Sweet Corn – the only crop measured in knees…

 There are lots of different vegetables that the prairie vegetable grower can cultivate, regardless of their scale and experience. However, I’m not sure that there is any other vegetable that tops sweet corn in terms of collective desire.

Almost everyone loves sweet corn. Of course, I know of at least one person that DOES NOT, but he’s … unique. But my F-I-L aside, most people love sweet corn. It is one of those summer vegetables many people try to grow, year after year, but are often underwhelmed or downright disappointed with the results. For decades, I’ve had an intriguing relationship with this crop, as well as the associated opinions that accompany it. I have grown it when I was a summer student. I have grown it personally, with mixed results. And, by mixed results, I mean that I might get a crop 1 year in 10 if I’m lucky. I know that I’m not alone in this, but that is shallow comfort.

What does sweet corn really want?

One of the main challenges with this crop is that it has some specific requirements for growing. As a grower, you can do everything right, but the primary element that this crop needs is entirely beyond the average (non-godlike) person’s control in providing. Corn loves heat. It needs water and fertilizer and lots of sunshine, which you can supply with proper placement and effort. But it craves HEAT. And that isn’t necessarily something that you can provide.

Corn doesn’t grow at temperatures below 10°C, which means that there can be days upon days where the corn will just sit there. It used to be that you would put the seed in the ground and hopefully it would start to grow. Cool soils and cold temperatures increased the risk of things just rotting in the soil. If things went well, it would warm up and the corn would grow. Improvements in varieties has meant that some types can handle the cooler soils a bit better than the older stuff, but corn is still corn and it needs heat to grow when it is up and out of the ground.

The old adage “Knee high by the 4^th of July” is an interesting indicator, which is reasonably accurate. It gives you a decent sense of whether the crop is going to make it to the finish line in the time that is left in summer. This year, we’ve had plenty of heat and it looks like corn might have a good shot, provided it has the moisture and nutrients. In other years, not everywhere gets the heat units that are needed, and the corn doesn’t make it across the finish line.

Corn is wind pollinated, so you must take that into consideration when laying out rows. You will have to separate different types by a fair distance, since some cross-pollination can result in negative quality results in some types.

What is the best variety?

Ok, so here is where some of my experience-based opinions and prejudices might flare up a titch. I grew up in Saskatchewan and spent an extended amount of time studying and working at the University of Saskatchewan. It was during my time there that I was first exposed to the vast array of different sweet corn varieties out there. Each summer, in the vegetable research program, we’d plant many different varieties of sweet corn (usually well over 100). We’d carefully tend them all summer long, and if (BIG IF) we had a reasonably average year or were particularly lucky, towards the end of the summer we’d start to harvest delicious cobs of corn. The better the summer (e.g., warmer), the more varieties would make it to harvest. As with any variety trial, you will find the quality lands upon a broad spectrum, ranging from “Wow, that is NOT good, AT ALL!!!” to “I would eat that raw, it’s so good”. My point is that there are lots of good quality varieties out there, with a wide range of maturity dates. Breeding has resulted in some excellent quality sweet corn varieties.

However, in school and then when I moved to Alberta, I ran headlong into the deeply entrenched opinion that the “best” corn came from Taber. If it was labelled “Taber Corn”, that’s what you wanted. I would often get asked about where someone could get the variety “Taber” or the variety of corn that they grow there. Don’t get me wrong, the folks in Taber don’t just grow exceptionally tall farm boys and big potatoes. They grow excellent quality sweet corn. Their reputation is well deserved. But Taber corn isn’t a variety. It is several different varieties that are grown in excellent growing conditions by skilled and experienced farmers.

The fact is, you can grow good corn almost anywhere, provided you have a decent growing season length and good heat. Locally grown corn is often the best quality, simply because it is fresher and has travelled less distance to you. Improvements in varieties through breeding has meant that newer varieties and types will hold their quality for longer after harvest, but fresh is fresh. So, if you can find a variety that has the characteristics that you want/need, and you can grow it locally, that’s going to be the best. And chances are, it is something that the fellas from Taber are also growing, since they know good corn.

What is the difference between different types of corn?

There are several different types of sweet corn out there. Varietal improvements have resulted in corn that can tolerate cooler soils and that hold their quality better after harvest. The following table is one that I use to help keep the different types straight in my head. Maybe it’ll help you to narrow down what you are looking for.

Any tips for getting a crop off?

Other than choosing a good quality variety that will mature in your average growing season and then praying for some good heat, what else can you do to try and tip things in your favour?

You can theoretically start corn from seed indoors and then transplant out the plants when things warm up. In reality, this method doesn’t work all that great. Corn doesn’t really love being transplanted, and will likely go into shock for a time, stalling growth and undermining your acceleration efforts.

You can plant corn under a plastic mulch, particularly one that will warm the soil. The key is to have the seeds come up through the holes or you need to remove the mulch when the plants start to emerge. The mulch will have to be tight to the soil so that the emerging seedlings can find their way upwards and outward (if planting through holes). Unfortunately, you would need to have warm air when they get up above ground.

You could use row or field covers to warm things up a bit, but that is also a bit tedious. The growing points are below the soil surface for a time, so the floating covers will be fine early on (meaning they won’t beat the crop to pieces), but you can’t use it later on.

Did I mention praying?

Good luck.