Why Do My Tomato Seedlings Grow to 2 Leaves Then Stop?

Germination and Sprouting

• Tomato seeds require light, warmth and moisture in order to germinate. Once the seeds have reached 30 percent moisture levels, the seeds will begin to germinate, sending down an embryonic root to provide the seed with more nutrients and water. After time, the seed will send up a sprout, which will become the visible portion of the tomato seedling.

Cotyledon

• The first visible portion of the tomato seedling is the growing point, which is the tip of the embryonic shoot. The first set of "leaves" that are visible are two rounded flat "leaves." These are not true leaves, but are the cotyledon, a part of the embryonic shoot. The cotyledon provides nutrients for early plant development through photosynthesis.

True Leaves

• True leaves on tomato seedlings appear two to three weeks after initial emergence. The first set of true leaves will appear is a different shape than the cotyledon. The leaves will be longer and variegated, with multiple "teeth" per leaf. The leaves will appear in pairs, and will be held by slender branches to the main stem of the tomato seedling.

Root Development

• During the time between the emergence of the cotyledon and first set of true leaves, the tomato plant may appear to be dormant. This is because the tomato plant is in the process of developing a more complex and mature root system. A stronger root system will ultimately ensure a healthier adult plant.

  As the initial embryonic root becomes the taproot of the tomato seedling, it will send out smaller feeder roots, which will provide extra stability to the tomato seedling, as well as providing more nutrients and water to feed the plant. This stage is very important to the development of the first set of true leaves, as the seedling requires a lot of energy to produce its first set of true leaves.