Pruning Tomatoes

 

Most internet info suggests that pruning off suckers on tomatoes is a good practice, but if often doesn't explain when and why to prune.  Pruning tomatoes is not always a good idea or needed.  Wheteher to prune or not depends on the type of tomato and your goals. 

 Indeterminate tomatoes are the only tomatoes you would consider pruning. Indeterminate tomatoes continue to grow vines and fruit until the first frost.  Understanding the structure of a tomato plant will help you understand what and when to prune.

In this photo you can see the main stem with a flower cluster coming off and and
leaf node on the opposite side.

Structure of Tomato Plant

Main stem, leaf node, flower clusters, and suckers are the parts of a tomato plant.  The leaf nodes and flower clusters grow off the main stem.  The suckers grow in-between a leaf node and the main stem.  Most suckers on indeterminate tomatoes become additional main stems that will produce flower clusters. If this is the case why would you want to prune?

Reasons to Prune Indeterminate Tomatoes

• Accomadate a vertical support system which is typically used in a greenhouse. If you live in an area with lots of wind I don't recommend growing vertically outside unless you have wind breaks. The high winds in my area are hard on any vertically grown plants Also if you have no afternoon shade for your tomatoes I don't recommend vertical growing.  More leaf growth will shade plants and prevent sun scald on fruits.  I'm in Utah and sun scald is an issue here. 

These are greenhouse tomatoes that have overgrown their cages.  
Next year I will be growing vertically in the greenhouse.

• Prevent the tomato from overgrowing your cages or support structures. Overgrown vines can break if not supported so either get better structures or prune out a few suckers to prevent too many main stems from overtaking your structure.

• Manage airflow to prevent disease.  

• Increase the size of beefsteak or novelty tomatoes by pruning and removing some flowers.  The more flowers and fruit the smaller the fruit.  This is more a novelty issue if you want large beef steak tomatoes.

• Pruning out diseased leaves but remember that pruning in humid climates will leave a wound for entry of more disease.  In dry climates you can prune off diseased leaves.

• Prune lower leaves below the first flower cluster.  This is helpful in preventing soil born diseases.

Why grow vertical?

 Limited space and wanting to grow more varieties is one reason to grow tomatoes vertically.  Growing vertical allows you to plant closer together and plant more varieties.  If you are not worried about spacing allow to the indeterminate tomatoes bush out.  

Growing vertically works well in a greenhouse because it allows light to penetrate the plant and provides good airflow.  This will allow tomatoes to ripen faster and prevent disease.

Tomatoes NOT to Prune

• Cherry tomatoes need no pruning.  Let them vine out.
• Determinate tomatoes grow to a certain size, stop growing and produce fruit. Do not prune determinate varieties.
• Semi determinate tomatoes should not be pruned.

For review, removing suckers limits the number of main stems and the number of fruits that will develop. Be sure you have a reason and purpose to pruning.

When it comes to pruning shears STIHL is the only brand I recommend.  When pruning be sure to wipe the blades with Clorox wipes when moving to a new plant.  This will prevent spreading disease.

Pruning shears