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Common milkweed
Asclepias syriaca

Swamp milkweed
Asclepias incarnata

Butterfly weed
Asclepias tuberosa

Growing milkweed

Goal: to establish several large stands of common milkweed and swamp milkweed and grow other milkweed species as appropriate and available.

Milkweeds seem to prefer disturbed sites and, as we've noted, they can appear for a few years and then vanish. We need to discover why this might be and what we can do (if anything) about this.

Existing and potential sites

Common milkweedButterfly Meadow
Field south of the Ash Woodlot (photo below)
South edge of New Woodlot near Prince of Wales Dr (potential site; photo below)
Field north of the Ash Woodlot (potential site; photo below)
Backyard Garden (in containers)
Swamp milkweedSouth edge of pond
Open area below dam
Backyard Garden
Butterfly Meadow
Poke milkweedAsh Woodlot (this species is unlikely to attract monarchs as it grows in semi-shade)
Whorled milkweedBackyard Garden
Butterfly Meadow (trial to see if monarchs are attracted to this species)

In the field south of the Ash Woods (not actually within our boundaries), milkweed has increased since about 2009 (photo above), but before that, was sporadic. Need to monitor this population - at least by taking photos every year.

This site near the red barn was thick with a large milkweed patch in 2006, but now has only the occasional one or two. In this case, trees have grown taller and are shading more of the site, DSV has moved in, and there may be other factors causing the decrease in milkweed plants.

Potential site for planting, this area just south of the New Woodlot and north of the barn gets plenty of sun and is still open. The soil contains a lot of clay, but common milkweed should do all right here.

In early fall 2011, we received a number of donated common milkweed plants - mainly from Ken Young and Iola Price. We cut the tops back to about half the length of the stems. By the time of planting, most of the leaves had dropped off, but we are hoping the plants will grow back from their roots. We also scattered a number of milkweed seeds in this area and in the northeast corner of the Old Field.

In May 2012, many of the donated plants were growing well, although completely surrounded by DSV (image below). The DSV was subsequently cut and we marked the milkweeds so as to monitor their growth. By early April, all had disappeared, probably because of lack of rain.

Cutting to promote new growth

Monarchs prefer to lay eggs on fresh new milkweed leaves, so that the caterpillars will have good nutritious food. However, by early August when the last cohort of caterpillars are growing, many milkweeds are becoming yellow and dying back.

We thought that we could encourage new growth by cutting back some mature plants right after they had finished blooming. On 10 and 12 July 2012, we experimented by cutting some stems about halfway down, expecting side shoots to develop. However, these plants stopped growing completely.

Meanwhile, plants along our farm road, which had been mowed on 13 July, regrew from the remaining roots or lowest leaf axils and were about a foot high by early August. On Aug. 2, Christine and Claudia found 5 eggs and a first instar catrpillar on these plants. At least 3 monarch butterflies (possibly 5) were flying around the same area.

Milkweeds transplanted on 3 June had produced many side shoots by 7 July, but plants cut back in early July did not have any side shoots. Timing? Weather conditions?

Propagating milkweeds

Goal: To determine best practices for moving plants and for growing them from seed.

In 2011, we scattered a number of seeds in the field north of the Ash Woods among the stems we planted and also in the northeast corner of the Old Field. Need to monitor these areas to see if we can tell whether any of the seeds grew.

Need to check the stems to see how many survive. Find out more about moving plants. Try propagating by cuttings.

Germination rates

SpeciesSeed source and growing conditionsGermination rate
Common milkweedcollected March 12, 2012 (Barryvale Road), sowed indoors along with other plants for annual plant sale12.5%
Swamp milkweedcollected March 12, 2012 (Barryvale Road); these were collected from a beaver dam, so had been under the snow in mud all winter; sowed indoors along with other plants for annual plant sale67.5%
Common milkweedcollected in March, sowed outside in a tray of potting soil15%
Common milkweedcollected in October (Duck Club), kept in paper bag in unheated garage over winter; sowed outside in trays of topsoil and in garden in late May (200 seeds each)
Buried seeds started earlier, but produced fewer seedlings; seeds sown in garden did not sprout at all
about 12%
Common milkweedcollected in October (Duck Club), as above; sowed outside in 2 trays of potting soil on 2 July (200 seeds each)
Common milkweedcollected in October (Duck Club), as above; sowed inside on damp vermiculite in 5 germination containers on 2 July (100 seeds each)
Common milkweedcollected March 12, 2012 (Barryvale Road); sowed outside in tray of potting soil on 2 July (100 seeds)

Articles on growing milkweeds

This page was revised 10 February 2013
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Photos by Christine Hanrahan
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