What are the differences between the various types of sweet corn?

Standard (su), supersweet (sh2), and sugar-enhanced (se) are the three major types of sweet corn.  They differ in sweetness, keeping quality, and seed vigor. 

Standard

Standard sweet corn varieties possess the traditional sweet corn flavor and texture.  Unfortunately, the ears of standard sweet corn varieties retain their quality for only 1 or 2 days in the garden.  Also, standard sweet corn varieties don’t store well as the sugar is quickly converted to starch. 

Supersweet

Supersweet or shrunken-2 sweet corn contains up to twice the amount of sugar as standard varieties.  (The common name shrunken-2 is derived from the shrunken or wrinkled appearance of the dry kernels.)  Also, the conversion of sugar to starch occurs at a much slower rate.  As a result, supersweet varieties may be harvested and stored over a longer time period.  Supersweet varieties, however, do have some drawbacks.  Yields of supersweet varieties are generally lower than standard sweet corn.  Also, the seeds of shrunken-2 varieties are smaller than standard sweet corn varieties and germinate poorly in cold soils.  While standard sweet corn can be planted in late April in central Iowa, supersweet varieties should not be planted until mid-May. 

Sugar-enhanced

The sugar levels of sugar-enhanced sweet corn are between those of standard and supersweet varieties.  The soft kernel pericarps make sugar-enhanced sweet corn tender and easy to chew.  The harvest and storage periods of sugar-enhanced varieties are slightly longer than standard sweet corn.  It’s generally recommended that sugar-enhanced varieties be planted one week later than standard varieties. 

Synergistic

The newest type of sweet corn combines some of the characteristics of supersweet and sugar-enhanced sweet corn and is referred to as synergistic sweet corn.  Synergistic varieties have higher levels of sugar than sugar-enhanced sweet corn.  Their kernels are more tender than supersweet varieties.  Synergistic varieties should be planted later than standard varieties as their seeds  germinate poorly in cold soils.