Plants With A Purpose
There’s very sweet corn and then there’s good corn.
Confessions of a heritage corn addict
Every spring I sow sweetcorn and it’s a non-negotiable task. No matter what else I have going on, it all falls to the bottom of the priority list. Corn is king.
As I sow, I can almost taste the hot, butter-covered cobs. I visualise the giant, healthy corn plants, reaching to the sky, their wavy leaves not quite concealing the swelling ears of corn, ripe with deliciousness. There’s not a pest in sight.
My heavenly vision is delightful, but the road to achieving it can be rocky. Our North Canterbury garden has a marginal climate for growing corn. Half the time my transplants are hit by frost, even as late as November.
If they survive that, they are likely to be bowled over in a good Nor ‘wester.
However, I have caught the corn bug. It’s a life-long affliction and I’m going to do my best to infect everyone.
I’m not talking about varieties like the the sickly super-sweet types. My corn is the fuller-flavoured, colourful, more adaptable heirloom varieties. You can taste the difference.
The first thing you need to know about good corn
My love affair with corn began in my teenage years on my family’s Hawkes Bay dairy farm. The crop was below the cowshed, and frequently sluiced with effluent when the shed was washed out.
All that manure and water meant we harvested barrowloads of corn. The plants grew to 1.8m+, producing fat, juicy ears. What we couldn’t eat off the cob was turned into delicious corn fritters.
By accident, I had stumbled on one of the keys to great corn. It likes fertile, deeply-dug, well-drained but moistureretentive soil in a sunny position.
Most corn plants will reach 1.2-2m high, depending on the variety and growing conditions.
But they’re all hungry for nutrients. It’s hard to overdo the fertiliser. It can be quite the challenge if you don’t have a cowshed uphill from your garden.
Dig in plenty of organic matter, as
corn will use it all in the three months or so it takes to mature.
Time and temperature
Corn requires a minimum of 12°C to germinate and its preferred growing temperature is 15-35°C. ‘Super sweet’ varieties need warmer temperatures for germination, a minimum of 14-16°C.
If sown when it’s too cool, seed will rot in the ground. This means if you’re sowing directly into soil, it is too cool until NovemberDecember in my Canterbury garden, or October in northern areas.
Germination can be erratic. Fresh seed is best as viability declines after a year. Sow seed 5cm deep, in rows 75cm apart. Thin to 30cm when seedlings are 5-10cm high. Plant or sow in blocks to aid wind pollination.
In our frost-prone Canterbury climate, I start the seed on a heated bed in our greenhouse, in cavity trays, as the roots resent transplanting.
The timing is tricky. Sow too soon and the young plants sulk in the cold or have to be held in pots too long before it is warm enough to plant out. I cover my bases and make several sowings (seed is cheap!) ensuring at least one of them will avoid the wind, frost or hail that may try to kill them.
Dig in plenty of organic matter at planting – corn is a greedy crop.