Every year, I tweak my method of growing sweet potato slips.  Year 1, we put sweet potatoes in partially filled glasses of water and they rotted, so year 2 we added a heat mat under the glasses.  The heat mat tempted several of the sweet potatoes to sprout, but I was disappointed at how late the slips showed up --- we didn't fill the last of our sweet potato beds until early July.  So, last year, I started the slips at the end of March...and the roots sat there until April, producing slips during the same time frame as they had the year before.  I also lost several tubers last year since I chose big roots that were less inclined to sprout.

This year, I made yet more changes to my sweet potato propagation method.  I chose tubers that were about two inches in diameter at the widest point and placed them beside the incubator for two weeks to preheat.  Monday, I dug about a gallon of small gravel out of an eroded wash above the alligator swamp and filled up a seed-starting flat, laying the sweet potatoes on their sides and then packing damp gravel between them.  I added the clear top on the flat to keep the contents moist and slipped a heating pad underneath to promote sprouting instead of rotting. 

In case you're trying to decide if sweet potatoes are worth growing, I'll throw some numbers out there.  Conventional wisdom, repeated all over the internet, holds that white potatoes give you the most calories per acre, but in our garden last year, we got just over 6 pounds of sweet potatoes per garden bed, which comes to 2,379 calories.  In contrast, we harvested 6.5 pounds of white potatoes from each bed, but the white potatoes have fewer calories per pound, so they lost the race at 2,034 calories per garden bed.

That said, the greatest number of calories I've ever harvested from one garden bed was a tie between a bed yielding 13.5 pounds of carrots fall before last and the 3.5 cups of amaranth seeds I threshed in the summer, both clocking in at just over 2,500 calories.  Clearly, white potatoes aren't the only high calorie food you can grow in just a bit of space.  I wonder which other oft-repeated tidbits of gardening lore aren't precisely correct?  The moral of the story is --- try several different kinds of high calorie crops and choose the ones that match your soil, climate, and taste buds.