Corn needs to be pollinated by the wind and if you do not have enough silks (the tassles) then you will get really low pollination so yes, it is true you need at least four rows of corn ten feet long for good pollination. This is why corn is not a good crop for a raised bed or a small garden. Also, rain stops the pollen from being blown by the wind so do not use over head irrigation (like a sprinkler) when the tassles are releaseing pollen. Another corny problem - corn is sensitive to frost so you must wait until late May or even June if you live where winters are long.