Pruning Tomato Plants for Bigger Yields
Pruning tomato plants gives us consistently larger, healthier tomatoes. So let’s do this! A step by step instructional guide to pruning tomato plants.
Part 1: Back to Basics: Indeterminate vs. Determinate and The Structure of a Tomato Plant.
Before we get into the details and instructions for pruning tomato plants, we need to discuss the difference between determinate and indeterminate tomato plants. We also need to define the different parts of the tomato plant so we can ensure we are cutting the right parts of the plant when we are pruning tomato plants.
Indeterminate vs. Determinate Tomato Plants - This is the way that I remember the difference between the two types of tomato plants.
A determinate tomato plant will grow to a “pre-determined” size. It will grow like a small bush. All the fruits on the determinate tomato plant will ripen and can be harvested at about the same time. A short time after all the fruit has ripened, the plant will die.
An indeterminate tomato plant will grow to an unknown or undefined size. It will keep growing and putting off new growth and fruit for as long as the growing season temperatures and light levels allow.
In this post, we are going to discuss how to prune indeterminate tomato plants.
The Different Parts of a Tomato Plant
The Structure of the Tomato Plant
If we follow the main stem of the tomato plant up from the base of the plant, we have
Main stem
Side Branch
Sucker
Flower Cluster
This pattern repeats itself continually up the plant.
An indeterminate tomato plant is a sprawling, vining plant. The sucker of the tomato plant will have all the parts of the main stem of the plant and will become a main stem itself. It will have side branches, flower clusters and more suckers. And those new suckers will also have side branches, flower clusters and suckers.
Without pruning tomato plants, the plant will quickly overtake our raised bed and/or growing area. By pruning tomato plants, we shape our plant to the size and density we want based on how we will grow the tomato plant during its life.
Part 2: Benefits from Pruning Tomato Plants?
Improve Airflow – Less Disease: Pruning tomato plants allows for increased airflow that will in turn, help to prevent disease. Tomato plant leaves that are in constant contact with one another, or in contact with soil, are at a high risk to develop disease.
Easier to Find Problems and Apply Organic Preventative Measures: By Pruning tomato plants, we restrict the growth of the plant to a manageable size for us and for the root system feeding the plant. This makes it much easier to inspect the plant for insect damage and other problems. In addition to that, by pruning tomato plants, it also makes it much easier for us to effectively apply organic preventative pest management systems like Bt (Bacillus Thurgiensis).
Bigger Fruit: The tomato plant is a vining plant, but it is not a climbing plant. The tomato plant needs our help to keep it vertical. When we keep it vertical, however, we are limiting the nutrient delivery system to a single root system we had when we planted our tomato plant.
Let me explain.
When we look closely at the stem of a tomato plant, we can see small hairs protruding from all over the stem. These hairs, if they were in contact with the ground, would form into additional root systems that would help to feed the plant by delivering the plant additional nutrients from the soil.
Tomato Plant Stem - Future Root Systems
But we don’t grow tomato plants by letting them sprawl all over the ground because it invites disease into the tomato plant. Our tomato plants would just end up a disease-ridden mess in our garden. We grow tomatoes vertically.
And when growing tomatoes vertically, this limits our nutrient delivery system that will feed and grow our fruits to the single root system at the base of our vertical tomato plant.
By pruning tomato plants, we define how many main stems the plant has, and in turn, how many fruits we are ultimately going to grow on our tomato plant. Limiting this number of main stems per plant ensures our single root system is not over stressed. We focus all the nutrients from our root system into fewer fruits, enabling us to grow larger tomatoes. So, by pruning tomato plants, we maximize the size of the tomatoes we grow.
Incidentally, this is the reason we hear the growing “tip” to bury our tomato transplant deep in the ground when planting it in our garden. It’s because additional roots will grow from the stem of the plant that we bury giving our vertical tomato plant a larger root system from which nutrients can be delivered.
It will indeed give you larger fruit. But only if you are also pruning your tomato plants.
My method for growing tomato plants vertically is to grow them against a trellis and attach them with garden Velcro. I love this method because Velcro is reusable year after year and the trellis works great to hold up my tomato plants. The video below is a step-by-step instruction for building this trellis. I use the same trellis for all my vegetables including cucumbers, tomatoes, winter squash and melons.
Part 3: Pruning Tomato Plants – How and How Often?
Step 1: Define How Many Main Branches We Will Grow
When our tomato plant is young, we need to decide how many main stems will we have on the plant? Will we grow only a single main stem and prune off all the other suckers that grow from that main stem for the life of our tomato plant? Or will we allow one or two suckers to grow out when the plant is young leaving us with two or three main stems?
You could choose as many main stems as your growing area will allow. But we shouldn’t grow more than three main stems. Remember, we only have that single root system from which nutrients can be delivered to our plant.
Below is a picture from one of my tomato plants I grew this year. I allowed a single sucker to grow out when the plant was young leaving me with a tomato plant that has grown into maturity with two main stems. Both of those main stems are loaded with tomatoes.
Early Growth Sucker Allowed to Form a Second Main Branch
Prune Off Everything at The Bottom of The Tomato Plant Except the Main Stem(s)
We should prune off all the plant growth from our tomato plant from ground level up to around 16 inches from the base of the plant. This will keep lower-level leaves from being in contact with our garden soil. Tomato leaves, if in contact with our garden soil, are susceptible to various bacteria and diseases that could kill our tomato plant.
Growth Pruned Off of the Bottom of Tomato Plants
Prune Off All the Suckers
We need to regularly check our plant and cut off any other suckers that are growing except those we have decided to grow to maturity. About once a week, we should check our tomato plant by starting at the base of the plant and following the main stem up the plant. At every intersection where a side branch meets a main stem, check to see if there is any sucker growth emerging. If there is, prune it off.
Prune Off Everything Below Harvested Fruit
The last step in the pruning process is to clean up the plant after we have harvested the fruit. The tomatoes will start to ripen from the bottom of our plant. Once those fruits have ripened and we have picked them, we can clean up any foliage that was around those fruits. Prune off all the leaves up to the next set of fruit. That way, the nutrients coming from our root system are not going to be wasted on foliage that isn’t helping fruits further up the plant grow and ripen.
CONCLUSION:
By pruning our tomato plants, we prevent disease and maximize the size of our fruit. Just remember to follow these simple steps:
Define how many main stems you will grow on your plant.
Pick a sturdy method to keep your plant vertical during the life of the plant. My favorite is a net trellis and garden Velcro.
Prune off all the foliage on your plants from the soil level up about 16 inches.
Once a week, check your plants for suckers and prune them off.
Enjoy all those large, ripe tomatoes!
Happy Gardening,
Riley
