HomeMy WebLinkAboutmilkweed growing instructionsHOW TO GROW MILKWEED
Purpose:
The reason for planting milkweeds is to help the declining population of the
monarch butterfly. Monarch caterpillars only eat milkweed, and there are several
varieties: common, butterfly, swamp, purple, and a few others. The City of Iowa
City has given away plugs of common milkweed, which has traditionally been
considered a weed in gardens and fields, but now many people are planting them
in their yards for monarchs. Monarchs lay their eggs on milkweeds in middle to
late summer and when the caterpillars hatch, they begin eating the leaves.
Milkweeds are necessary for monarchs to successfully reproduce.
Instructions:
The seeds for milkweed usually need to be cold stratified (kept moist in the refrigerator for several weeks)
to recreate conditions the seed would undergo during outdoor winter conditions. You can also plant them
in the late fall or winter to achieve this effect. If you are planting a milkweed seedling, usually the seeds
were then planted indoors to sprout, and then placed outdoors to grow and adjust to outdoor
temperatures.
When your seedling has two sets of leaves, plant it outdoors in a sunny location. Space plants about 1 ½ to
2 feet apart. Water the seedling after planting and make sure that it does not get too dry the first few
weeks after planting so it can get established. The plant will be relatively short during the initial year of
growth. In subsequent years, common milkweed will grow 2-4 feet tall and common milkweeds have
pinkish purple flowers which bloom from June to August (see above photo). Milkweeds have
root systems whose rhizomes will form colonies around the parent plants.
Care:
Milkweeds are a perennial plant, so will come up every year. It will grow a long taproot and
does not like to be moved after being planted. Be aware that sometimes small orange oleander
aphids may attack the plant (right). Don’t confuse these with monarch eggs. You should treat
the plant, being careful not to use chemicals that will harm monarchs. To manage aphids, see
more information online: http://monarchbutterflygarden.net/control-aphids-milkweed-plants/
Monarch Reproduction:
Monarchs arrive in Iowa around the end of May. They
will lay their eggs on the underside of the milkweed
leaves. The caterpillars start small, and then grow larger
like the one on the right. You may notice that monarch
caterpillars may eat almost all of the milkweed leaves,
but most of the time it doesn’t kill the plant. For more
information on milkweeds, monarchs, and our Iowa City
initiatives check out our website at:
www.icgov.org/ICMonarchs
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