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Milkweed guides

Everything practical: getting seed to germinate, when to sow, what is eating your plants, and how to build habitat that works.

Growing

Growing How to plant milkweed seedsMost milkweed species will not germinate until the seed has been through a cold, damp spell. Sow in fall and winter does it; sow in spring and you have to do it in the refrigerator first. Growing When to plant milkweedSow seed in fall so winter can stratify it. Put plants in the ground in late spring. Avoid midsummer, when heat and drought kill new roots before they establish. Growing Collecting and storing milkweed seedTime the harvest wrong by a week and the seed either is not ripe or is halfway across the county. Here is how to get it right, and how to de-floss a pod in thirty seconds. Growing Milkweed pests and problemsAlmost nothing you find on a milkweed needs killing. The bright orange aphids are the exception people ask about most, and even they rarely matter. Growing Buying milkweed seeds and plantsTwo questions decide whether milkweed is worth buying: is it native to your region, and has it been treated with systemic insecticide? Growing Growing milkweed in containersMilkweed in a pot is entirely possible if you respect one thing: these are deep-rooted plants, and depth matters more than width. Growing Milkweed cultivars, and whether monarchs mindA garden center sells you ‘Ice Ballet’ rather than Asclepias incarnata. Monarchs will generally still use it; what matters more is whether the plant is native to your region and where its seed came from.

Monarchs

Monarchs Milkweed and monarch butterfliesA monarch caterpillar can eat milkweed and nothing else. Remove milkweed from a landscape and you remove monarchs from it. Monarchs The tropical milkweed problemIt is the most widely sold milkweed in America and, south of the frost line, the most damaging plant a monarch gardener can buy. Monarchs Creating a monarch waystationA monarch garden needs three things: enough milkweed to raise caterpillars, late-season nectar to fuel the migration, and no pesticides.

Identification

Identification How to identify milkweedEvery milkweed shares the same five-part flower. Once you can recognise it you have the genus, and leaf shape, arrangement and habitat narrow it to the species. Identification Milkweed lookalikes and how to tell them apartMilky sap is not enough. Several unrelated plants bleed white, and two of the lookalikes actively kill monarch caterpillars. Identification How milkweed pollination worksMilkweed does not shed loose pollen. It packages it into saddlebags that clip onto an insect leg like a piece of luggage, and it does this so awkwardly that fewer than one flower in a hundred sets seed.

Safety

Safety Is milkweed poisonous?Milkweed is genuinely toxic, but the practical risk in a garden is low. The species that cause real harm are the narrow-leaved ones, and the usual route is contaminated hay.

Ecology

Ecology Everything else that lives on milkweedMonarchs are the best known of them, not the only one. Roughly a dozen insects in North America eat milkweed and almost nothing else, and most of them are the same orange and black. Ecology Milkweed around the worldMexico has more milkweed species than the United States and grows the forest the monarchs winter in. Canada had it on a noxious weed list until 2014. And in Europe, the plant Americans are urged to plant is one landowners are legally required to remove.