Lily Palokangas
Albert Lea Seed Horticulturist
MNLA Certified Professional

It’s that time of year again! Time to pick out your sweet corn seed for the season ahead. But first, we should revisit one of the most common discussions around sweet corn: the two groups they fall into. Read on to learn more about Su1 and Sh2, the two primary groups of sweet corn, and how those groups impact your planting plans.

What are the two groups of sweet corn?

The two groups of sweet corn are Su1 (SE, SYN, Quadsweet and SU—more about that one later) and Sh2 (all of the varieties we carry in this group are Sh2). These two groups must be isolated from each other (and other types of corn) or there is a big drop in quality. Below is a fantastic chart, courtesy of Crookham Seed (the people we get most of our sweet corn from), that shows this division.

Do I need to isolate my sweet corn by group?

Essentially, our Sh2 varieties—Solstice and Enchanted—need to be isolated from varieties in the SU1 group. NK-199 also needs to be isolated from the others because it has the original SU gene. Even though it is also in the SU1 group, its older genetics don’t play well with the newer varieties. All other varieties can be planted together.

Is there a catch or anything else to watch out for?

There is a catch to this. If you want the highest possible quality sweet corn, you should isolate ALL different varieties of sweet corn from each other. Planting an SE and a SYN together is fine, and the quality will still be good, but it can change your expected outcome a little.

Do I need to isolate by color?

Also, color isolation needs to be considered. If you were to plant Bodacious (an all-yellow SE) with Illusion (an all-white SYN) the eating quality would be great, BUT your Illusion crop will end up bicolor or mostly/all yellow. Similarly, an all yellow can influence the color of bi-color varieties too. Yellow is a dominate trait.

Ok, so how do I isolate my sweet corn?

You can isolate by distance or by time. If you’re growing sweet corn, isolate it by 250 feet. Easier yet is to isolate by time. This means that you are spacing out your planting times by 14 days to help ensure that the different corn plants are hitting maturity at different times. This dramatically reduces the chances of pollen from the wrong parent being present in the environment.

If you have any questions or want some advice on selecting the right sweet corn seed for your farm or garden, please email me at lily@alseed.com or give us a call at 800.352.5247.

So close! You can almost taste that sweet corn now.