PLANT OF THE MONTH
October, 2009
Plant of the Month Feature
by Kathy Anderson
Arboretum Roots Board Member
Asclepias curassavica
'Silky Deep Red' Milkweed
Wanted: monarch butterflies! Must have: milkweed! Problem: most varieties of milkweed are rather scruffy-looking for the average city garden AND monarch butterflies ONLY lay their eggs on milkweed plants because that is the only plant eaten by their caterpillars. What to do? Try to encourage the growth of the Common Milkweed we see on Iowa roadsides even though it is very invasive, very tall, falls over by midsummer crushing our prized rose bush, and harbors some insects we would prefer not to invite into our gardens? Or plant one of the several other milkweed varieties most of us don’t know exist? There are others, commonly known as Butterfly Weed, Swamp Milkweed, Red Milkweed, etc., but they are sometimes hard to procure, often require support rings, and tend to lose their vigor about midsummer. You see, monarchs are like pandas - one plant critters. The female monarchs lay their eggs only on milkweed as their caterpillars EAT only milkweed so an interest in monarchs must include an interest in milkweed.
Ta-dah! Enter >Asclepias curassavica 'Silky Deep Red' or Scarlet Milkweed! It is an attractive plant in the home garden or yard, stays vigorous until a hard frost, is relatively pest free in our zone, and seems to thrive whether we have the rains of 2009 or the relatively dry seasons we often have in Iowa. As an added bonus bees like it, birds (hummingbirds, finches) like it and it makes an attractive cut flower which by cutting encourages branching on that stem. In addition to the red color a golden yellow, silky gold, is available and I plant both! Now that I’ve convinced you that you must have this plant, read on . . .
Lest you think this plant is all good news there is one slight drawback. It usually grows as an annual in Iowa and is perennial south of us in zones 7-10. However, it is easy to grow from seed and actually reseeds itself wherever seeds hit the soil. So get one plant - available at some nurseries - or find sources on the internet - and you’re set for life. We are going to start our own plants at the Arboretum in spring, 2010, and may be able to give some away. Check with us on that in May or early June.
This plant typically grows as a sub shrub 3-4 feet tall so give it space in the back of your garden or tuck it in between other plants. It thrives best in full sun to partial shade. I have read it can be started from cuttings but I can't confirm that though I am going to try it immediately. If one cuts some of the stems midway down branching will occur thickening the plant and encouraging more flowers, which grow on the ends of stems. These plants seem oblivious to rain storms and wind and stay standing erect from spring planting until frost - no staking needed! Also, the later monarchs, the August ones, seem to like to lay their eggs on these when other varieties of milkweed have petered out. I’ve often found eggs and very tiny caterpillars and, of course, the big ones, as late as the end of September.
There is practically NO reason NOT to include this plant in your yard as soon as you can! You can view specimens of both colors in the newer butterfly garden at the Arboretum amongst the annual zinnias and blue salvia. Hurry before frost lays them low!
About the author: Kathy Anderson is a retired Clinton Community Schools elementary teacher and has been an Arboretum volunteer, especially in the butterfly gardens, and the No Child Left Inside program for several years. She serves on the City of Clinton Tree Commission. She has lived and gardened in Minnesota, Iowa, Colorado, Delaware, and Texas, and has striven to be outdoors observing nature every minute possible her entire life. Many years ago, while teaching second grade at Whittier School, a student’s parent knocked on her classroom door holding a monarch butterfly chrysalis which was about to burst open. The parent was sure all in the room would like to watch the butterfly emerge from the chrysalis. Kathy and her students were hooked! She spent the rest of her teaching years watching, reading, and sharing with her students the miracle of monarch metamorphosis. Hence, the many varieties of milkweed growing in her Clinton garden and the interest in the growth and expansion of the butterfly gardens at the Arboretum.