The phone rang, and a gardener in tearful hysteria was there pleading for me to take her monarch caterpillars as she was totally out of milkweed leaves. At the time we had quite a few plants representing several species, both native and imports. I was shocked however when she brought me a box with 100 plus caterpillars. I went out to the garden and started dispersing caterpillars, one for a small plant two or three for larger plants. Deep down I knew full well we would soon be in trouble. In other words, I would run out of milkweed leaves too.
In the midst of that butterfly dilemma, I remember thinking what we need are larger milkweeds. As winter rolled toward spring, I started trying to buy more native milkweeds. Over 20 species are native to Georgia but finding them for sale can be a daunting task. I did find a wholesale nursery in south Florida selling a plant they called the giant milkweed or crown flower, Calotropis gigantea.
We've been growing it now for three years in Savannah, and I am pleasantly surprised. This year our giant milkweeds are 4 to 5 feet tall with leaves as large as those you would find on a rubber tree. That provides a lot of food opportunity for monarch caterpillars, and their cousins the queen and soldier which for some reason always go unmentioned in the butterfly world. They too must have milkweeds to exist.
The giant milkweed is native to India, Malaysia, Indonesia and China. Like me your first thought is, would our native butterflies lay eggs on them and then would the caterpillars feed on such a large import. The answer is yes. Would the monarchs and queens rather have a native milkweed species? You would think so, and for that reason, we have those too. I have hundreds of plugs of native species coming over the next few months.
But I wonder if a plant, maybe just one, of this enormous five-foot tall five-foot wide giant milkweed with silver foliage and incredibly showy blue and lavender flowers might just have a place in the garden. You see the monarchs and queen butterflies will use this import as a host plant too. There is enough leaf space to feed all who want to partake. I doubt you will ever tearfully report I ran out of milkweed leaves.
This plant is cold hardy in zones 11-12 and its native region can grow 8 feet wide and 15 feet tall. In Savannah, we have had them return slowly from the previous two winters, but we are always hedging our bets so to speak and rooting cuttings too. This means that more than likely you will be growing yours as an annual. If so you can easily root cuttings, holding them over for spring or grow in a movable container that you protect from freezing weather.
At the Coastal Georgia Botanical Gardens, we are using the giant milkweed in our pollinator beds with a host of other nectar and larval plants. We dress it up with a little tropical foliage. Butterflies and hummingbirds are always around. Though we are a little wind whipped after Hurricane Irma the butterflies are already showing they too weathered the storm.
Finding native milkweed plants for sale is still like finding a buried treasure. I assure you we are all working on it, not just in Georgia but your state, too. As we do, the Coastal Georgia Botanical Gardens will be evaluating the giant milkweed, for landscape performance and food for the monarchs, too.
(Norman Winter is director of the Coastal Georgia Botanical Gardens at the Historic Bamboo Farm, University of Georgia Cooperative Extension, and author of "Tough-as-Nails Flowers for the South" and "Captivating Combinations: Color and Style in the Garden." Follow him at: @CGBGgardenguru.)
(c)2017 Norman Winter
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