Those of you who have read my blog for a while may have noticed that when I fall in love with a native genus of plants, I tend to want to grow at least several different species in that genus, usually because I think the plants are beautiful, and because I like to see how many of these natives I can site well enough to flourish in my yard. Basically, I like to experiment. I’ve done this with southeastern US native deciduous Magnolia species, and with southeastern native deciduous azalea species. In both of these cases, the plants are beautiful and provide three or four seasons of visual interest.
Not so for my latest experiment. At this year’s plant sale at the NC Botanical Garden, I took advantage of their offerings of native milkweed species, because I’m eager to try to help the Monarch butterfly population. As I wrote here, Monarch butterfly populations appear to be declining precipitously, probably mostly due to habitat destruction, although other factors are also relevant. Monarchs only lay their eggs on species of native milkweeds. These plants contain toxins that Monarch caterpillars can process, but avian predators find the toxins make the caterpillars inedible, even when they metamorphose into winged adults.
A few of our native milkweeds produce flowers worthy of any garden. Butterfly Weed (Asclepias tuberosa) and Swamp Milkweed (A. incarnata) can be found in many plant nurseries. With proper siting, both will thrive in most Piedmont gardens. The flowers attract numerous pollinators, and in my yard, the Monarch butterflies usually show up in early autumn to lay eggs on the plants, usually after the flowers have morphed into the long seed pods characteristic of the genus. The caterpillars usually strip almost every leaf off the plants, then turn into emerald chrysalises attached to nearby vegetation.
As a gardener, I routinely assess plants not only for their visual impact in my landscape, but also for their growing requirements. In the case of native milkweeds, I soon realized that they fall roughly into two groups, based on growing conditions. Butterfly Weed represents one group — the milkweeds that require excellent drainage and lots of sun. Swamp Milkweed represents the moisture-loving milkweeds. Some of these can tolerate a bit more shade, but not much; all of them need a constant supply of moisture.
I have a wonderful sunny flower bed built around a stand of diabase boulders beside my driveway. The soil is sandy and full of rocks, bits of boulder slowly breaking down. Drainage is excellent, and I’ve had good success there with plants that need these conditions. This is where I planted my new native milkweeds that need good drainage and hot sun:
- Clasping Milkweed (Asclepias amplexicaulis)
- Whorled Milkweed (A. verticillata)
- Common Milkweed (A. syriaca)
- Poke Milkweed (A. exaltata)
- Butterfly Weed (A. tuberosa)
All of these milkweeds produce similar flower clusters, and they’re all pretty, mostly in an understated way. Some of them — Poke and Common Milkweeds — grow quite tall, and likely will look a bit unkempt as they mature, which is why I put them toward the back of my bed, where they won’t be particularly conspicuous. Poke Milkweed may need a bit more moisture, so I sited it on a downslope, where it should receive more water.
Even the less showy flowers will attract numerous pollinators, and I’m hoping Monarch caterpillars will appear to devour them next summer/fall. My newly planted good-drainage-loving milkweeds are not mulched. I put small rocks around their bases to help me remember where they are after these perennials die back later this fall. I planted two Butterfly Weeds toward the front of my boulder bed. They are smaller plants at maturity, and their showy, bright orange flowers will look lovely against the boulders.
You may notice a flowering plant amidst all the greenery in one of the pots in the above photo. That was my one impulse buy at the plant sale. I had gone there fully intending to buy only milkweeds, but this lovely native orchid caught my eye. I have always loved the Nodding Ladies’-tresses (Spiranthes cernua) that bloom in the NC Botanical Garden’s carnivorous plant display this time of year. So when I spotted this healthy specimen — actually two blooming plants in one pot — I had to have it.
I’ve had great success growing other wetland plants, including carnivorous pitcher plants, in pots that I then place inside my shallow water feature during the growing season. These plants overwinter in their pots inside my little greenhouse, where they sit in saucers of water that I refill as needed to maintain the constant moisture levels they require.
I decided to plant my newly acquired wetland-loving milkweeds in pots that I will treat like the ones currently still sitting in my water feature. Because I’ll be draining that little pond soon, I decided to simply put the new pots in water-filled saucers for now. Next spring after frosts are gone, they will go into the little pond with the other moisture-loving plant pots.
As with the showy Butterfly Weeds, I acquired two Swamp Milkweed plants. Their bright pink flowers will look great amidst the other water plants next growing season. The moisture-loving milkweeds in my new pots are:
- Swamp Milkweed (Asclepias incarnata)
- Few-flowered Milkweed (Red Milkweed) (A. lanceolata)
- Purple Savanna Milkweed (A. rubra var. laurifolia)
These, plus the Nodding Ladies’-tresses, left a bit of room in the pots, so I popped in a few Cardinal Flowers (Lobelia cardinalis) that I had in pots elsewhere. Cardinal Flowers can tolerate drier soils, but they planted themselves in my wetland pots some time ago, and the bloom stalks on those wetter plants are always the tallest in my yard.
I am hopeful that my milkweed experiment will add visual interest to my landscape, attract copious pollinators, and most of all, be utilized by hungry Monarch butterfly caterpillars. Nurturing Beauty in all her guises will always be the greatest reward for this gardener.