Time to Cut Back Tropical Milkweed

by | Dec 14, 2017 | Butterflies, Butterfly Gardening, Native plants, Perennials, wildflowers, Wildlife

Monarch butterflies. Photo credit: Pia-Riitta Klein.

We have grown to love monarch butterflies, with their striking orange and black markings and their fascinating annual migration from southern Canada 3,000 miles south to Mexico. To help them, we have increasingly planted milkweed, the only plant on which their caterpillars will feed. In northwest Florida, the milkweed species most planted has been tropical milkweed, Asclepias curassavica, as it is lush, showy and easy to grow.

Tropical milkweed, Asclepias curassavica, was visited by this monarch caterpillar who is now off to find a suitable place to make his transformation into a chrysalis. Photo by Mary Salinas, UF/IFAS Extension.

 

 

 

 

Tropical milkweed, unlike our native milkweeds that die back in late fall, will continue to grow through the winter unless killed by a hard freeze. Even if the cold kills the stems, it may regrow quickly from the roots. This seems like an advantage, but maybe not. The availability of a host plant for the caterpillars may be prompting adult females to stay and lay eggs rather than migrate south and be protected from deadly freezes.

Experts are also exploring links between the longer persistence of the tropical milkweed into winter and a build-up on those plants of a serious parasite Ophryocystis elektroscirrha, commonly referred to as OE.

So, what is the answer?

  1. Cut back any tropical milkweed to the ground at Thanksgiving. That may encourage female monarchs to migrate and prevent a deadly build-up of OE spores on the plants.
  2. Consider adding some native milkweed species to your butterfly garden. Here are some recommended species from Dr. Jaret Daniels:
  • Aquatic Milkweed (Asclepias perennis)
  • Swamp Milkweed (Asclepias incarnata)
  • Pinewoods Milkweed (Asclepias humistrata)
  • Redring Milkweed (Asclepias variegata)

    Swamp Milkweed, Asclepias incarnata. Photo credit: Chris Evans, University of Illinois.

 

For more information:

Are non-native milkweeds killing monarch butterflies?

Monarch Joint Venture: Potential risks of growing exotic (non-native) milkweeds for monarchs

Monarch Butterfly, Danaus plexippus Linnaeus (Lepidoptera: Nymphalidae: Danainae)

MonarchWatch.org

Gardening Solutions: Milkweed

 

 

 

Mary Salinas
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