(Best months for growing Yam/Oka in USA - Zone 5a regions)
P = Plant tubers
Yams needs a long growing time to produce the tubers.
Protect from early Autumn (Fall) frosts to give time for tubers to fully develop.
Planting needs are similar to potatoes. Yams can handle more shade than potatoes. Earthing up will help increase production.
The leaves look rather like clover. Dig up after the plant dies down and leave outside for a few days to dry.
Scrub and boil or roast with other vegetables.
We cannot help if you are overrun by giant slugs.