For Earth Day last week, the girls and I read all about plants, grew a little pot of grass seed, and ultimately, started our own vegetable seeds. They thankfully have begun to sprout, and with that, came a flood of questions from Big M. How long will the rest take? Where did the green come from? How does it grow? So this week, we continued our How Does Your Garden Grow? studies, and created our own miniature greenhouse for a study of germination.
A Study of Germination
I have ZERO gardening experience, and beyond ‘they need sunlight, dirt and water to grow,’ I had no answers for Big M. I concocted this little experiment to answer the questions for the both of us. We would be able to watch to see both where the green comes from and how long the seed takes to sprout.
Cost: Less than $5
Prep Time: Less than 5 minutes (since we built it together)
Clean-Up Time: Less than 5 minutes
First, we prepared our seed environment. I separated a sheet of Avery Business Cards. We had these on hand for another upcoming project, but you could easily cut a piece of cardstock to fit your transparent, seed holder of choice. I used a card as a template to trace on the paper towel. And since Big M is all about scissors these days, I let her cut them out. You want to use a double or triple thickness of paper towel, as this will hold the moisture and serve as the dirt substitute for your seed.
PGPB Guru Tip: Don’t use a black washable marker like me to trace your template… it bled all over when we watered the paper towel!
Next, I helped Big M slide the paper towels into the lower half of our card holder. Then, we placed one or two seeds of each variety in with the paper towel, and affixed one of each seed to a business card with a glue dot. Once the lower seed germinates, we will still have an example of its original shape.
Once our seed environment was prepped, we worked on labeling our seeds. I told Big M she could draw a picture on the cards and I would help her label them. She wanted to line up all the seed packets with their seeds to use as inspiration. I cracked up when she told me she needed the ‘red too for the cucumber’ because in the picture on the package, there are tomatoes in the basket with the cucumbers!
Finally, we were ready to water our seeds and watch them germinate! We used a medicine syringe to add water to each pocket, so as not to oversaturate them, then hung them in our sunniest window.
It is important to keep your paper towels moist – the card holder serves as a mini greenhouse, so much of the moisture collects and remains inside the pocket, but you may need to add some water every 3-4 days.
Where Does the Green Come From?
As we patiently waited and daily checked our seeds for activity, I started explaining to Big M ‘where the green comes from.’ Without getting too technical, I explained to her that every healthy seed contains a baby plant, called an embryo. The embryo will grow into a seedling, breaking its hard seed shell, and sprouting roots and leaves. I told her it’s kind of like how the baby is growing in my belly – it started as an embryo and is growing into a baby.
How Long Does it Take to Grow?
We started our germination window seeds a week ago. By Day 3-4, the sunflower seed shells cracked and roots crept out. By Day 5, the peas showed signs of life. And on Day 6, the cucumber seeds began to sprout. We are still waiting on the peppers and pumpkins to do something. Also, one of the sunflower seeds has not sprouted. Big M wanted to know what was wrong with it. I told her not all seeds fully develop. Some don’t have a embryo inside and are empty. Note also that when the seeds are in dirt it may take a few more days to see sprouts above the surface of the dirt, from the time we were able to actually see them break their seed coats in our Germination Windows.
How Does it Grow?
So as it turns out, I was wrong when I told Big M a seed needs sun, water and dirt to grow… For a seed to sprout, or germinate, it needs three primary things: water, oxygen and temperature. The seed takes in water, which causes the dry, mature seed to swell and break its hard, seed coat. Inside the seed, in addition to the embryo, is also food for the seedling. Water helps breakdown this food into chemicals the seedling needs to grow.
Until its leaves form, the seedling also needs oxygen, just like people do, to continue to grow. It often gets this from pockets within the soil in which it is planted. Lastly, temperature can impact germination. Many seeds germinate at temperatures of 60-75 F, about room temperature, though this can vary greatly.
Once the seed breaks its seed coat and begins to form roots and leaves, it has typically eaten through the food supply stored within the seed itself, and now grows via photosynthesis, which requires sun, water and carbon dioxide from the air to feed the plant.
Our Germination Windows answered many of Big M’s questions and were fascinating to watch. She checks on them daily and takes everyone who comes over to our house to see them. If you enjoyed this post, be sure to check out our Kidmade DIY Garden Markers! Be sure to also follow our Pinterest boards: How Does Your Garden Grow? and STEM for Kids – Science for more great learning activities.