Looking through seed catalogues to pick the best variety can seem overwhelming. They use non-intuitive terms and abbreviations like su, se, supersweet, or synergistic. These terms simply refer to different types of corn, categorized by their genetics.
Why does that matter? It matters because most types of corn need to be isolated from the others to avoid cross pollination. When two different genetic types of corn cross pollinate, it often results in an unpleasant, starchy ear of corn.
I'll explain the different types of corn to help you pick the best variety to grow in your garden this year.
Why corn is different than other garden vegetables?
When we eat corn kernels, we are actually eating the seed of the plant.
Most other fruit & vegetables are eaten for the flesh, like tomatoes or zucchini. This distinction is important because of how pollination affects the seeds of a plant.
Most fruits and vegetables can be pollinated by any other variety of that plant. If an open-pollinated tomato gets pollen from itself or the same variety, the flesh develops as expected and the seeds will produce exact replicas of the plant.
However, if the tomato flower is pollinated by a different tomato variety, the tomato develops into the exact version we planted. We eat it and it tastes as expected. But the seeds in that tomato are different and would not produce the same tomato if planted the following year.
Types of sweet corn
Sweet corn came about from a genetic variance from field corn (used as animal feed). The oldest type is referred to as Standard (su) corn, and newer types of corn are variations attempting to improve the sugar content and shelf life.
The various genetic types of sweet corn are as follows:
|Standard sugary (su)||excellent||medium||creamy||1-2 days|
|Sugary enhanced (se)||very good||high||creamy||4-7 days|
|Supersweet (sh2)||good||very high||crunchy||1-2 weeks|
|-- Synergistic (sy)||very good||high||creamy||1-2 weeks|
|--Augmented||pretty good||very high||creamy||1-2 weeks|
You can plant different varieties together within the same class, but avoid mixing classes.
Best flavor, shortest shelf life, 8% sugar.
This is the variety grown in the 1900s that is the source of the saying "have a pot of water boiling before you pick the corn." It loses about half of its sugar content 24 hours after harvest. But the flavor is worth it! It has an old-timey, heirloom corn flavor with a creamy texture.
This standard sugary corn is actually a great option for gardeners for several reasons.
- It's rarely sold anywhere, including farmers markets (due to the short shelf life)
- Excellent flavor and creamy texture
- It germinates very well, even in slightly cooler temperatures
- If left on the stalk too long, sugars convert to starch making it lose quality
- Loses 50% of sugar 24 hours after being harvested
Standard (su) varieties
|Butter and sugar||Bicolor||Mid|
|Honey & Cream||Yellow||Mid|
"Golden Bantam for me. I’ve grown Incredible and it is a fine modern sweet corn but nowadays all you can buy is the sugar enhanced stuff. Old fashioned varieties have more corn flavor to my palate and if you don’t have Amish farmers to buy sweetcorn from you have to grow your own for the experience." - alan, GrowingFruit.org
Sugary enhanced (se)
Sweeter (16-18% sugar), longer shelf life, but less flavor.
This type of corn was released in the 1970s but didn't gain traction until the end of the century while farmers waited for disease resistant varieties. It is twice as sweet as standard sugary (su) corn with a slightly longer shelf life.
You can find this type of corn at farmers markets, or grow it in your own garden:
- Sold at farmers markets
- Very good flavor and creamy texture
- Good germination rates, even in cooler temperatures
Sugary enhanced (se) varieties
|My Fair Lady||Bicolor||Early|
|Peaches & Cream||Bicolor||Mid|
"After testing at least 50 varieties of corn over the years, I keep coming back to Incredible. Big ears and great, not too sweet, corny, taste." Chikn, GrowingFruit.org
"This year I planted se+ hybrids Trinity (68 days) and Delectable (80 days). I was impressed with the complete pollination of these two hybrids even with the early stuff. The flavor was better on the longer season corn. And overall they were good. But I never had any that got to the “chewy” stage." - Levers101, GrowingFruit.org
Supersweet / Shrunken (sh2)
Even sweeter (35% sugar), longer shelf life, less flavor.
Another type of corn released last century, farms started replacing their standard sugary crops with supersweets due to the long shelf life and ease of shipping. It's no surprise then, by the early 2000s grocery stores sold this type of corn almost exclusively.
Supersweet corn is even sweeter than sugary enhanced. This type of corn converts sugars to starch very slowly, so it has a much longer shelf life. The downsides are the corn flavor isn't very prominent and the kernel skin is tougher.
It can also be a bit fussy to grow in the garden. The sh2 gene reduces the starch in the kernels, providing less energy for the seed to germinate. Supersweet corn seeds need slightly warmer temperatures to germinate and can have poor germination rates.
Considerations for growing at home:
- Very sweet, but less flavorful
- Crunchier kernel skin
- Long shelf life - great if you don't eat corn very fast - can last 2-3 weeks in the fridge
- Poor germination
Supersweet corn is also called Super Sweet, Super-sweet, Shrunken, or sh2.
|Honey 'n Pearl||Bicolor||Mid|
|How Sweet It Is||White||Mid|
|Illini Xtra Sweet||Yellow||Mid|
|Northern Xtra Sweet||Yellow||Early|
"We've tried several different corn seeds over the years and this [Honey 'n Pearl] is the one my whole family likes the best. It's super sweet, tender kernels, long full ears, and it keeps well without turning starchy. Our favorite!" - Angela H, Gurney's
Synergistic (sy) / Triple Sweet
Kernels are a mix of supersweet, sugary enhanced, and standard.
Synergistic corn was developed to improve the flavor while maintaining the shelf life, by mixing different types of kernels on the same ear. The cobs have a mix of supersweet (sh2), sugary enhanced (se), and sometimes standard sugary (su).
They have more corn flavor than supersweet (sh2), with a creamy texture and a long shelf life.
Synergistic corn will be abbreviated as sy or syn, and sometimes referred to as Triple Sweet or Quad Sweet.
Considerations for growing at home:
- Very sweet, with more flavor than supersweet (sh2), but less than standard (su).
- Creamy texture
- Long shelf life
- Good germination - similar to standard (su) and sugary enhanced (se)
|Big N' Tender||Bicolor||Mid|
"If you like really sweet corn, you should try honey select. We cut off the cob and freeze every year and when we have dinners people swear we must add a little sugar, but we don't. I have grow many varieties but settled on honey select." - Drew51 GrowingFruit.org
An improvement on supersweet.
This type is also an improvement on the supersweet (sh2) variety, but in a different way than synergistic (sy). Instead of mixing different types of kernels, this one is 100% sh2 kernels but some of them also contain the se/su traits.
This improves the flavor slightly, while maintaining the sugars and shelf life. The kernels are also more tender than the crunchy supersweet (sh2) varieties.
Due to the more fragile nature of the kernels, they need to be harvested by hand. This isn't a problem for home gardeners, of course, but it makes this type of corn unattractive to farmers.
Considerations for your garden:
- Very similar to supersweet (sh2) but with a more tender kernel
- Long shelf life
- Poor germination (similar to supersweet (sh2))
Augmented supersweet varieties:
Some sites and seed catalogues list these under supersweet (sh2) since they are augmented versions of those.
"[Yellowstone has] beautiful 8 inch long ears and just the right amount of sweetness, I couldn't have chosen a better tasting corn. I enjoyed it." - review on Gurney's
Yellow vs white vs bicolor
You'll find sweet corn seeds in yellow, white, and bicolor (where ears have both white and yellow kernels). Yellow corn has more beta carotene, but that's where their differences pretty much end.
Both yellow and white varieties are equally sweet. I know, there are a lot of people who firmly believe white corn is sweeter than yellow, or that yellow is sweeter than white. But their sweetness is controlled by the genes discussed above (su, se, sh2), not the color.
Why isolation matters
Since corn kernels are seeds, they need to be pollinated by other corn with similar characteristics in order for them to taste as you expect. These characteristics are controlled by specific genes, which are classified as the different types of corn discussed above (su, se, sh2, syn, and augmented).
Most genetic types of corn need to be isolated from each other. Isolation usually requires planting 250 feet apart, or for the pollination phase to be 2-3 weeks apart. Without isolation, specific genes mix and the resulting ears of corn can be starchy and unpleasant.
Sweet corn also needs to be isolated from field corn and pop corn.
Within each genetic type of corn, there are countless varieties. As long as those varieties are all of the same genetic type, they can be planted together.
However, I actually advise that you plant only one single variety so you know exactly what you are getting. Planting two different varieties of the same type will yield tasty ears of corn, but cross pollination will make them a hybrid of the two - you will no longer be able to distinguish the individual characteristics of either parent.
Here's an example:
- If a Bodacious variety is pollinated by another Bodacious variety, you will get an ear of corn filled with 100% Bodacious kernels.
- If a Bodacious variety is pollinated by an Incredible variety (same genetic type, different variety), you will get a hybrid of Bodacious and Incredible. So while the descriptions of both sounded good, now you are tasting neither, but instead a hybrid.
If you are interested in a more genetic explanation, including the dominant and recessive genes, Emmalea Ernest's artcile, "A Review of Sweet Corn Types and Isolation Requirements" explains it clearly and concisely, along with her chart on isolation requirements below.
The best corn to grow
I've grown the sugary enhanced (se) and supersweets (sh2) in the past, and they definitely taste great homegrown (better than grocery stores). However, I found that corn from the farmers markets (likely sugary enhanced) were almost as flavorful.
Standard (su) corn has superior flavor and excellent texture. It's only drawback is the rapid loss of sugars, which I honestly don't see a real problem as a home gardener.
That said, you have to eat it all so quickly that you get a very short season to enjoy the corn you've grown. This is where succession planting or growing an early & late season variety together can really pay off.
This year (2023) I am growing the standard (su) corn, Golden Bantam Improved.
If you prefer a sweeter corn with a longer shelf life, try one of the other types.
You can purchase the varieties listed in this article from Territorial Seed, Baker Creek, Victory Seed, Burpee, Gurneys and many other sources. I get a small commission from some (but not all) of those vendors if you click those links. Burpee and Gurneys have higher prices, so keep an eye out for their coupons and special offers if you shop there.