Wikipedia defines “Winter Wheat” like this…
Winter wheat is a cereal. In the Northern Hemisphere, winter wheats are planted in the autumn, from September through December. Winter wheat sprouts before freezing occurs, then becomes dormant until the soil warms up in the spring. Persistent snow cover might be disadvantageous; however, winter wheat needs a few weeks of cold before being able to flower. The wheat grows and matures until ready to be harvested by early July.
This sounds all too familiar in several cases God has presented us with in our ministry. Not all, but some of the seed we sow seems to take hold, and then for some reason these folks wander off, despite our best efforts. Then, some time later, after they’ve endured the hardships of “winter”, they seem to long for that thing they experienced and it becomes ever more powerful to them.
Don’t give up too soon.