Cultivating a Butterfly Garden

ButterflyyellowtigerswallowtailAn interview with George Brinkmann
George Brinkmann is a consultant specializing in native landscape and habitat restoration. He’s the retired horticulturist from the Butterfly Pavilion in Westminster and a teacher and staff horticulturalist of the Denver Botanic Gardens. Colorado is home to 250 species of butterflies, more than anywhere else in North America. On any July day, if you hike on Mount Evans, you’ll see a variety of native butterflies.

FRL: How do you set about to plant a butterfly garden, and is that related to other insects as well?

Brinkmann: I think they are very interrelated. You need three elements. You need host plants that the butterflies feed on. You also need nectar sources and shelter.

To broaden that to a habitat garden, we are talking about other insects — pollinators like honeybees, ladybird beetles and different kinds of flies. Your aim is to get a mix of critters that balance themselves. They all need nectar sources.

Rabbitbrush is excellent, mint or thyme is a pollen or nectar source and easy to grow in this Rocky Mountain area. Incorporate these into your landscape and they’ll feed a number of insects. I have rabbitbrush at the Pavilion. It blooms in late summer and must have over a 100 honeybees on it.

FRL: How do you go about choosing plants?

Brinkmann: First, you need to plant native material. One thing you need to understand is the life cycle of the butterfly. The eggs are laid only on a host plant. The young caterpillars will only eat on a specific plant before they change into a chrysalis, the pupa stage, and then to a butterfly. Each species of butterfly has its own plant that they survive on.

For the Black Swallowtail, it’s dill or parsley. Many skippers (native prairie flies) feed on grasses on the prairie; the Variegated Fritillary is a native and feeds on flax, blue flax. The most common is the Painted Lady and it feeds on thistle. If you eliminate the plant, you eliminate that species. For example, if you don’t have milkweed, you won’t have monarchs. Grow milkweed, Asclepias tuberosa, called butterfly weed, or Asclepias incarnata. Both grow well in Colorado and are perennials. Incarnata grows where it’s wet. Grow chokecherry, the host plant for the Tiger Swallowtail, the largest butterfly in Colorado,

FRL: How would you go about designing such a garden?

Brinkmann: Besides natives, you can also use cultivars or hybrids in garden design. You need to have plants that grow in a specific environment. For example, if you have an area hot and dry then you need plants that thrive: cactus, prickly pear, penstemon, both native or hybrid.

Since you plant annuals in the spring, I’d pick the best for nectar source and zinnia is the best. I always say, ‘Plant them and they will come.’ So if you plant zinnias you’ll get butterflies and bees. Another annual is verbena; there’s a particular variety called ‘Homestead Purple’ that’s good. But there are many others, too. Some are annual, some are perennials. One exceptional verbena is bonariensis. It grows two to three-feet tall and reseeds itself. Another annual is the Mexican sunflower, Tithonia rotundifolia. All these are available in garden centers.

You’d be surprised at how much habitat for butterflies we’re losing every day. You don’t attract butterflies with bluegrass, junipers or crushed rocks and, yet, they are so extensively used.

FRL: Do butterflies also need water, or boggy areas?

Brinkmann: Yes, sometimes you’ll see butterflies clustered on the ground when you’re hiking. That’s called puddling. They’re getting salt and moisture from mud. They’ll suck the minerals from the ground, like calcium, which they need to sustain themselves.

Fireflies only exist in bog areas. We have natural bog areas all over Colorado. Roxborough State Park is one; Chatfield Arboretum is another. These are natural wetlands and we need to preserve these areas. In this metropolitan area of Denver there are a number of small bog areas.

FRL: How would you design a garden for spring, summer and fall?

Brinkmann: The spring bloomers would be viburnum, spireas, lilacs – the flowering shrubs. Then by summer some of the buddleias, the butterfly bush, will bloom although many of those are late summer. Then in the summer you have your annuals like zinnia and perennials. Then blue mist spirea, which is not a real spirea, is good for late summer. It also attracts bees. In the fall, sedum, such as dragon’s blood, draws insects–also milkweed and rudbeckia. It’s not the size of the garden that’s important, but the plant material. You don’t have to have a big garden, it could even be a flowerbox on your patio.

FRL: What about people who don’t want to attract wasps or bees?

Brinkmann: Some people don’t like wasps or bees, but without these pollinators, you would not have squash, cucumbers, tomatoes, apples, or any fruits. To have pollinators, you have to grow without insecticides. What I’ve discovered at the Butterfly Pavilion, with no toxic elements, is that nature has balanced itself. I have no injuries with insects. If you have insects on your plants that you don’t want, just prune it off or use water to hose the aphids off. Use the least toxic control that you can.

I’m 70 years old so I came from a whole different way of growing plants. I worked in a greenhouse and we used the most toxic ingredients known to man, derived from nerve gasses. We got tremendous effects for a while and then we got insects immune to that. Plus, from a medical standpoint it’s dangerous. I had a mask that leaked one time and I spent a night in the hospital. I’m so relieved to get away from that.

FRL: What are the best ways to provide shelter?

Brinkmann: To attract butterflies and birds, you need trees and shrubs like the serviceberry bush or a crabapple tree. You need a wind break like a big rock, because when a butterfly opens its wings it’s soaking up solar energy. Big slabs of rocks on the top of a berm give you pockets for the butterflies to hide in and you may have three generations over the summer.

For the butterflies who lay eggs in fall over winter, the chrysalis will be attached to the bottom of a rock. The Mourning Cloak butterfly winters as an adult, those are the first you’ll see in the spring in the canyons above Boulder. That’s a native butterfly. They can winter over in cold temperatures.

The message is to restore habitat and you can do that in a small way in your yard. Collectively, if everyone cooperated, that would be a big impact.