Friday, 22 June 2012

Corn 101

by Sadge, at Firesign Farm
I have some friends that wanted to grow some corn. Now, corn is easy to grow from seed (more about that below), but they were seduced by a couple of little six-packs of plants in the garden department of a local big-box store. They brought them home and carefully set them out in a nice little line at the back of their garden. The stalks grew tall and soon the tassel on top emerged, grew taller, and spread out into graceful fronds. Below, clusters of corn silk were seen at a couple of the junctions of leaf and stalk. My friends watched anxiously as the the growing cob pushed the silk out farther and farther, until at last it withered and turned brown. Time to pick their corn! But when they shucked the fresh ears, they were disappointed to find only a few kernels on otherwise bare cobs. What happened?

Corn "birds and the bees" time: ordinarily, corn is pollinated by the wind. The top tassel forms the pollen. If you rub your hands over a fresh tassel, they'll be covered with a tan dust; if you shake the tassel, you can see that dust falling and blowing in the wind. Down below, each strand of silk links to one kernel on an ear of corn. One speck of the pollen dust has to land on one silk strand to form one kernel. On a single line of plants, only the downwind ears might get pollinated, or depending on which way the wind blows, maybe none of them will completely.

So - how could they have fixed this? One way is to plant corn in a clump, block, or circle instead of a single line. The more chances those silks have to catch a speck of pollen flying around, the more chances your ear of corn will be fully filled in. Ofttimes I'll hand-pollinate my most upwind rows, just to make sure. I'll just rub my hands over a tassel and then dust them off right over the top of the emerging silk below. Or you can shake the tassels into a paper bag, and then pour that over your silks, or just bend the stalks over and shake the tops over the plants nearby.

I'll usually steer clear of corn seeds offered at seed swaps. Even though the corn might have been tasty on the plants those seeds came from, it's no guarantee that the seeds gathered last year will taste the same this year. A lot of sweet corn grown now is from hybrid seed, so those won't necessarily bear true the following year. And since corn is wind-pollinated, it's hard to keep the pollen from sweet, field, or popcorn separated when grown in a small garden space. If you want to save your own corn seeds, you'll have to either separate the varieties, or pick only one open-pollinated (not hybrid) variety to grow.

Sweet corn is best picked at its peak (when a thumbnail-punctured kernel oozes white milk - clear juice, you're a bit early; chunky solid, you've waited too long), cooked and eaten (or canned or frozen) right away. (I haven't tried this cooking method yet - click here - but I am intrigued and think the old guy doing the short video is such a cutie - check it out). Some hybrid varieties will now hold on the plant longer, but still, the sugars in corn turn to starch the longer you wait.

I like to stretch my fresh corn eating time into 6 - 8 weeks. One way to do that is to succession-plant your corn seeds - moving downwind, plant another row each week for a month or two. I find that difficult in my climate. The later planted seeds, germinating in warmer weather, catch up to the earlier ones that started out in colder soil. The latest ones, trying to get started in summer's withering heat, often suffer and don't do as well.

So, I plant all my corn at the optimum planting time for my climate - early to mid-June when the soil has finally warmed up. I dig little ditches and plant the seeds down in the bottom of those, and then run a length of chicken wire over the top - the ditches are deep enough to keep birds from pulling up the new sprouts. I hand-water into those ditches to make sure I get a good, fast germination rate, and once the corn is growing up through the chicken wire I take that off and fill the ditches back in (the soaker hose is already in place at the level the double-row wide-bed ends up being). The corn is now rooted deep enough that the birds can't bother it. Corn puts out extra feeder roots at the base of the stalk, so burying that gives them something to grow into - making them stronger against the wind.

To stretch my harvest time, even though everything is planted at the same time, I use the days-to-maturity information on the corn varieties. The most upwind rows average 65 days, the middle ones 80 - 85, and then the last rows 95 - 100. That's about the limit of my growing season, but it means I'm eating fresh-out-of the-garden corn from early-August until mid-September, and enough to freeze for wintertime soups and muffins - all easily grown from seed.