While it may be too early for most seeds to go outdoors in colder parts of the country, it's the perfect time to get started on indoor planting and windowsill gardens. Arugula, beets, carrots, English peas, lettuce, peppers, tomatoes—plant those seeds indoors now (use a UV lamp if your house doesn't get sufficient sunlight), and you'll have strong seedlings ready to drop into your garden when the time is right.