and will not ripen correctly.  Then remove any longer vines without flowers or suckers.   Not all suckers have to be removed from determinate varieties, but ones that are just long leaves can be. 

If the plant is overfed you will get a lot of upright growth which will be harder to control.  These upright suckers can be removed.  If you break off suckers, don't worry, more will grow.  Don't be afraid to cut away long shoots even with tomatoes on them.  This is the hardest part for new gardeners but it will allow you to have more, larger tomatoes instead of a bunch of small ones.  You can have 4 plants per tower at 10-20lbs a plant if pruned properly so don't fret about cutting off the small fruit.  If you let your plant get too overgrown you may lose a lot of production to mold, worms and other pests, or just lack of sunlight.  Pests and mold love to breed in dark, humid spaces. 

There is a common misconception that determinate tomatoes only produce once.  This is not true at all.  Commercial growers in the field tend to pick over a short time only because the market window is shorter and the first pick is high quality, firm and have an excellent shelf life.  In Southern climates with a long growing season, determinate tomatoes will produce heavy initially, go through a rest period (especially if temperatures are really high) and then have another heavy production cycle.  Roller coaster weather like we've had this winter in Florida can also cause the plants to cycle. Unless day and night temps are extremely hot (above 90°F/80°F respectively) or cold (below 52°F) then you should have a fairly steady supply of tomatoes.  Too warm or too cold will cause the plants to stop producing flowers.  Varieties can also affect how much production you have.  Roma tomatoes and grape tomatoes can have abundant production whereas your larger tomatoes may cycle more.  Grape and cherry tomatoes do not have an indeterminate variety and will produce long vines.  These need to be pruned as well.  

The best way to get started if you've never pruned before is to cut the long stems up off the ground, clean up the dead leaves from underneath, and thin out some of the excess growth and small tomatoes.  The plant will still need some leaves for photosynthesis so don't go too crazy.  If a tomato is showing any signs of color it will not get any bigger.  It will take some trial and error but you will get the hang of it!

Best of luck and any questions please ask!  We'll be posting a YouTube video soon to give you a better visual.  

Scroll down for a short video on removing suckers

-Tim