Common milkweed – friend or foe?

Horticulture Hints

Do you remember decades ago when “walking beans” was a common way for area youth to earn pocket money, by removing milkweed and other weeds from soybean fields? Pulling, hoeing or corn knives were among the arsenal used. Next came the era of “riding the sprayer” involving sitting on seats pulled behind a tractor to chemically spray milkweed and other weeds growing in the field. With today’s innovations, these activities of the past are no longer the norm for removal of weedy plants considered noxious or undesirable to be growing in farm fields.

Although past generations were intent on removing milkweeds, today’s focus is on encouraging folks to let milkweeds grow in the landscape as to benefit bee and butterfly pollinators. Monarch butterflies use the milkweed to lay their eggs on and then the hatching caterpillars will feed on milkweed leaves. But beware, the common milkweed can be very invasive, as it is easily grown by seed and sends out rhizomes from the mother plant that sprout new growth. Thus, measures must be taken to avoid overpopulations in the home garden.

Mature milkweed plants have a deep growing tap root, which if broken off near the soil surface, can form several growing points from which new plants will emerge. Mature seed pods, once split open have hundreds of seed with silky hairs that are easily airborne. If left unchecked, seeds can spread by wind to undesired areas as well. Remove seed pods prior to maturing to prevent unwelcome dispersal.

Mature milkweed seed may be saved to share or for replanting. Harvest just as the seed heads are browned and before pods open completely. Replanting common milkweed seed is best done in the fall, with a light covering of soil.

Did you know? It is a good idea to wear gloves when pulling milkweeds from your garden. Milkweed plants contain a sticky, milky white latex-type substance. Some people, should they come in direct contact with the latex, may experience an allergic reaction. The compounds in milkweed latex are stored by Monarch butterflies in their tissue as a protection which makes them inedible or toxic to birds and other animals.

Questions? Contact McCormick at yvonne@iastate.edu for information or advice.

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