Cover them
Just like you cover yourself, covering plants is necessary in winters. The frost lying on the bed of soil in the plant can freeze the growth of the plant. The freezing plant can literally die because of the absence of oxygen and it is necessary to cover the plant with some cotton cloth.
Show them sunlight
Showing the sunlight, whenever it is available is necessary. Sunlight is important in the growth of the plant and if we speak in layman language, plants prepare food from the sunlight. Most of the time it happens that people cover their plants in the indoors because of the sunlight and just because of this, plant can miss the sunlight because of the indoor placement.
Proper planting
Proper planting is necessary in winters and you should always plant your bulb in the proper planters where ventilation is enough. You can buy planter from online nursery which is easily available on online portals.