Milkweed in Montana
Montana sits on the divide between eastern and western monarch populations, with showy milkweed along the Yellowstone and Missouri river systems and green comet milkweed on dry prairie. Riparian corridors matter enormously here, being the only reliably moist habitat for hundreds of miles.
The best milkweed to plant in Montana
Native to the state, garden-worthy and useful to monarchs. Start here if you are planting rather than identifying.
All milkweed species in Montana
| Species | Height | Flower | Bloom | Soil | Monarch |
|---|---|---|---|---|---|
| Swamp Milkweed Asclepias incarnata |
3 ft–5 ft | pink, rose, white | June to September | Wet / Average | |
| Showy Milkweed Asclepias speciosa |
2 ft–5 ft | pink, rose | May to August | Average / Dry | |
| Common Milkweed Asclepias syriaca |
3 ft–6 ft | pink, mauve, white | June to August | Dry / Average | |
| Whorled Milkweed Asclepias verticillata |
1 ft–2.5 ft | white, green | June to September | Dry / Average | |
| Oval-leaf Milkweed Asclepias ovalifolia |
8 in–1.7 ft | white, green | June to July | Dry / Average | |
| Green Comet Milkweed Asclepias viridiflora |
1 ft–3 ft | green | May to August | Dry | |
| Plains Milkweed Asclepias pumila |
4 in–1 ft | white, cream | June to September | Dry | |
| Slimleaf Milkweed Asclepias stenophylla |
1.5 ft–3.3 ft | cream, green | June to August | Dry |
Planting milkweed in Montana
Sow seed outdoors in September to November, before the ground freezes. Winter then supplies the cold-moist stratification most milkweed seed needs, and germination happens naturally as the soil warms. If you have missed that window, chill seed in the refrigerator for 30 days and sow after your last frost. The full method is here.
Montana spans USDA zones 3a–6a, so check the zone range on each species page before committing. Match the species to your site rather than the other way round: dry, sunny and poor suits butterfly weed and the whorled species; a damp spot suits swamp milkweed; shade suits very few milkweeds at all.
Plant at least ten stems in one group rather than scattering them, because female monarchs find dense patches far more readily. Add late-season nectar such as goldenrod and asters so the fall migratory generation has fuel as well as host plants. How to lay out a monarch garden.
Where to buy milkweed in Montana
Start with Montana Native Plant Society. State native plant societies run the plant sales worth going to: locally grown, untreated stock, at a few dollars a plant, sold by people who can tell you where to put it.
Elsewhere in the mountain west
Non-profit running a native plant nursery and demonstration gardens on the Colorado Front Range.
Independent Intermountain West native plant nursery.
Ships to you
One of the widest milkweed seed and bare-root ranges anywhere, with germination codes listed for every species.
Long-established independent nursery specializing in Midwestern natives.
Independent seed producer supplying restoration-scale native seed by the pound.
Family-run native seed producer for the eastern and central states.
Family-run Texas seed house focused on regional ecotypes.
These favor independent nurseries and non-profits over chain garden centers, which mostly stock unlabeled tropical milkweed and often cannot tell you whether it has been treated with neonicotinoids. Search the full directory by ZIP code.
Milkweed in Montana: common questions
What milkweed is native to Montana?
8 milkweed species are recorded in Montana, including Swamp Milkweed (Asclepias incarnata), Showy Milkweed (Asclepias speciosa), Common Milkweed (Asclepias syriaca), Whorled Milkweed (Asclepias verticillata). The full list is on this page.
What is the best milkweed to plant in Montana?
Swamp Milkweed, Showy Milkweed, Whorled Milkweed are the best combination of native, available and garden-worthy for Montana. Swamp Milkweed is the easiest to start with.
When should I plant milkweed seed in Montana?
Sow outdoors in September to November, before the ground freezes, so winter provides the cold stratification the seed needs. If you have missed that window, stratify seed in the refrigerator for 30 days and sow in spring after the last frost.
Does milkweed grow wild in Montana?
Yes. 8 species occur in Montana, typically on roadsides, field margins, prairie remnants and along watercourses. Montana sits on the divide between eastern and western monarch populations, with showy milkweed along the Yellowstone and Missouri river systems and green comet milkweed on dry prairie.
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Milkweed USA. (2026). Milkweed in Montana. Retrieved DATE, from https://milkweedusa.com/states/montana/
"Milkweed in Montana." Milkweed USA, 2026, https://milkweedusa.com/states/montana/. Accessed DATE.
Milkweed USA. "Milkweed in Montana." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/states/montana/.
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