Posted on June 18, 2009

The Pruning (or not) of Tomatoes

I think there are a million opinions on how to prune indeterminate tomatoes. At least, there seemed to be a million when I went to do some research on the subject. While I’m not going to tell you I have all the right answers on pruning tomatoes, I will tell you what I did and how it worked for me.

My first experience in pruning tomatoes was actually an accident. I never pruned my tomatoes before the year my toddler daughter decided to cut off the tops from our snow white tomato seedlings. While I thought it would just kill the plant, it didn’t … the end result was actually some really nice, compact plants with a lot of delicious tomatoes. The following year was a bad year in terms of weather, and I trimmed the tomatoes back to allow more airflow into the bush as it seemed to be making mostly leaves and no tomatoes. It helped, but the main problem was the weather and not the pruning itself.

If I had endless amounts of space in my garden, I would just let all my tomatoes go without pruning them except in cases of damage or disease. As that is not the case, this year’s pruning is done in terms of heath and space. Please note: I do my pruning in several passes in order to evaluate the garden as a whole, because it’s not just each individual plant that matters but the health of the garden as a whole.

Step 1: Evaluate and Support as Needed

Sit down and look at all of your plants for a while before you begin pruning. (I really think that careful observation is a very important and underutilized skill in gardening.) Do you see anything drooping? Curling? Yellowing or a different color than the others? Does anything need to be staked or straightened to allow to healthier growth? Is something not getting enough sun and should be moved? Take care of all of these things before you begin pruning.

Step 2: Prune for Health

On my first pass at pruning, I take off any branches that look like they are struggling, yellowing, diseased, or too low to the ground. You never want a full branch of tomatoes on a weak branch or one too low to the ground, because the branch will just bend or break before all those tomatoes can get ripe. Leaves and tomatoes that lay in the ground are also more prone to damage, insects and disease, like this:

I also like to take off lower leaves and stems if I feel like a plant is too "bushy" because it seems like those leaves keep me from being able to easily water the base of the plant. A before (top) and after on this kind of trimming on a Stupice tomato:

Step 3: Prune for Overall Garden Benefit

If you have a large garden with ample room, you may just want to stop now and leave your plants as they are. If not, you may want to prune for the health of the "herd". In my garden, I grow rows of basil and flowers below the rows of tomatoes, so I trim off enough bottom branches from the tomatoes to give this kind of clearance:

You may have other criteria for this third step, such as wanting to trim off the suckers (side shoots) from the tomato plant to keep the plant compact, or clipping off the top to keep the height down and encourage more growth of the suckers. I tend to keep more leaves on the upper parts of the plant, to shade the soil so it will retain water, but some people like to clip more leaves off if they have more problems with insect pests. Just remember: Your pruning will vary year to year, try to learn from your experiences, and it’s better to not prune enough than to prune too much.