Flint Corn Seeds - Japanese White Hulless Popcorn

Minimum Seeds per Packet: 140

Packet Weight: 21g

Planting Season: After Last Frost

Sowing Method: Direct Seed

Seed Depth: 1"

Direct Seed Spacing: 3"

Soil Temperature: 65-85 ℉

Days to Sprout: 7-10

Mature Spacing: 8-12"

Sun Requirement: Full Sun

Frost Tolerance: Frost Sensitive

Days to Harvest: 85

When to Seed Corn

Corn should be direct-seeded into the garden after your last frost date. It will germinate best in soils that are 65 degrees Fahrenheit. When deciding the best time to plant, be sure to check the days to harvest information for your variety, as many varieties need a long season.

Where to Plant Corn

Choose a spot with full sun and well-draining soil. Corn will have to be planted in a block to ensure consistent germination, rather than planting in rows like you would for other crops. You’ll have to grow at least a 3x3 block at minimum. Choose a spot where this planting method will be suitable. 

Cross Pollination

Corn is one of the few crops that will cross pollinate in the first generation, meaning that they can present genetics of different corn varieties in the first season. It’s not uncommon for popcorn and sweet corn to cross, resulting in not-so-tasty sweet corn and unpoppable popcorn. For this reason, you’ll have to be mindful of what other corn is being grown by your neighbors. However, if you’d like to grow multiple varieties - no problem! Simply time them by planting them two to three weeks apart so that they are tassling (pollinating) at different times.

Growing Corn

Plant seeds ½ to one inch deep and three inches apart. Ensure that rows are at least 12 inches apart. As the seeds germinate and grow (typically once they reach four to six inches tall), they can be thinned to eight to 12 inches. Once they’re about 12 inches tall, fertilize them with a high nitrogen fertilizer. 

Harvesting Corn

Harvesting corn is different depending on what type you’re growing. Sweet corn is usually ready about three weeks after the plants tassel. Keep a close eye on your corn patch as the ears grow. The harvest window for sweet corn is usually just a couple of days. Test for ripeness by peeling back the husk and puncturing a kernel with your fingernail. If the juice that comes out is white, the ear is ready! If it’s clear - it hasn’t quite reached its peak yet. 

Dent, flint, and popcorn ears should be left on the plant until the husks have turned completely brown. Ideally you can leave them on the plants until they are completely dry, but if you have lots of rainy weather predicted for the late summer or early fall, it may be best to bring the ears indoors so they can dry.

Corn (Zea mays) is wind-pollinated, so it can be tricky to prevent cross-pollination. A mile of separation is recommended for crops that are tasseling/silking at the same time with no barriers in between them. If your property is surrounded by windbreaks like trees or tall buildings, such distant separation is probably not necessary. Isolation can also be achieved by timing your plantings so that corn of one variety is finished being pollinated by the time the next variety begins tasseling. Or, if you can’t be sure of isolation any other way, you can place bags over the shoots (developing ears) you want to save, and hand-pollinate them when the silks emerge. Sow True carries corn shoot and tassel bags in our garden supplies section. Corn seeds will only be viable if left on the plant to mature completely. The husks should be completely brown before harvesting corn for seed. Make sure you allow the ears to dry down completely before shelling the kernels off the cobs, and storing the seed in an airtight container in a cool, dark, and dry location.