| Splitting can be caused by uneven watering. On almost-mature tomatoes the skin has stopped growing but the inside tissues are still absorbing water. Too much water (either rainfall or from the hose) at this point in the growth process can result in splitting. Try cutting back on your watering, applying a thorough soaking to the plant only once a week. You can try growing split-resistant type if your weather is such that you can't control the amount of water a plant gets. |
