Photo: This corn is ready for picking.
The silk is dry and brown, and the kernels at the top of the corn have fully developed.
How can you tell when corn is ready to be picked? I wait until the silk of the corn has dried up and turned brown. Then I take my fingers and feel around the tip of the corn. The tip of the corn should feel full. If it is pointy, then you can wait longer. If you are unsure, you can always peel back a bit of the husk to see if the kernels have fully developed to the top. However, please be aware that when you peel back the husk you are also are risking opening your corn to pests so if at all possible avoid doing this.
Once you have determined the corn is ready for picking, just grab the corn in your hand and twist it off the stalk.
Tip: Corn will start converting its sugars into starch as soon as it has been picked. To capture the natural sweetness of the corn, have the grill ready to go before you pick your corn and then immediately grill your corn after picking it. If you are growing sweet corn it is not necessary to immediately cook the corn. Sweet corn converts its sugars into starch at a slower rate than other corn.