Interrupt the long winter nights with a brief period of light.
Explanation:
there are some plants that would naturally flower in the winter when there are longer nights. These plants are normally categorized under short-day (long-night) plants. On the other hand, there are other plants categorized as long-day (short-night) plants. These type of plants include lettuce, spinach and several others. They would flower in the late spring when dark periods are usually shorter. When such plants that do well in the early summer are planted during the long winter nights, it will flourish if there long nights are interrupted with a brief period of light. Thus the farmer has a greater chance of forcing the iris plant to bloom by interrupting the long winter nights with a brief period of light.
Wild animals always show preference for mates. Its part of the continous cycle of producing survivals and offspring. Even plants do it in their own way. Hope i was hhelpful?