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After my kids and I sprouted seeds to see what the process entailed, we decided to carry out a series of seed experiments to learn more about seeds. Our seed experiments were designed to answer questions about what kinds of conditions seeds grow best in.
In a previous post I shared the results of our first seed experiment that asked the question: “Do seeds need light to grow?“
In this second experiment we addressed the question: “What temperature do seeds like?“
Note: For more seed activities your kids will love, see my Botany Unit Study page.
When conducting a scientific experiment, it is important to set up your conditions so that the only difference between the conditions is related to what you want to test. Because we wanted to test how seeds grow in different temperatures, it was important that all of the growing conditions for our seeds be the same EXCEPT for the temperature.
We started with two plastic cups. We placed equal amounts of dirt in each cup, and labeled one cup “cold temperature” and one cup “room temperature.” To both cups we added three different seeds: a broccoli seed, a lettuce seed, and a pea seed. (The seeds were part of this set of heirloom seeds I purchased.)
We placed the “cold temperature” cup in the produce drawer of our fridge. We placed the “room temperature” cup on our kitchen window sill.
When the dirt grew dry, I added more water as needed. In the week we waited before checking on our seeds, I had to add more water to the “room temperature” cup several times. However, I never had to add more water to the “cold temperature” cup as it remained very wet throughout the experiment.
After one week, we compared how the seeds in our “cold temperature” and “room temperature” cups had grown.
In the cup that had been kept at a cold temperature (on the left in the picture below), none of the seeds had begun to sprout after one week. In the cup that had been kept at room temperature (on the right in the picture below), both the broccoli and the pea seeds had begun to sprout. The lettuce seed, for some reason, had not begun to sprout yet.
So with this information, how would we answer our question “What temperature do seeds like?”
We learned that seeds seem to prefer the warmer temperature of a room rather than colder temperature of a fridge. Most likely, the cold temperature of the fridge makes the seeds believe it is still winter. Seeds seem to have a built in mechanism that makes them wait for warmer temperatures before sprouting, thereby giving the resulting plant the best chance at survival.
More resources for learning about seeds
More posts about seeds from Gift of Curiosity:
- Books about seeds
- Exploring seeds from packets
- Exploring seeds from nature
- Sprouting seeds
- Seed medallions craft
- Experiment: Do seeds need light to grow?
- Experiment: Do seeds need air?
- Experiment: Do seeds need their seed coat?
- Experiment: What liquids do seeds like?
For more seed activities your kids will love, see my Botany Unit Study page and my Botany & Gardening Pinterest board.
Follow Katie @ Gift of Curiosity’s board Unit Ideas: Botany & Gardening on Pinterest.
Wouldn’t the seeds in the fridge also be without light and fresh air? I wonder if there is another way to test temperature without added variables.
*smack forehead* Yes, you are absolutely right! That is a weakness in the design of our experiment, for sure, and one I failed to fully consider. They do get some light when the fridge opens and closes, but likely not enough to make a big difference.
This design flaws not withstanding, if you compare the results of this experiment to the results of the experiment where we looked at whether seeds need light, the results were quite different. This suggests that temperature, not the lack of light, was the main reason the seeds did not sprout.