Interesting way to start sweet potatos.

I work at a co op, and meet lots of interesting people. I learn a lot of interesting things.  Today I was talking with a gentleman, and he was telling me about his amazing sweet potato crop he harvested.  I told him I haven't tried S P yet.  He told me he had the best way to start them.  Buy the kind of sweet potato, or yam you like in the grocery store. Put it in a tray of soil  length wise, and  fill so the sweet potato is half in the soil and half out.  Keep the soil moist, in the house.  He said it will soon sprout eyes. Let it grow until your sprouts are about 6" long.  Remove them from the S P and put into water.  He says the sprouts grow roots.  At that point you can pot them, or plant them in the ground.  
This man swears by this method.  We live in Northern California zone 9 b, I have no idea if that makes a difference. I have not tried it myself.  I was sure when he was telling me he was going to say cute the S P when it formed eyes, so it surprised me when he said don't plant the S P.  I don't normally share things I haven't done, or even seen, but this one intrigued me, and I thought it was worth sharing untried.  Has anyone ever tried this method?  We aren't really sweet potato people, but now I want to give growing them a try.

Hey,

yes, I have tried this and it works,
It is just vegetative reproduction,

So sweet potatoes are good reproducers, of numbers once they take to the soil, they stick to the soil like what some people call weeds.

The sweet potatoes, take a very long time to reach harvest 6-12 months.

It is well suited to the wild approach.

Regards,
Alex

This is the way you grow slips from sweet potatoes.

Here in Thailand our Family pick the small ones, cut them in half, let the cutting dry for a few days and then put them half buried into trays.
Each potato produces between 3-6 new 'slips'

Then you take all leaves of the slip except the top two, bury the whole slip and keep only the top two leaves sticking out of the ground.

This way guarantees the maximum harvest of big sweet potatoes.

Sweet potatoes have been adapted to shorter and cooler seasons but are originally a warm season plant, they should do well very for you in California. Keep in mind that there are lot and I do mean a lot of different types of sweet potato. The "potato" is actually a root rather than a tuber and can easily be induced into sprouting "slip" in a variety of ways. I do mine in damp sand as and in the picture below but the sand is mostly just to hold them in place as they sprout the slips and roots. They will do the same thing just partially submerged in water.

Just put some in water or wet sand in a warm window or even outside if it's warm enough and they should make the slips. When they get four inches or so you can just pull or clip them off and plant. They are extremely easy to transplant. About any slip or stem cutting will easily sprout roots and take off growing. They actually do better it they have few to any roots when first planted. Just a couple little bumps on the stem is better than a bunch of roots. No need at all to pot the slips and establish a root system before planting out, just keep new slips watered very well for the first few days. In my experience a single root can make many slips and will continue making more as you remove the first ones. Here, where a late spring might delay planting earlier slips can be cut into sections to make still more.  

I have heard that market sweet potatoes are sometimes treated with chemicals that prevent sprouting but have never seen that myself. If you try it an don't get slips that could be the reason, just try again with some form a different source.

I'll stress again there are a LOT of different kinds. Different colors, different flavors, different growth habit and even different in how fast and how easily they sprout slips. Many types will produce a great harvest it about 100 days and at about that mark is generally when I harvest mine.  Some types don't make any large potatoes (storage roots) at all, no matter how long the season.