When the seed of a flowering plant germinates it has one goal: to gather light for photosynthesis as quickly as possible. The carbohydrates generated by this miraculous process are absolutely necessary for further growth.
The first leaves to appear above the soil’s surface are known as “seed leaves”. They are packed within the seed in compressed and rudimentary form and typically have little or no identifying characteristics. They may look like tiny blades of grass, (the carrot is a good example), or they might be shapeless generic-looking leaves.
Let’s confine ourselves to vegetables in the Mustard Family, the Brassicaceae, crucifers such as broccoli, Brussels sprouts, cabbage, and kale. These plants are closely related (they are all variants of a single species, Brassica oleracea) and they share a common ancestor, a wild cabbage which still grows in Mediterranean coastal regions . After thousands of years of human selection and breeding these plants have assumed the multiplicity of forms we are so familiar with, and we tend to take them for granted. It is good now and then to reflect upon the generations upon generations of diligent gardeners, mostly women, who developed these variations on vegetative themes.
When a broccoli or cabbage seed (or any others in the Crucifer family) sends up its seed leaves they all look about the same. The seed leaves are generally lobed blobby-looking leaflets, sometimes vaguely heart-shaped. At this stage it would be difficult to distinguish a cabbage seedling, say, from a kale seedling.
Once the seed-leaves have generated enough photosynthesized energy the seedling will push forth the second set of leaves, and these new leaves begin to give hints of the essential nature of the plant. Look at these two close-up photos of kale seedlings I took today. Notice the tiny teeth on the second set of leaves. The kale variety is a common one, Scotch Curled, and those teeth are the first manifestations of the character of the plant:
One advantage of stating seeds inside, or in this case, out on a porch, is that I can observe a plant’s development closely. I’m less likely to sprawl out in a garden to watch the progress of seedlings directly seeded in a garden plot.
Kale easily withstands a frost and cold weather improves its flavor. I can imagine the garden in November, gray and tattered frost-killed remnants of the tropical vegetables, such as tomatoes, basil, peppers, and eggplant, contrasting with the deep green of kale and Brussels sprouts thriving in the sort of weather they prefer.