Tropical Asclepias

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Monarch caterpillars were crowd pleasers at Field Day this year

If you have a pollinator program, or you want to build a butterfly garden, you need to buy tropical Asclepias. For proof, we go no further than the Butterfly Bed we build for Field Day. Our garden tours bunched up when we passed it, and all the cameras whipped out. We had trouble pulling the crowd down to discuss the next garden.

A better butterfly magnet than the traditional tuberosa, Tropical Asclepias have a high fun factor. The artful blooms became a personal favorite of the office staff, and we were impressed how the buyers reacted to them. As a result, we are offering three cultivars next year. Let’s take a look at these unusual plants.

ASC Silky Gold
Asclepias ‘Silky Gold’ with delicate scaffolds under the origami-like flowers

The first two come from the Silky series, PanAmerican’s take on the classic look. Like all Asclepias, the flowerhead is built from a cluster of florets. In ‘Silky Gold’, they are bigger, loosely bunched, and supported by arches on the ends of the stems. It has the look of miniature paper origami. Those flowers are held at the tips of the stems, about waist-high, so they are very easy to inspect up-close.

ASC Silky Deep Red
‘Silky Deep Red’ has a complex mix of colors

’Silky Gold’ has a single color, but its sister cultivar, ’Silky Deep Red’, has an interesting reveal. Their hoods are bright red when the flower first opens. As it matures, those hoods open to reveal an orange interior and a bright yellow floret centered inside. The color lines are very sharp inside the origami shape.

ASC Monarch Promise
Variegated foliage of ‘Monarch Promise’ with pink tinges

'Monarch’s Promise' comes from Hort Couture, and it brings a rare trait to the game. The flowers look like ‘Silky Deep Red,’ but the lance-like leaves have white streaks—and the edges have pink tinges. This is tri-color variegation. The internet says it was found by the daughter of a butterfly grower in Florida. The leave was so beautiful, she stopped and showed it to her mom. 

Monarch Catapillar
Fat, two-horned monarch caterpillers were everywhere in the garden

Of course, the promise is caterpillars – lots and lots of them. With tropical asclepias, you get them in spades because they offer tender - not tough - leaves and flowers to eat. Like all milkweeds, these cultivars offer home, succor and protection to Monarchs. The adults lay eggs in the nooks. The flowers and leaves are food for the young. The sap has a toxin they keep to ward off predators. That bitter-tasting compound stays with them after they molt into butterflies. The full story has a ‘Life Circle’ aspect that makes them fascinating to kids. 

 MG 8289
We mixed in Tithonia 'Red Torch' and Rudbeckia 'Indian Summer'

Tropical Asclepias stand about waist high, tall and slender with olive-green lance-shaped leaves. Unlike the perennial tuberosa, the tropicals have no taproot. They winter kill in the Ohio River Valley, which is a good thing. It encourage Monarchs to move along to their final destination rather than lingering around. PanAmerican likes to point out that Florida landscapers love these plants for their ability to hold up in humid landscapes, so they handle our summers without a problem. We saw no performance problems at our place.

Classic milkweed seeds entertained our kids . . . these seeds don't survive the winter

They also mix well into summer containers. This means apartments, patios, decks and balconies can invite visitors to their pollinator party with butterfly combos and planters. If you want, you can keep them indoors over the winter with reduced water and a cool place. They are deciduous, so cut back the tops after frost. They are not winter houseplants.

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This garden got more photographs than all the other gardens

It’s best to plant Tropical Asclepias in full sun, in lighter and drier soils, but overall they are not too fussy. However, if you are serious about your butterfly support, they like slightly acidic soil (think pine needle mulch) and perhaps a phosphorus-rich fertilizer to boost the bloom count.

TIT Red Torch
The eye in Tithonia ‘Red Torch’ really complimented Asclepia 'Silky Gold'.

You do want to plant them in mass. They are not bulky, so bunch them up to make an impression. Also, two caterpillars can devour a plant within the two weeks between egg and chrysalis. Two doesn’t make a dent in the world of Monarchs, so plant more. After the ‘pillers leave bare stems behind, don’t feel bad. Tropical Asclepias are well-suited to their job. Ours bounced back with fresh leaves and new flowers within a couple of weeks.

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A good example of the tip-end presentation of Tropical Asclepias, mixed with ripening pods

To handle the bare spot that occurs during feeding season, mix in beefier companions like Tithonia ‘Red Torch’ and Rudbeckia ‘Indian Summer’ so the garden still feels full. Diversity is always good, the garden will look great even at the height of caterpillar season, and you will see more than just Monarch visiting the site, like Eastern Tiger Swallowtails, Painted Ladies, Humming Birds and Giant Swallowtails.

But if you want the king to stop by, you want the Tropical Asclepias.

Asclepias ‘Silky Deep Red’, Silky Gold’, and ‘Monarch Promise’ are available in the 4.5-inch pot; ‘Silky Gold’ comes in the 6-inch pot as well. Rudbeckia ‘Indian Summer’ and Tithonia ‘Red Torch’ also come in the 6-inch pot.

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