Popcorn is currently one of America's favorite snack foods. However, it has been cultivated for several thousand years. Popcorn is one of the oldest types of corn, with some types dating back to 3600 BC. There are two main types of popcorn: pearl and rice. Pearl types have smooth and rounded kernels, while rice types have more elongated kernels with pointed tips. There are also miniature popcorns that are primarily grown for decoration. In addition to the variation in kernel shape, popcorn varieties are available in red, pink, blue, yellow, white, and multi-colored ears.
Popcorn is grown for its tasty, exploding seed. Heating the kernel converts the moisture inside the kernel to steam and forces the starch to turn the seed inside out. The quality of the end product depends on conditions during growing, harvest, and storage.
Growing | Harvest | Storage | Varieties | More Information
Growing
Planting
Several different varieties are available to home gardeners. Be sure to select a variety that will mature in your area before the first frost. Sow seed directly in the garden in spring about 1 to 2 inches deep, or somewhat more shallowly for varieties with small kernels (in Iowa, this is typically done in the first half of May). Plant them in several rows, laid out in a square or rectangle that isn't too narrow. This ensures good pollination. Space the rows between 30 and 36 inches apart to facilitate easy weeding and harvest. Thin as recommended on packet directions or to about one plant per 10 to 12 inches.
Isolation
Do not plant sweet corn in the same garden as popcorn. The quality of the sweet corn will be reduced if it is cross-pollinated by popcorn. Corn types can be isolated by distance, providing at least 300 feet between the types. They can also be isolated by staggering the plantings to ensure they are not flowering (tasseling) at the same time.
Care
Weed regularly and water as needed. Popcorn should be provided about one inch of water a week either by Mother Nature or the gardener. Watering should stop once the ears have filled out and are fully mature to allow the plants to dry. Any serious stresses like drought or flooding can greatly reduce yields and the quality of the popcorn.
Like other types of corn, popcorn has high fertility requirements to produce good yields. Before planting, conduct a soil test and use the results to apply fertilizer. Provide about 0.2 to 0.3 pounds of actual nitrogen for every 1,000 square feet. (For example, to get this rate of nitrogen, apply 2 to 3 pounds of a 10-10-10 fertilizer). Once about 1 foot high, side dress the rows with 0.1 to 0.2 pounds of actual nitrogen for every 100 feet of row (1 to 2 pounds of 10-10-10 fertilizer).
Harvest
Allow the kernels to dry on the ears in the field as long as possible. When harvested, the kernels should be hard, and the husks and shank completely dry. Many varieties will be ready to harvest by mid- to late-September.
After harvest, remove the husks, place the ears in mesh bags, and hang them in a warm, dry, well-ventilated location away from rodents. The ideal moisture content for popcorn is between 13 and 14%. Once or twice a week, shell a few kernels and try popping them. When the test kernels are popping well and tasting good, shell and store the rest of the kernels. To shell popcorn, rub the kernels off the cob with your hand while wearing a heavy glove. If the popcorn is "chewy" or the popped kernels are jagged, it is too wet and needs to continue drying.
Storage
Store the kernels in sealed, airtight containers, such as glass jars with tight-fitting lids. If stored properly, popcorn should retain its popping quality for several years. Unshelled corn should be stored at 40°F and 40% relative humidity. The storage location should also be rodent-proof.
If stored popcorn fails to pop, it may be too dry. Add one tablespoon of water to a quart of popcorn. Cover and shake at frequent intervals until the popcorn has absorbed the water. After 3 or 4 days, test pop a few kernels to see if it is ready. Add more water and repeat the process until the popcorn pops well.
Varieties
Below is a listing of a few readily available popcorn varieties, sorted by maturity time. Select a variety with the desired kernel color that will mature before the first frost. Seed sources include Rupp Seeds, Stokes Seeds, Harris Seed, and Johnny's Seed, among others.
| Variety | Color | Days to Maturity |
|---|---|---|
| Tom Thumb | Yellow | 85 |
| Early Pink | Light red | 90 |
| Cherry Berry | Dark red | 98 |
| Strawberry De-Lite | Multi-colored | 98 |
| Mini Blue | Dark blue | 100 |
| Cutie Pops | Multi-colored | 100 |
| Top Pop | Yellow | 100 |
| Robust R128YH | Yellow | 103 |
| Gourmet Mushroom | White | 103 |
| Robust 400MR | Yellow | 103 |
| Robust 98114W | White | 104 |
| Shaman's Blue | Purplish blue | 105 |
| Robust 997 | Yellow | 112 |
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