You can also gather plants to get food (and seeds.)
The seed stockpile should be seeds only to prevent other food from taking all the space.
I would make that 6x9 plot into 9 1x6 plots so you can plant other crops. You can tell if a farm plot has been planted because the wavey lines turn straight. A square ready for harvest will show a symbol for the plant. Squares that didn't get harvested in time will show a different grey symbol.
You might set the "All harvest" option until you have enough food.
Turn on the seasonal autosave feature for an unmissable reminder to update your farm orders. You can also set orders in advance, but if you don't have the seeds that wont help.
Digging channels into soil from outside will give you an outside farm that won't be plagued by planting/harvesting interuptions. (Really just needs to be plantable and labelled as outside, muddy granite on the very bottom z-level would work.)
Oh, and seeds can also be got and requested from trading and are usually cheap. Food too, but not as cheaply.
Recap:
Places to plant
Seeds/spawn to plant
Orders to plant them
People to plant them
People to harvest them
Small seed only stockpile nearby
Larger food stockpile nearby
Barrels and bags
Don't use up all your edibles for other purposes
Edit: Don't cook raw edibles until you have a stockpile of those seeds
[ December 05, 2007: Message edited by: Ziusudra ]