Not sure if you should be pruning tomatoes? Well, there is a lot of conflicting information out there, so it’s no wonder people are confused.
I want to talk about WHY there are multiple camps on this topic. There are different strategies depending upon the type of tomato you grow, zone in which you grow, and where your tomato site is. All of these factors could really affect your decision on how (and if) to prune. Let’s wander into the waters so that you can choose which method is going to be best for you.
To Prune or Not to Prune
There is a lot of discussion on whether or not pruning is actually better for your tomatoes. In some cases, there are clear benefits to prevent disease spread and increase airflow. There are also benefits to the vigor of a plant.
However on the other side, there are also drawbacks to pruning, and specifically, over-pruning. You must be careful not to prune too much, because depending on where you prune, you could end up stunting the plant’s growth. More about that in a minute.
Also, the tomato uses the leaves as protection from harsh weather. Harsh sun can scald fruit, and overly wet weather can crack it. The leaves serve to protect the fruit from a number of different weather and temperature conditions.
We should chat for just a minute about Determinate tomatoes before we get too far in. Determinates do not continue to flower or fruit after the first set. They grow to a set (or determinate) size, flower, produce fruit and die off. You only have this one go at getting fruit from a determinate tomato.
The suckers are an important source of fruit production on determinate type tomatoes. Therefore, to get a large harvest, growers are generally careful about pruning suckers of this type of tomato.
This article is primarily concerned with pruning of indeterminate tomatoes. (if you’re not quite sure which type you have, check out this article on the difference)
What is a sucker?
Just like on a tree, a sucker is an extra growth off the main stem of the plant which can grow and act like its own stem. A sucker takes (or sucks) energy and nutrients from the main stem, which is one of the main reasons we take them off trees. It is also why many people like to lop this from tomatoes, too
However, suckers also produce new flowers. They can serve to increase the number of tomatoes you get on a plant.
Pruning Tomatoes
When growing tomatoes and making a decision on pruning, you first must think about the needs of the plant. Your goal should be to help direct the energy of the plant where it is most needed at that point in its lifecycle.
Early on, you want growth to go into the root production. This is why early pinching is absolutely good and recommended in order to stimulate root growth for a healthy plant.
About mid-season you want the energy to go to the fruit production. This is when you want to think about pruning the suckers. This will direct energy to the fruit
Later in the season, pruning is focused on protecting the overall health of the plant by allowing it to protect itself from harsher weather. Lastly you can direct the plants growth into ripening fruit if cold weather threatens.
Pruning suckers = bigger fruit, but fewer overall tomatoes, and fewer late season tomatoes
No Pruning = The plant continues to grow larger (leafier) and keep setting fruit
However that’s not the end of it. You can prune lightly on the bottom of the plant early on to prevent disease from spreading from the soil. Another benefit of pruning close to the soil is that you can more easily see the soil at the roots and monitor your irrigation and moisture levels.
Additionally, you want to keep in mind that your planting zone will affect the pruning decisions you make. If you live in a northern area with short summers, you will probably want to prune more heavily. You’re not interested in the plant setting fruit in October. Late season tomatoes won’t have sufficient time to fully mature and ripen before frost hits. So nipping those suckers improves the overall vigor of the plant.
If you live in an area with longer summers, like here in California, you may not want to prune suckers. Allowing the indeterminate tomatoes to continue to put out new suckers means you will have new flowers and fruit though the fall. I usually continue to harvest tomatoes through December, which is when we generally get our first cold weather. So if you want to keep growing tomatoes in the late season, don’t prune suckers very heavily.
How to prune
Initially, you can focus on lower branches and suckers for pruning. Again, this is primarily to prevent spread of disease from the soil. And also, you want to preserve the overhead leaves as protection. Not including the young plant pinching, I usually start checking to see if the plant needs low branch pruning when it is about 3 feet tall
Pruning is also really helpful toward the end of your season, after the threat of heat waves and sunscald have passed. It is when the air starts cooling off that you need to increase heat to the tomatoes to help them ripen. Pruning late in the season increases the amount of light penetrating the dense foliage.
But be careful – just as the leaves protect from sunscald, same is true with cold. If you are at the end of your season, and there is the threat of a nighttime light frost, your leafy tomatoes will be better able to withstand the cold whereas a ‘bald’ tomato will not.
And I’d like to make one last note about pruning – different tomato varieties do have different characteristics which reward more or less pruning. For example, thinner skinned tomatoes and cherry varieties actually do well with less pruning because the leaves serve to protect them from hotter sun. Certain oxheart varieties tend to be droopy and don’t need their leaves. And tomatoes sited with less than 6 hours of sun a day should absolutely be more heavily pruned.
I hope these tips help you decide your tomato pruning strategy! Let me know in the comments below how you prune!
