If you transplanted your tomatoes in late April here in North Alabama, by now they should be at least 18″ tall and blooming. Now is the time to start pruning tomatoes. Tomatoes don’t require much pruning, but a little early training and care will improve their health and make them easier to manage.
Assuming you are using a cage system, the goal is a plant with a single strong main stem, and no foliage touching the ground. Foliage which touches the ground is a vector for the fungal diseases early and late blight. These diseases are treatable with a fungicide, but prevention is the best step. The other goal of pruning is to keep the plant foliage open enough to see and pick fruit, watch for disease and pests, and to prevent disease by preventing pockets of moisture that aid disease growth.
If you plants are not yet supported, you need to do so now before the plant starts to vine. Never prune or tie up foliage when wet.
At this age and size:
- Trim off all foliage that touches the ground, by pinch or snipping back to the main stem. Like pruning trees, you want to cut close to the stem, but not in a way that damages the stem — just above the collar. This foliage will eventually become “dead weight” to the plant and die off anyway.
- Remove any tomato suckers below the first fruiting branches. This promotes strong growth for the main stem.
- Don’t remove more than about 25% of the foliage at this point. If you need to wait until the plant gets bigger, do so.
At 24-30″ tall:
- Ensure 12″ of ground clearance at the bottom of the plant by removing all lower stems.
- Continue to remove suckers that form at the axils of the branches. If you are growing a determinate variety, you only need to remove the suckers up to the first fruiting branches.
- For indeterminate varieties, you may choose second and third stems. These should be selected from branches that grow above the first blooms. More stems = more fruit, but a single stem will produce the largest fruit. If you want giant slicers, use a single stem. If you want maximum fruit production by quantity and weight, choose multiple stems. (I use multiple stems.)
- Continue to remove suckers from indeterminate varieties while young and small.
- Watch for signs of disease or pests.