Before beginning a butterfly garden project, it helps to understand what makes butterflies tick at different life cycle stages. The cycle begins when adult butterflies lay eggs on a "host" plant. Some butterflies will only lay their eggs on a single type of plant (e.g, monarchs and milkweed), while others have several choices. In about five to ten days, the egg hatches and the tiny caterpillar eats the host plant, shedding its skin four to six times as it grows. After two to four weeks, the full grown larva or caterpillar attaches itself to a twig or other object and transforms into a pupa. The body changes during this inactive stage and ten to fifteen days later the adult butterfly emerges. This process, called metamorphosis, means "change of form."
Adult butterflies feed on nectar from flowers (and in doing so, inadvertently pollinate some) while the larvae feed mostly on the foliage of plants. Ideally, a butterfly garden should contain or be located near a range of plants that will feed the butterfly at both stages.
You need only a small bed in front of your school or in the community to create an inviting oasis for butterflies. Consider using winter months to read, research, and learn about butterflies and the plants that will attract them in your area. Students may want to use information from books and seed catalogs to map out a butterfly garden. You can use sunny windows, GrowLabs, or other classroom light gardens to begin growing many types of butterfly garden plants indoors during the winter.
Both butterflies and plants like sun so plan your garden with a southern exposure or in a site that gets at least six hours of sun each day. A site sheltered from the wind by trees, shrubs, or a building, will prevent tall plants from blowing over, and allow your butterflies to feed, mate, and lay eggs in relative tranquility.
Nectar flowers provide a source of food for adult butterflies. Butterflies are attracted to brightly colored, sweet-smelling flowers that allow them easy access. (Composite daisy-like flowers are favorites.) Some of the preferred, easy-to-grow nectar plants are: butterfly weed, lantana, butterfly bush, black-eyed Susan, purple coneflower, lavender, cosmos, zinnia, and marigold. Butterflies are attracted to masses of color and fragrance, so try to plant groups of flowers instead of single plants.
Host plants upon which butterfly larvae dine are often "weeds," wildflowers, shrubs, and trees native to the area. Some species will lay eggs on only one type of host plant, while others have a range. Some of the primary plants for butterfly larvae include: aspen, alfalfa, clover, nettle, pearly everlasting, milkweed, grasses, hackberry, parsley, vetch, and willow. Although the caterpillars of some butterflies, like the cabbage white, are considered vegetable garden pests, you should never use pesticides-even biological ones-in a butterfly garden or you'll destroy your intended guests.
Puddles or other shallow water sources are important, primarily for male butterflies, more as a source of salt and amino acids than as a water source. If you have no naturally occurring puddles, try sinking a shallow container filled with moist sand, dirt, and/or stones into the ground. Keep it moist and watch for large congregations of male butterflies and their drinking buddies.
Dark stones in your garden can provide a warm spot where adult butterflies can bask in the sun and warm their bodies for flying.