The sweet potatoes are in! We arrived on an unusually cloudy and cool morning for late May to find Takashi-san setting out the slips on the rows. Spaced about two feet or 60 centimeters apart, these little slips (bundle pictured above) will grow into some impressively massive tubers by fall (see photo for below for a sample of last years harvest) that will be made into everything from tempura to frilly desserts to mochi. (As well as my favorite sweet potato stew recipe!) Autum is also when carts selling roasted sweet potatoes appear. Hot coals carefully tended in the back roast the potatoes, which are simply sold whole as a warm tasty snack for those slightly chilly days marking the turn of the season.
The slips at first glance appear only to be stems with leaves at one end. A closer examination shows small nodules along its length where roots will form. These will turn into sweet potatoes, of course, but as the plant grows and stretches into the field more of these nodules will also anchor the plant to the soil. The plants require little to grow except a somewhat sandy medium, plenty of sunlight, and regular watering as they mature. No additional compost is needed to get a good hearty crop, which makes it easy to understand the historic popularity of growing this tuber.
Laid parallel to the hilled rows Takashi-san prepared earlier in the week, the slip is pushed gently down into the soil in a bow shape. This ensures that the nodules are spread somewhat evenly along the row, but not too deeply that their growth will be inhibited. The leaves, of course, remain above ground happily awaiting sunshine and water. Come autumn the entire field will be overrun with green leafy vines that nourish those tasty tubers and self-mulch the area, as well. (I'm drooling already at the thought.)