It's not uncommon to see tomatoes splitting on the vine, which can happen at any stage-green or ripe. If you grow tomatoes, chances are you've watched your beautiful harvest ripen, only to find that the tomatoes you've been eyeing for your BLT have suddenly split overnight (don't worry, they're still edible!).
Why Do Tomatoes Split?
Simply put, tomatoes split either because of too much water1 or rapid fluctuations in water to the plant. When tomatoes go from a dry spell to heavy rain, the sudden abundance of water causes the insides of the tomatoes to grow faster than the outer skin, resulting in the tomatoes cracking.
While both forms of cracking potentially allow pests to enter the fruit or promote rot, concentric cracking is sometimes not severe.
If the cracking is superficial and does not expose the interior of the tomato, you can allow it to remain on the vine to ripen, but keep an eye on it. Green (young) tomatoes that split are more likely to rot before maturity than tomatoes that split at an older growth stage.
How to Prevent Tomatoes From Splitting
Keeping your plants consistently moist helps prevent splitting. By minimizing the impact of a sudden rainstorm, your plants won't suffer the shock of excessive water after ongoing dry conditions.
You can't always prevent tomato splitting; a downpour dumps several inches of rain on your garden in a few hours, which may result in split tomatoes no matter what you do. But you can make it less likely that your tomatoes will split by doing the following:
- Water regularly and deeply: Tomatoes need about an inch of water per week, so water your tomato plants every two to three days during the summer. (Finger test: Stick your index finger an inch into the soil. If it's moist, there's no need to water. If it's dry, give water.)
- Water the base of the plant, not the leaves: When you water, target the base of the plant and avoid splashing soil on the leaves to prevent the spread of soil-borne diseases like blight and septoria leaf spots. Water deeply or use drip irrigation.
- Pick tomatoes early. Tomatoes that have begun to change color will ripen on or off the vine, so harvest them before a storm and place them on a windowsill to complete the ripening process (A side benefit for early harvest: less chance of pests eating your fruit).
- Mulch: Provide your plants with a two- to three-inch layer of organic mulch, such as straw, pine needles, or shredded bark. Mulch helps maintain consistent soil moisture levels, and you'll deal with less splitting.
- Look for resistant varieties: Check the plant's label or seed catalog for types that resist splitting. Many hybrid varieties offer disease resistance and high productivity and are less prone to split.
- Provide good drainage: Planting your tomatoes in raised beds or containers with drainage holes offers the best drainage for your plants if they experience a deluge. Both raised beds and containers drain well-make sure to use good, loose soil that doesn't compact. Because nutrients leech out of containers as the water drains, feed them with an organic fertilizer according to the directions on the label.
- Fertilize correctly: Use a balanced, slow-release fertilizer, and do not overfertilize your tomato plants. Specially formulated tomato fertilizers are high in phosphorus and potassium and low in nitrogen. Excess nitrogen causes fast growth and cracking.
