If you have a sunny backyard and are thinking of a creative way to utilize the space, may I suggest a butterfly house?
I once visited a butterfly house in Israel that was several thousand square feet in size and consisted of a simple wood frame covered with mosquito netting. I am sure you could make a butterfly house frame out of PVC pipe as well, whether it was a square frame or arched.
To make your butterfly house into a preferred summer residence for lepidopteran creatures, make sure there is exposure to a sizable portion of the day’s sun (8-10 hours a day) and that a steady water source (such as a birdbath or circulating fountain) is provided. Lastly, a butterfly house must not be located in the pathway of strong winds.
Keep in mind that from late fall to early spring butterflies hibernate or overwinter, and they will not be visible during this time. During spring and summer, keeping the entry to your butterfly house open will attract the visitors you seek. You can also order butterfly eggs and larvae online to supplement your butterfly collection.
Based on my experience, the best plants for attracting butterflies are, fittingly enough, butterfly bushes (Buddleia spp.). I once acquired a butterfly bush whose deep violet flowers had yet to bloom. The very first day a flower appeared, a black swallowtail butterfly materialized as if by magic. I could not remember the last time I had seen a swallowtail in my neighborhood, and I was astonished at how the presence of a single flower could make a seldom encountered lepidopteran feel at home in my backyard.
Everyone should grow a butterfly bush or summer lilac (Buddleia davidii) at least once. Seeing it in bloom is an unparalleled horticultural experience. Imagine thick inflorescences up to a foot long, each consisting of several hundred tiny trumpet flowers. Put your nose up close and the fragrance is that of lightly scented soap, similar to that found in the flowers of California lilac (Ceanothus spp.), another butterfly-attracting woody perennial.
The growth habit of the butterfly bush is as uncanny as its flowers. It can shoot up more than ten feet in a single season and should be cut back hard just prior to spring in order to make room for its phenomenal annual growth. Left unpruned, the butterfly bush will soon become top-heavy with floppy shoots and few flowers.
One notable quality of this butterfly bush species is its resilience to cold. Grow it in the Antelope Valley or the Tehachapis. A bonus in cold climates is not having to worry about pruning since nature will do this job for you. During a cold snap, the butterfly bush will die back nearly to its roots but regrow with great vigor when spring arrives.
On the corner of Tyrone Avenue and Hortense Street in Sherman Oaks, you may be overwhelmed by the presence of a 15-foot tall (and wide) butterfly bush covered with hundreds of fragrant lilac flower wands. It is true that the butterfly bush, especially during its first year or two in the ground, is a bit water needy but, once established, should never require water more than once a month to maintain. Still, they will flower more substantially when given a weekly soak. Although butterfly bushes prefer full sun, they can handle some shade and, yes, they attract every type of butterfly, from tiger swallowtails to silver-spotted skippers.
There are several species of Buddleia available. Flowers are mostly in the pink to lavender to dark purple and maroon range, but yellow, orange, and white varieties are also encountered, as well as varieties with variegated foliage. There is even a dwarf type that grows only 18-inches tall. You can prune butterfly bushes without mercy or just let them grow. As to their form, Budddleia davidii is fountain-shaped while Buddleia alternifolia will remind you of a flowering weeping willow.
Butterfly bushes have a wide natural distribution and there is even a California native butterfly bush (Buddleia utahensis), with small creamy yellow flowers, that grows in association with Joshua trees. Other California natives that attract butterflies include mahonia, manzanita, coffeeberry, wild buckwheat, toyon, California fuchsia, penstemon, fuchsia flowering gooseberry and, of course, our native milkweeds. Common ornamentals and bedding plants recommended as butterfly attractants include lantana, hebe, spiraea, gloriosa daisy, coreopsis, cosmos, scabiosa, marigold, delphinium, blanket flower, wallflower, lobelia, and sweet alyssum. Star clusters (Pentas lanceolata), which may be found in red, pink, white, lavender, or purple, are especially esteemed among flowering perennials in whose direction butterflies flutter. Salvias and star clusters may be propagated from four to six-inch shoot terminal cuttings.
Three butterfly-attracting ground covers are worthy of note: trailing yellow lantana, Mexican evening primrose (Oenothera berlandieri) and nasturtium.
Trailing lantana is a woody perennial that needs only to be cut back each spring to provide months and months of flowers.Mexican evening primrose fizzles in extreme heat or cold, but possesses redoubtable underground runners from which the plant regenerates itself in late spring as temperatures warm. Nasturtium will cover the ground with flowers that are yellow or orange or red, but all colors are edible. Several herb plants attract butterflies, including rosemary, oregano, bee balm (Monarda), and lavender.
All plants mentioned thus far produce flowers rich in nectar, which is the mainstay of the adult butterfly diet. However, in order to make a butterfly garden a year-round affair, you need to bring in plants that serve as a source of food for butterfly larvae (caterpillars) — plants that may or may not be distinguished for their nectar. The wisdom of planting milkweed (Asclepias spp.) is that it serves as both a source of nectar for adult monarchs and as food source for monarch larvae.
If you want black swallowtails to lay eggs in your garden, you will plant common fennel (Foeniculum vulgare). Fennel is a relative of parsley, cilantro, carrot, and dill, with soft and lacy foliage to match; all of these plants are appetizing to butterfly larvae. Fennel has a licorice fragrance when crushed and, although it develops as a biennial (blooming, setting seeds and dying in its second year), it self-sows reliably upon its demise. Other ornamentals that provide sustenance for caterpillars include mallow, monkeyflower, penstemon, passion vine and sunflower, as well as cherry, plum, birch, oak and willow trees.