Tried searching for same type of bug but it seems only way older versions have had it.
After planting and letting potatoes / carrots / wheat grow, it seems on some farmland blocks they did not grow naturally over a considerable amount of time. Using bonemeal did however grow these plants too. Light level didn't seem to be the issue since all un-grown blocks seemed to have at least 8, and some blocks that HAD grown plants had even 7. Water also shouldn't be the trouble, same reason.
How to re-create: Light the place up. Plant a lot of stuff. Wait.
It is possible I've overlooked some growing conditions if there has been an update recently changing them, I haven't played in few months. But the system I've been using to grow plants has been same since official release and never had trouble. Please bear with me if this is just spam, my first (possible) bug to post about <3
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I feel kinda stupid now, I'll check wiki next time before writing right away. Thanks for the quick answer! Relighting and checking if that'll do.
http://minecraft.gamepedia.com/Tutorials/Wheat_farming
Simply place a torch on the wood right beside you on that screenshot.
Why there is wheat growing at light level 7 that's another story...