Wednesday, July 25, 2012

Pruning tomatoes (Part 2 in a series)

If you just discovered this blog, this is Part 2 in a series on growing tomatoes in the home garden. Check out Part 1 here.

Pruning tomatoes is key to healthy plants, which in turn increases production, decreases susceptibility to disease and makes  fruit easier to harvest.
Pruning is particularly important for indeterminate tomatoes. (learn more about indeterminate tomatoes).

Pruning for better production

Pruning helps direct energy from growing lots of leaves into fruit production, and helps with producing more, larger and earlier fruit. Sure, every plant needs leaves for photosynthesis, but not that many leaves. Tomatoes can get particularly leafy when presented with lots of nitrogen as well, so careful with the fertilizer.

Pruning for disease management

There are a number of soil- and air-borne diseases that you can minimize with proper pruning. Early blight is a soil-borne fungus that, when splashed up on leaves, will infect the plant. The good news is blight won't usually kill a plant, but will begin to defoliate the plant from the ground up and will compromise the plant's ability to produce lots of fruit.

As my plants mature and get taller, I start pruning them from the bottom up until I have no leaf branches up to about a foot up from the ground. I also trim back branches that sag down towards the ground, so that there is little to no chance of soil splashing up on the leaves. (A good thick layer of mulch will fortify pruning efforts by minimizing soil splash up as well.)

Pruning will also help with other air-borne diseases that require a moist, still environment to take hold on your tomato. Plants with dense foliage crammed into a tomato cage are just asking to harbor diseases such as fungus that like dark places.

When to prune, and tools

Tomato pruning can begin once a plant is established and has several sets of branches with leaves. As plants get larger, you need to be careful about how much you remove (it's also much more psychicly more difficult to do). And, a heavy pruning after fruit has set risks sun scalding the fruit (which would have toughened up with earlier pruning).

You don't need a fancy pruning tool for tomatoes. In fact, the best tool is already right in your hands. I snap branches and suckers off with my fingers. When I need to remove a particularly large branch, I use a simple scissors. 

What to prune

The big picture here is that you want two main stems to have leaves and fruit. The plant in the image above shows a plant that has been pruned to allow the main stem and one sucker to grow, leaf and bear fruit.

You can read more details about how to prune tomatoes on the Home-grown tomatoes for Wisconsin document. See page 3.

If you'd like to learn more about growing veggies in person, check out the classes offered by Madison FarmWorks and their  Urban Gardener series of classes. It's one thing to read a blog post, it's another to get into the field, see their best practices in action and most importantly, ask questions.

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