List of sweetcorn varieties
This is a list of the most commonly cultivated varieties of sweet corn, and the approximate number of days from germination of corn plant to harvest. Unless otherwise noted with the term "open pollinated," all varieties are hybrids. Genetically modified varieties only available to large-scale commercial growers, such as Bt corn and glyphosate resistant corn, are not listed. Standard ("su"). The oldest type of sweet corn contains more sugar and less starch than field corn intended for livestock. Tends to be heartier in respect to planting depth, germination and growth than other types. Begins conversion  of sugar to starch after peak maturity or harvest, and as such is best eaten immediately after harvest. Multicolor su. Multicolored varieties are usually at their sweetest when the mature color just starts to "blush" on the kernels. Sugary Extender ("se"). Contains even more sugars in relation to starch than su types, and as such is able to retain sweetness for 2 to 4 days with proper refrigerated handling. Somewhat less hardy than su types. Is known as a "tender" kernel and as such does not lend itself to mechanical handling. Does not require isolation from su pollen, although it  is preferred. Some seed catalogs don't distinguish the heterozygous se (one se parent) and homozygous se (two se parent) varieties, but if they do, the homozygous se varieties will be labeled either "se+", "(se se)" or "SE". Supersweet ("sh2"). Supersweet or shrunken-2 types have four to ten times the sugar content of normal sugar (su) types and with proper handling is able to be stored for up to 10 days. Less hardy than even se types, requiring higher germination temperatures, precise planting depth and isolation from all other corn pollen for optimum results. The name derives from the shrunken , shriveled appearance of the dried kernel which is low in starch. Synergistic ("sy"). Synergistic varieties combine differing genetics on the same ear. The first varieties developed of this type have 25% sh2, 25% se and 50% su kernels on the cob but now different combinations are possible. There is an increasing number of brand names and trademarks that cover specific genetic combinations under this general type. However, a common trait of all sy types is that isolation from other su and se varieties pollinating at the same time is not required, though isolation may still be recommended for maximum sweetness . Augmented Supersweet. Varieties of the augmented supersweet type combine multiple gene types on top of sh2. These varieties have 100% of the kernels containing the sh2 gene, but also have se and su genes in some portion of the kernels. The augmented supersweet varieties have tender kernels like the se varieties. Therefore, mechanical picking is not recommended. As with other supersweets, these varieties must be isolated from su, se and sy types pollinating at the same time to prevent starchy kernels.