Milkweed is vital for the monarch’s life cycle. It’s the only plant monarch caterpillars eat. These caterpillars hatch from eggs laid on the plant before consuming its leaves.
However, not just any kind of milkweed will do. The key is this: You must plant milkweed native to your area.
The reason? Planting non-native types of milkweed risks monarch butterfly health. In many areas, non-native, tropical milkweed survives through the winter, allowing ophryocystis elektroscirrha (OE), a parasite that can be found on monarchs and milkweed, to build up to dangerous levels. On the other hand, with native milkweed, the parasite dies with the plant in the winter, ensuring that new milkweed grows with less risk from the parasite when monarch butterflies return in the spring.
You can locate vendors near you to purchase milkweed. Remember, local vendors do not always equal local seeds -- ask about the origin of milkweed seeds and plants before you purchase them. Another option, if you have milkweed in your area, is to harvest the plant yourself. Pro tip: To harvest seeds at the right time, make sure their pods pop open under light pressure. These guides can help you identify milkweed native to your area:
When should you plant milkweed? Ideally, the best time to plant milkweed seeds is in the fall so the cold temperatures and moisture that come with winter stimulate germination. You can also plant milkweed in the springtime. However, milkweed seeds planted in the spring need to first be put in soil or moist paper towels and placed in the fridge to simulate the effects of winter. This process is called artificial stratification.
If you are starting your seeds indoors, you should begin growing the plant 4 to 8 weeks before moving them outside. No matter how long winters last in your region, just make sure to wait until after the last frost before transitioning the plants outdoors. If you are using potted milkweeds, plant them after the last frost so that they do not die before the monarch’s mating season.
You should also know where and how to plant milkweed. Best growing practices suggest milkweeds be planted in the sunniest parts of your yard or garden. If you have a choice of soil, most milkweed species thrive in light, well-drained soils with seeds planted a quarter-inch deep. Make sure you check your seed packets or ask your local nursery for special instructions on the type of milkweed you are planting as there are some exceptions. Since milkweed is a perennial plant, you won’t need to replant it every year. You can harvest the seeds from your new plants and grow them in other parts of your yard or garden if you desire.
One final point: If you live north of Santa Barbara within 5 miles from the California coast, do not plant milkweed. Instead, plant nectar-rich flowers that match these areas’ natural vegetation and the monarch’s migration habits.
2. Grow Nectar-Rich Flowers