Winter can be a tough time for houseplants, as they are not getting the same amount of light and warmth that they would if they were outside. But just because the weather is getting colder, it doesn’t mean that you should neglect your green friends. To keep your houseplants healthy and happy during the winter, you need to give them a little extra TLC, including a powerful fertilizer. Here are a few ways to make your own fertilizer for houseplants in the winter, so you can keep your plants thriving even when the temperature drops.