Understand butterflies' physiology and needs. Butterflies begin as eggs, then emerge as caterpillars before eventually transforming into butterflies. It's important that your butterfly garden provides food for caterpillars as well as fully developed butterflies. Caterpillars eat herbs such as parsley, fennel and dill; flowers such as violets, snapdragons and asters; and other plants, including nettles, milkweed and native grasses. Butterflies ingest food through a long, coiled tube, so they need to feed from plants with plentiful nectar. They are nearsighted and attracted to flowers growing in clumps rather than alone. Butterflies have a strong sense of smell and are often attracted to flowers with a powerful aroma.
Choose your plants. As with any garden, consider size, shape and color when planning how to group your plants, planting taller flowers in the back and grouping colors that are compatible. Also consider bloom time and plant accordingly so you'll always have something in bloom to attract the butterflies. Butterflies like sunshine for at least six hours a day and so do the plants they feed on, so consider how much space you have that gets enough sunshine. Specific plants that attract butterflies include annuals such as sunflowers, impatiens, marigolds, phlox and verbena; wildflowers like bergamots, black-eyed Susan, and blazing stars; perennials such as purple coneflowers, sedum, daisies and bee balm; and bushes, including blueberries, butterfly bush, lilac and sumacs. Purchase your plants at your local nursery, where the workers can help you with any questions you might have. Always choose plants with healthy-looking, green stems and leaves.
Prepare to plant. Dig the area where you intend to plant with a garden shovel or spade. Add organic matter to your soil, such as compost or peat moss, and work it in well. Carefully remove the plant from its container. Dig a hole the depth of the plant's root and place it in the hole, then gently fill in with the dirt you dug. Follow the directions on the package for how much space to leave between plants.
Maintain your butterfly garden. Water deep in order to help your plants develop strong root systems. Fertilize as needed with organic or commercial fertilizer, but avoid using pesticides or herbicides because these can kill beneficial insects, including butterflies. Try picking pests off by hand as soon as they show up so they don't get a chance to breed. Weed and mulch, and you won't need to worry about using commercial weed killers.
Add features to make your garden even more butterfly-friendly. Butterflies, like bathing beauties, enjoy sunning themselves, so provide flat rocks or stepping stones and place them in a sunny spot. They also like rotten fruit. Put a plate with rotting watermelon, bananas, pears or other fruit out for them. Provide water in bird baths or in small depressions in the yard. And don't be too fussy about cleaning up your autumn garden, because butterflies lay their eggs on the leaves and stems of plants. If you toss them out, you might be getting rid of what could be next year's butterflies.