What is the Three Finger Method?
Make a peace sign and extend your thumb at the same time. You should have your thumb, index finger and middle finger extended. Your ring finger and pinky should be closed. The three extend fingers represent a tomato plant. Your thumb is a leaf branch (the branch to keep), your index finger is the sucker branch (the branch to remove) and your middle finger is the tomato stem. I drew a picture to further explain the principle. When in doubt and in the garden, throw out those three fingers and compare it to the tomato section in question.
Keep in mind you typically only prune indeterminate tomatoes and not determinate tomatoes. You prune indeterminate tomatoes as to help keep and maintain the tomato vine that would naturally, if left alone, grow out of control.
|Tomato Pruning - The Rusted Garden Blog|
Identify the Sucker Branches and Remove Them
The branches aren't really sucker branches but giving them a name makes it easier to explain pruning. If they continued to grow they would grow into a vine branch - a branch from the main stem. It would flower and set tomatoes along with the main vine.
A tomato plant is pruned to typically maintain one vine (sometimes two of more) and that will help to develop a strong healthy tomato plant. Sometimes I maintain two vines when I plant a new variety of tomato. That is just my preference. You may chose to let the main stem of your tomato branch into two or three vine branches.
Pruning tomatoes theoretically reduces the number of tomatoes a plant will generate or produce. However, pruning typically means the tomatoes that do grow - grow larger and it significantly helps to prevent diseases and mildews. If you don't prune there is a greater chance for diseases and you might lose the plant and all those extra theoretical tomatoes. You want to maintain good airflow through your plants and let the sun dry them quickly after rains. Pruning suckers helps with this.
If the sucker branches are left to grow it gives an illusion of a healthy green leafy tomato plant. In reality, come another month, a gardener ends up with a plant that is hard to tend and contain in the garden. An unmanaged tomato will have more leaves than needed and the plant will be at greater risk for disease as mentioned. They can grow and become unruly. It sounds counter intuitive but a little less (removing branches) is more when pruning and tending a tomato. I am pointing out two sucker branches in the picture below. You will notice a third sucker branch if you have a sharp eye.
|Tomato Suckers - The Rusted Garden Blog|
These sucker branches are large and that is what makes pruning difficult. It's not that they are hard to remove but that they look so healthy, many gardeners are tempted to let them grow. Don't. Prune them with a knife or snap them off if they are small enough. When my tomatoes are first growing, I am a little slower to prune them. I let some leaves, I would normally remove, hang around a bit in May. After that, they are gone. I do it to provide more photosynthesis to the newly planted tomatoes. It may or may not make a difference but it works for me. You want to slowly prune your tomato as to keep it managed but not remove so many leaves that you slow its growth or put it in a bit of shock.
|Pruned Tomato Sucker - The Rusted Garden Blog|
The sucker branches have been removed. The tomato still looks fine. You will notice my fingers point to the empty spaces where the sucker branches were and you now only see two leaf branches. I also remove bottom branches when the tomato is large enough. This creates a splash barrier and helps prevent the spread of soil borne diseases.
Here is another one of my plants pictured below. It gives you an idea of plant size and the amount of space I keep between the leaves of a tomato plant and the ground. If you enlarge this picture you will also notice two branches coming off the main stem. This is one case where I am growing essential two vines or allowing the main stem to branch into two. I will prune and maintain both of the main growing vines.
|A Pruned Tomato - The Rusted Garden Blog|
Why Prune Tomatoes?
Tomatoes don't have to be pruned but I recommend you do prune them. Tomatoes will still grow if the plant is left to sprawl across the ground without any care. That is what they are designed to do. However, if tomatoes are left to sprawl, they will be more susceptible to disease and mildews. More garden space is needed for a sprawling tomato plant and you probably won't get that many more tomatoes then a well pruned and tended tomato plant.
You prune a tomato plant to greatly reduce the risk of disease and mildews such as blights and powdery mildew. A pruned tomato plant creates a gap between the soil and leaves. It is harder for spores to splash to the leaves and take hold. A pruned plant has less leaves which allows air to circulate through the entire plant.
Better air circulation quickly drys leaves. Dry leaves are a good strategy in reducing the spread of disease and mildews. You prune a tomato plant because you will still get a large harvest of tomatoes without sacrificing space in your garden. A tomato that grows up a stake and has its growth managed, allows more room for more vegetable plants. In my book of a gardening the more space the better. In super summary, you prune to have healthier larger tomatoes and more garden space. It's that simple.
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