Abstract
Watching a plant grow is like magic for kids, but it can take a long time, and they can lose interest. The solution is to start down the path to a green thumb with a plant that is easy and quick to grow. It doesn’t get much easier than carrot tops.
- Minimum Age: 3 with supervision (cutting and pouring)
- Equipment Level: Stuff around the house
Introduction
Most plants grow too slowly for kids to notice. You can plant seeds and then be surprised when they finally poke through the soil, but in our house, the kids usually have forgotten about the project by that time. Carrot tops, however, are a growing project that provide daily entertainment. It may take them a day or two before they start, but once the first leaves appear, you can see and measure the progress each day. Carrot tops are especially interesting since you can get bushy greens with only water and light, though if you try growing one in the dark, you may be in for a surprise.
Materials
- A few carrots with at least a centimeter of greenery remaining at the end.
- Sharp knife.
- Cutting board.
- Flat bottomed container, either shallow or glass so light can get through (we used plastic party cups).
Instructions
- Cut the ends off of several carrots. Be sure to leave a centimeter or so of the edible part.
- Place the carrot ends in the container with the flat side down and the greens sticking up.
- Pour in enough water to almost cover the carrot ends.
- Place the container where it will get sunlight (or at least plenty of artificial light).
- Observe the carrots each day and watch how fast the greens grow.
- Eventually, you’ll see tiny roots growing out of the orange part. When they get about two centimeters long, you can transplant your carrot tops into soil to help them grow even bigger.
Results
Here’s what happened:
- The edible (orange) part of the carrot contained a lot of energy stored in the form of sugar. It also had the other building blocks needed to grow the greenery.
- When you added water and sunlight, the carrots had everything they needed to regrow their greens.
- Once the carrot tops had roots and leaves, they were ready to get their nutrients from soil.
Why do you suppose this one turned out orange?
Discussion
Not too shabby. With a little bit of work, you have begun your journey to getting a green thumb. There are many ways to grow a new plant, and what you just did is similar to a technique called “rooting”. You take a cutting of a live plant and help it grow a new set of roots. A skilled gardener can take a cutting from a live plant and root the cutting. That gives the gardener a new plant. That way they can expand their garden from their single starting plant. Scientists call it “propogation” when you increase the number of an organism that way.
You may be wondering why the greens grew but the tasty orange part of the carrot did not. The part of a carrot we usually eat is called a “taproot”, and once it has been cut off, it can’t regrow. Unlike fruit trees, which produce fruit that can be picked and eaten each year, you destroy the carrot when you eat it. If you want more carrots, you’ll have to grow them from seeds.
Now that you have a tiny forest of carrot greens, what will you do with them? I recommend getting some toys and learning about macro photography.
Going Deeper/What If
When you root a cutting, you’ll need some starting material. Even seeds are packed with endosperm which provides nutrients and energy to help the plant grow. Once a young plant has roots, it can gather its own nutrients, but until then, it needs a food source. That’s why you have to leave some of the orange taproot on your cutting. Without that, you probably won’t get much growth.
What about the greens? What if you cut them all off? Would anything grow? Give it a shot.
And what about sunlight? Seeds grow underground. Can the carrot top use the stored energy in the taproot to grow in the dark, or does it really need the extra light? That is another good experiment for you to try. (Spoiler: the one we grew in the dark grew orange leaves. When we left it in the sun, it turned green after a few days. When it was in the dark it didn’t make chlorophyll, which causes the green color, but it started making it once we put it in the light.)
What if the water contains something else? Will they grow in soda? Juice? Vinegar? Try them out. We tried the setup above and 4 variations.
Q: What’s another plant that is easy to root.
A: Spider plants. When they are happy, they put out little “babies”. You can pinch off a baby and put it in the top of a full bottle of water. Soon you’ll get roots growing down into the bottle. Plant it once you have good roots (5 – 10 centimeters long) and before long your whole house will be covered in spider plants. Unless you have cats, who love to eat spider plants.
Q: Can I leave them in water or do I have to plant the cuttings in soil?
A: Eventually the the taproot will run out of nutrients and the greens will stop growing. By planting them in soil, you are giving them access to the nutrients they need to keep growing. But what if you put nutrients in the water instead of putting the plants in soil? The answer is that they will grow. Such a growing system is called hydroponics, and it is the sort of system scientists are exploring for growing plants in space. Astronauts need fresh veggies too!
Q: Aside from taking fun photos, what else can I do with all these bushy carrot tops?
A: Have you ever thought of keeping a pill bug as a pet? Check out our pill bug project (coming soon). Carrot tops were our pill bugs’ favorite food.
Conclusion
Agriculture is hugely important. We all (should) eat lots of fruits and veggies. And if you eat meat, don’t forget that the animal your meat came from probably ate veggies. More importantly, plants breathe in carbon dioxide (CO₂) and breathe out Oxygen (O₂), so they help keep the atmosphere in balance and give us the oxygen that we need to survive. So remember: grow more plants!
