How to Grow Popcorn.

The Kernel

Discovery Experiment 

Learning Objective: Learn to grow popcorn kernels and watch them grow

Key Terms: Plant science, food science, popcorn, corn, pollination, planting

Grade Level: K-3

Materials

  • Store-bought organic or heirloom popcorn kernels (see our recommendation below!)
  • Thick paper towel or a piece of cloth
  • Water

Estimated Time: ~15 min to set up, then watch your popcorn grow each day

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Lesson Plan 

Popcorn Growing!

How to Plant and Harvest Popcorn?

What if I told you that you could grow, harvest, and pop your own popcorn right in your backyard or classroom. 

There is a profound sense of accomplishment and joy that comes from taking the time to grow your own popcorn and being able to pop in for a delicious snack. Follow along on with this discovery science experience that your kids won’t forget.

Picking the Best Popcorn Seed

There are 6 actually six different types of corn, each with its own unique characteristics that make a huge difference in how they are used. 

  1. Dent corn: The starchier of the corn and primarily used in animal feeds. 
  2. Flint corn: Similar to dent corn, it does contain a hard outer shell and most notability is recognized by its multi-colored kernels. 
  3. Flour corn: A yellow and starchy corn with a soft outer shell making it ideal to be ground into flour. 
  4. Sweet corn: If you are eating corn on the cob or a southern cream corn dish, then you are probably eating sweet corn. Most known for the sweet flavor it has to offer. 
  5. Pod corn: Not commonly grown for commercial use because each individual kernel is wrapped in small leaves, called glumes. This makes it difficult to process. 
(pod corn has a unique characteristic where it individually wraps each kernel)

Popcorn: Due to the perfect moisture to starch ratio, this is the only corn kernel that pops into the snack we know and love, popcorn! When the kernels are heated, the water inside creates steam that increases the pressure inside of the kernel. When the pressure gets too great, then the kernel bursts open into a fluffy treat. 

(four different types of corn)

You can present to your students the different types of corn through photos or if possible purchase different types of corn kernels so they can see the differences between the types of corn. 

Note: If you plan to transfer the popcorn plants to a garden, it is best to plant popcorn in the spring or at least when the soil temperatures average about 60 to 65 degrees. Planting them too early in the spring, the kernels can struggle to sprout and can lead to them rotting away. 

Pollination 

When planted popcorn kernels start to grow, they will produce both male and female flowers. This allows the corn to self pollinate by relying only on the wind to transfer the pollen from the male flower to the female flower. 

The male flower will grow from the top of the plant called a tassel. The female flowers are grown along the cob called silk. If the silk doesn’t receive any pollen, then the cob will not grow kernels on the cob. This is known as a skip. 

If different types of corn are planted too close together, this will result in cross-pollination. This hybrid corn will result in corn that isn’t quite sweet but also doesn’t pop. Keep different types of corn plants at least 50 ft apart from each other. 

(close up of the corn plant female parts known as silk)
(close up of the corn plant male parts known as a tassel)

Note: If planting outside in a garden, it is best to arrange the sprouts in a block-like fashion to allow for pollination to occur. Instead of planting 1-2 long rows, aim for 3-4 short and wide rows. Keep each kernel about 1 ft apart from each other.

Planting for Success

Corn relies heavily on the nutrients found in the soil. You can ensure that the soil contains the best amount of nutrients by adding a compost layer where the kernels can be placed about 2 inches deep. 

It is also important to ensure weeds are kept out of the soil. Weeds will rob the nutrients from the soil, leaving none left for the popcorn to grow. 

Depending on where you are in the country you will need to water your popcorn appropriately. Popcorn on average grows best with about 1 inch of water per week. If you live in a dryer environment, best be sure to water the corn to ensure the soil stays moist until popcorn stalks become established. If you live in a rainy, wet environment then watering can occur less frequently as long as there is rain!

Fertilizing your popcorn is not required, but it can help to promote a healthy popcorn crop. Using a balanced all-purpose organic fertilizer can be helpful. 

Discuss with your students what they think a plant needs to grow. For kids in lower grade levels (K-2), this can include talking about how water, sunlight, and the soil provide food for plants to grow. For higher grade levels (2-3), photosynthesis can be introduced to demonstrate how a plant uses water, sunlight, and soil to create sugar for foods. 

Harvesting 

Once planted, popcorn plants should start to emerge from the soil within 10 days. Popcorn plants will grow to about 8 feet tall. Before long, the plants will self-pollinate with the help of some wind.  

It will take approximately 90-120 days for the popcorn to reach full maturity. Allow the popcorn kernels to dry before removing them from the stalk. When the stalk and leaves turn brown and dry is a good indication that the corn is ready to harvest. 

Your students can measure how fast the popcorn plant grows each week as a fun addition to the experiment. Further create a sense of responsibility to have them help with keeping the garden free of weeds, watering, and fertilizing. 

Once the popcorn has been removed, it is critical to keep the popcorn cobs in a warm and well-ventilated area to allow the drying process to continue. Remember, the moisture has to be around 14% in the kernels for it to pop. 

Wire baskets or wooden baskets tend to work really well. Allow the popcorn to dry for a minimum of 4 to 6 weeks before removing the kernels from the cob. 

Note: The kernels can be removed from the cob by using a hand-held corn sheller or removed by hand. The kernels can be stored in a dry, airtight container for over a year. 

(image of an older version of a corn sheller)

Experiment 

Below are the steps you can take to grow your very own popcorn. If you don’t have space for an outside garden or it’s not the ideal season to grow popcorn, no worries! You can still complete steps 1 through 5, this will demonstrate how to sprout popcorn kernels. 

Directions 

  1. Dampen the cloth or paper towel with water.
  2. Place the dried store-bought kernels in a wet cloth or paper towel. 
  3. Lightly wrap the kernels. 
  4. Place the wrapped kernels in a warm and sunny spot. Sunny windows tend to be a great place to store the kernels. If the cloth or paper towel becomes dry, simply add a bit more water to keep it moist. 
  5. Within a week you can open up the cloth or paper towel. You should be able to see that they have sprouted. Note: If you check your kernels daily with kids, be careful not to tear any potential new spouts. 

Show the children that they sprouted a kernel and what that means. 

**Time to head outside**

  1. Prep your garden with an adequate amount of compose and moisture. 
  2. Plant the sprouted kernels in the soil about 2 inches deep and about 1 foot apart. Be sure to arrange the crop in short and wide rows. Note: Check your local growing zone to determine the best time to plant your sprouted kernels. 
  3. After about 3 to 4 months of watering and caring for the crop, the kernels should now be tall stalks. 
  4. Allow the kernels to dry on the stalk or until the stalk and leaves have turned dry and brown, 
  5. Now you can harvest your popcorn by removing them from the stalk.
  6. Place the popcorn in a dry, well-ventilated area for about 4-6 more weeks to allow the kernels to fully dry. 
  7.  Once dried, you can remove the kernels from the cob by hand or using a hand-sheller. 
  8. Time to POP! Heat the popcorn kernels in an air popper or over the stove just as you would with store-bought kernels. 
  9. Add your favorite toppings and enjoy!

Exploratory Ideas

Here are a couple of ideas of how you could take this experiment one step further. 

  • Compare store-bought kernels, microwave popcorn kernels, and kernels bought for gardening. Test to see if the kernels grow the same, differently, or not at all. 
  • Photosynthesis plays a crucial role in the growth of any plant. You can experiment with how the sun changes the speed of growth or sprouting by storing the initial kernels in a damp cloth in the sunlight or in a dark space. 

You can make it fun by challenging your kids by making a hypothesis or guessing which kernel will grow and why that might be. 

We Want to Hear About Your Experience

I would love to hear about your first popcorn-growing experience! Whether you decide to fully plant your sprouted kernels or just want a little fun experience for your kids to see a kernel sprout to life.

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