my sweet corn is about 5 foot tall - tassels have appeared over the past week, but i have no sign of any silks or ears - any suggestions? am i being impatient?

In my experience the tassles form a week or two before the ears start to form.

thanks dave! i hope you're right! this is my 3rd year trying to grow corn (no luck the previous 2 years) - i am in Michigan zone 5b

3rd times a charm!

I'm in a similar zone, and I was able to grow a couple of rows of sweet corn in just an Earth Box. Each stalk only produced one or two ears, but it was still fun and tasty. Maybe a silly question, but do you have yours planted in adjacent rows so they can pollinate one another?

yes - i do - i have them planted in four rows that are about 6-7 feet long - so they are in a "group" - the 1st year, i did not do this; last year i did - and both years, the stalks never got more than about 3 feet tall and only very tiny ears with nearly no kernels - they are definitely growing better and taller this year - was just concerned that there are no silks yet - thanks for your reply/inquiry!

Corn is a heavy feeder, so I ususally side dress with some type of nitrogen rich fertilizer. I often hand pollinate to make sure all of the rows of corn kernels develop. The silks usually show up when the tassels are producing pollen. Before that you can see the beginnings of the little ears start to come out of the leaf base.