Readers of my blog may remember that about this time last year, I acquired one or two plants of every species of milkweed being offered at the NC Botanical Garden’s Fall Plant Sale. I thought it would be useful to write up an evaluation of how those plants performed in my garden during this year’s growing season. Recall that I divided my new acquisitions into two groups – those native to drier, well-drained habitats, and those preferring moist, even swampy conditions.

Boulder Garden Milkweeds

As I described in my original milkweed-related post, my boulder garden is a sunny, hot spot full of diabase boulders of varying sizes that are slowly eroding into smaller chunks, leaving a sandy, relatively thin soil surrounding them. Any plants that love heat and good drainage get a trial here, so this is where I planted

• Clasping Milkweed (Asclepias amplexicaulis)
• Whorled Milkweed (A. verticillata)
• Common Milkweed (A. syriaca)
• Poke Milkweed (A. exaltata)
• Butterfly Weed (A. tuberosa)

All of these plants are still alive and apparently healthy, but two of the species never bloomed.

Clasping Milkweed – This plant is still alive and green, but it never grew. At all. Usually, when a plant is unhappy, it eventually fades away, and the drought-plauged, hot summer certainly gave it plenty of excuses. But it persists, looking almost exactly as it did when first planted nearly a year ago. I know that some plants – usually woody ones – spend their first year after transplanting maximizing root growth while producing minimal top growth. But I’ve never seen this in a perennial. As long as it remains green, I will think positive thoughts about it. Perhaps next spring, new growth will appear.

Whorled Milkweed – This is the most un-milkweed-looking milkweed I’ve ever met. Its needle-like leaves give it a softer appearance than the other milkweeds. It never grew more than about 12 inches high, but it seems healthy.

About mid-July, it produced many tiny flower buds in the leaf axles. Eventually, these grew into the typical milkweed bud clusters I knew from other species.

In early August, they opened to produce waxy greenish-white flowers in a typical milkweed-looking inflorescence. The flowers were small, proportionate to the size of the plant, but they managed to draw a wide range of pollinators while they bloomed.

Despite all those pollinator visits, I have not seen a single seed pod on this species. But the plant itself still looks healthy, so I’m hoping it will survive the winter again, perhaps producing a more robust plant next year, since it will be starting from a larger size.

Common Milkweed – This was my other non-blooming milkweed in this bed. But unlike Clasping Milkweed, my Common Milkweed plant grew robustly, and still looks very vigorous. Interestingly, while the orange oleander aphids that notoriously plague milkweeds are all over my other milkweeds, they’ve barely bothered this one.

It grew to a height of about 2.5 feet, but has never shown any signs of flowering.

Poke Milkweed —This taller milkweed grew early and quickly in the spring. I was befuddled by its first blooming attempt in late May, which yielded one single flower. Not an inflorescence – just one pinkish-white flower.

My research confirmed that it should have produced a typical milkweed inflorescence. I decided to be grateful it managed at least one flower during its first year in my garden.

But then in early July, I noticed more flower buds! These produced typical milkweed inflorescences by mid-July.

As with my Whorled Milkweed, many pollinators visited, but no seed pods were produced.

Butterfly Weed – There is a reason that this milkweed species is sold often in plant nurseries. Its showy, bright orange flowers laugh at heat and drought.

One of my plants produced one round of blooms, but the other one is currently on its third round of blooms, and is simultaneously sporting a number of growing seed pods. Score!

It began blooming in early June, produced another round in July, and started up with a third blooming cycle in early September. Pollinators cannot get enough of this plant, and neither can I!

Water Feature Milkweeds

Three of the milkweed species I acquired last year are native to swampy habitats, so as I explained in my original post, I planted them in pots, which I inserted into my front water feature after danger of frost this spring. They were:

• Swamp Milkweed (Asclepias incarnata)
• Few-flowered Milkweed (A. lanceolata)
• Purple Savanna Milkweed (A. rubra var. laurifolia)

Two of these did beautifully, and one was a failure.

Swamp Milkweed – This is the other native milkweed you will find commonly in plant nurseries, because like its cousin, Butterfly Weed, it reliably produces beautiful clusters of blossoms that persist well in our summer heat while attracting myriad pollinators.

My two plants both grew to heights of about 3 feet, and produced two rounds of blossoms, first in early June, then again in late July. Now they are full of many expanding seed pods.

There’s a white-flowering form of this species, but I prefer the more common pink-blooming variety.

If you can provide an evenly moist garden bed, you can add this beauty to your garden. It doesn’t require as much water as I gave it. But in my yard, water almost always becomes a scarce commodity as summer progresses, so I stacked the deck in my favor by growing my Swamp Milkweeds in pots immersed in my water feature.

Few-flowered Milkweed – This is my only full-out failure. It stayed green and grew a bit through May, but then it began dying back, leaving nothing but a brown stem. Oh well, nothing ventured, as the saying goes.

Purple Savanna Milkweed – This native milkweed grew to about the same height as the Swamp Milkweeds. It also produced two rounds of blooms for me – one in early June, and again in early August. I would not characterize the flower color as purple.

To my eye, the flowers on my plant were more of a deep pink or mauve – very lovely – and very attractive to pollinators. This species did not set seed either, alas.

Where have all the Monarchs gone?

The only great disappointment I’ve had with my milkweed garden is the complete absence of Monarch butterflies. They’ve been reported nearby, and one even had the audacity to fly in front of me as I drove down my road about a mile from my house. But I have not seen a single Monarch in my garden and yard anywhere, and no caterpillars either. It was a rough year for butterflies in my area anyway, apparently due to an unusually cold and wet spell late last winter. I’m hoping that my milkweeds will return next spring even more vigorously, perhaps finally serving the visiting Monarchs for which they were planted. But even without the Monarchs I’d hoped for, I consider my milkweed garden to be a success. The pollinator diversity they attracted was exciting, and I’m hoping that the seed pods the Swamp Milkweeds and Butterfly Weeds are developing will yield new plants for my gardens.

But wait, there’s more!

You may recall that one of the flower varieties from Renee’s Garden I tried last year was an annual tropical milkweed variety called Butterfly Bright Wings. Last year, many of these plants produced seeds that floated everywhere. A number of those seeds produced plants that germinated in the boulder bed this year, where their mother plants had grown. It took them until last week – probably because of the drought – but these volunteers have finally begun to bloom. All appear to be the red form, which is the one I liked best anyway. I’m hoping they will again produce seed pods and perpetuate themselves next year.

Final Thoughts

For ornamental reliability, I recommend piedmont gardeners stick with Butterfly Weed and Swamp Milkweed. I have a feeling the other species that bloomed for me may be a bit more temperamental, and except for Purple Savanna Milkweed, they don’t produce very showy flowers.

I think perhaps the Greenhouse and Nursery Manager at the NC Botanical Garden may have reached the same conclusion, because he’s only offering Butterfly Weed and Swamp Milkweed at the upcoming Fall Plant Sale.

If you’re looking for vigorous, re-blooming flowering milkweeds that can handle our hot summers and might attract Monarch butterflies, you should stop by the sale and pick up some of these beauties. For the best selection, come on Members’ Night on Friday, October 2. Members can use their 10% discounts and get the best selection of plants. Plus there’s free food, beverages, and live music – and you can join at the door that night. I hope to see you there!