I live in Denmark. This year was my first attempt at growing ginger. I planted two small pieces with beginning shoots in soil along tomatoes in a greenhouse around may or june and let them grow until november. The plants grew quite tall, 1.5 meters in this time with nice long green leaves but no flowers. In november when it started getting cold, i dug them up and placed them in pots and brought them into the house which is very warm. The ginger stems in just a month turned yellow and withered away. Today i dug up the roots which grew surprisingly big and fat and juicy.
I'd like to continue growing ginger to get more of it. How do I go about it?
Sounds like the plant's growth cycle worked as it was supposed to do. Ginger leaves usually dry up after 8-10 months, so it's within the range - maybe a little shorter.
I'd just propagate using the same root cuttings technique you probably used for these initial plants. With any luck, this winter will be less brutal than last year's and you'll be able to get 1 extra month of growth in your greenhouse.
save some roots and plant again in the early spring, when the roots have "nubs" starting to form.. or buy more roots in the early spring from the grocery store when you can find some with nubs forming..