If you are new to vegetable gardening, you probably have heard the phrase “true leaves” a time or two. This is especially true if growing from seed, where this phrase is used most often. But what exactly are true leaves?
When a seed first emerges from the soil, or potting mixture, it has a set of two leaves called cotyledons. The cotyledons are actually a part of the seed, and act as a food source for the sprouting seedling. At this time the seedling does not conduct photosynthesis. It gets all its food and nutrition from the cotyledons.
As the seedling becomes stronger and healthier, it will begin to form two more leaves that look very different from the cotyledons. The true leaves will look more like what the plant’s leaves look like when mature. Once the true leaves are present, the plant is now actively photosynthesizing. Eventually the cotyledons will wither and fall off as the true leaves take over the job of feeding the plant.
Knowing how to identify a seedling’s true leaves is important if starting seeds in pots for later transplanting into the vegetable garden. Some vegetables should not be transplanted in the vegetable garden until at least two true leaves appear. This is true for cucumbers, squash, pumpkins, and melons. Hopefully now you understand what is meant by “true leaves”.