Watching baby plants grow up!

May 15

Garden Week Eight 5/15/2018

Watching Baby Plants Grow Up!

It is always such a treat watching seeds become plants. But what makes up a seed and becomes a seedling? We know that the genetic material of a male and female plant comes together to create a seed. But what does that seed look like and why do we want to know?

First let’s look at the anatomy of seeds and seedlings:

Testa or Seed coat: This outer coat protects the seed from the dangers of insects, bacteria and fungi. Along the seem of the seed call the hilum, we find the micropyle, which allowed fertilization of the seed and later allows water to the embryo starting germination process (we might think of this as a belly button).
Radical or Tap root: Becomes the first root and provides the seeds first underground support.
Hypocotyl: Provides support between the Plumule and Radical and becomes the seedlings stem.
Epicotyl: The embryonic shoot, which the first structure to break the ground, located above the Cotyledon, and produces the first leaves. These first leaves do not resemble the second or true leaves and will fall off.
Plumule: The first true structure of the plant, where the first true leaves will grow.
Cotyledon: Produces the first leaves and can (in some plants) work like an embryonic sack providing initial nutrients to growing seedling.

What does all this mean and why is it important?

Plant seeds: Vary in size and shape

We now know that water must get into the seed to start germination. We can see how small and fragile this structure is. And, we understand why we plant seeds in loose soil; to allow water and oxygen to access the inside of the plant and germinating the seed.

When planting seeds, we can consider placing the radicle or tap root in a downwards position. This cuts down on efforts to stabilize the future plant and allow energy to be used efficiently. Additionally, the stem structures will have the energy to force through the to the surface allowing the first leaves to start collecting sunlight for photosynthesis. For many seeds placing the tap root down is not possible, nor necessary as the plant seeds are too small.

As the seedling is pushing to the surface, keeping the top soil moist will allow the first leaves and stem structures to push through to the surface more easily, allowing more energy to grow the plant.

I have heard gardeners in the past say that sprouting in the dark is preferable. However, I think that the sooner the first leaves can get sunlight, the sooner they can create new energy for the growing seedling.

I don’t know about you, but I feel like I am back in school after today’s article. I won’t be handing out any homework assignments, but maybe you will look at your seedlings a little differently this year.