Butterfly Bush

What is a butterfly bush? Does it really attract butterflies? Buddleia does indeed attract many varieties of butterflies including Fritillaries, Western Tiger Swallowtails, Tortoiseshells and Red Admirals. Red varieties may attract hummingbirds!
The butterfly bush was brought to England in the 1700s. It's a native of China where it's called summer lilac. Buddleia comes in many varieties and blooms from midsummer through September. When in bloom, butterfly bushes are covered with blossoms in shades of white, red, pink, yellow, purple, blue and maroon They look much like lilac blooms and are honey scented.

Buddleia grows best in fertile, well-drained soil, however, it's very drought tolerant and will survive in some pretty tough situations. In fact, in some places it's considered invasive, so it's recommended that if you live in a natural, wilder area it's best to pull up any volunteers rather than let them spread. The bush can grow from 5 - 10 feet and it has a wide, arched branching. You'll need about 6 foot between bushes when spacing.
It's recommended that you cut back the bush each year in winter - in cold climates cut back around November. How close you cut it depends on where you are. If you have a lot of heavy snow it's better to trim back to around 3 foot or so and mulch. If your snow if light then even a foot is okay. It will grow back the next season, and it helps keep it under control. If you don't do this, then at least prune well each year and remove the old woody branches. In warm climates you may cut it back after blooming to encourage a second bloom. Deadheading the blooms can also extend the bloom time, so it's worth the effort.
The butterfly bush needs full sun but will grow in light shade if that is what's available. They are great grown on their own, or in the very back of a border. Of course they are perfect for a butterfly or hummingbird garden. New bushes can be grown from seed, though it's a challenge. Pre-chill the seeds for 4 weeks before sowing. They need light to germinate so just press them lightly onto the soil. They will take up to 90 days to germinate. Cutting or layering stems is an easier way to propagate.
A note if you've never grown butterfly bushes:
They look dead first thing in the spring and some branches die, but wait until May and June to see how it's done over the winter. If there are some dead branches, simply trim them off. In climates like Michigan and other Midwestern states it dies back, and growth only comes from the new wood, so you will have pruning to do in the spring.
Buddleias also make pretty cut flowers. Cut when half the flowers on the stem are open, but before they begin to fade. These should last about a week in a vase with a conditioner if you refresh the water now and then.
This article is taken from- http://www.gardenguides.com/625-butterfly-bush-garden-basics-flower-perennial.html