How to Grow
Milkweed
Many milkweed species are identified by their tall stalks supporting broad leaves. Large clusters of small pink, orange, purple, or white flowers are very fragrant. When its stems or leaves are broken, a sticky white sap appears—the inspiration for its name.
Recommended Milkweed Varieties
- Swamp milkweed (Asclepias incarnata) - Common milkweed (Asclepias syriaca) - Whorled milkweed (Asclepias verticillata) - Showy milkweed (Asclepias speciosa)
If you have a sunny spot in your garden, you might consider planting milkweed seeds to support the monarch butterfly. Both the seeds and the plants can go into the ground in the spring or fall. If planting in fall, give milkweed enough time to become established before winter.
Until roots are well established, milkweed plants should receive a light daily watering, ideally in the morning. Once established, milkweed doesn’t need watering, except during periods of drought or in extremely arid regions.
Fertilizing Milkweed
Milkweed doesn’t need fertilizing. As a native plant, it tolerates poor soils. In fact, according to University of Michigan researchers, fertilizing tropical milkweed (especially with nitrogen) increases the levels of toxic cardenolides, which can stunt or kill monarch caterpillars.
Milkweed does not need to be pruned. However, where it grows as an annual, you might want to cut it back to the ground in the fall and spread the seeds for spring growth.
Milkweed can be grown from seed or cuttings taken from the root, rhizome, or stem. Cuttings should be taken in late fall or early spring when the plant is dormant.
Safety Considerations
Milkweed sap contains cardenolides that are toxic to people and pets. That makes it dangerous to ingest milkweed. Milkweed sap can also cause eye and skin irritation. Therefore, gloves, long sleeves, long pants, and eye protection are advised when working with milkweed.
Aphids, whiteflies, scale, spider mites, thrips, leaf miners, and milkweed bugs, all of which are immune to the plant’s toxins, sometimes feed on the leaves and seed pods.
Harvesting Milkweed Seeds
They don’t need to be pulled off the plant to assess their ripeness; simply apply light pressure. If they split at the seam, they’re ripe.