How to Grow Milkweed for Monarchs: How Your Garden Can Help

Growing milkweed from seed is easy, but a few tips can help you get the most out of each package of seed. 

• Milkweed is slow to germinate, so cold-stratifying the seeds will significantly improve success. Simply sprinkle seeds onto a moist paper towel, fold the towel, and insert it into a plastic bag. Place the bag in a refrigerator for 2-4 weeks.

• Sow seeds indoors in a warm and bright location. Milkweed seeds need light to germinate, so barely cover the seeds with no more than ¼” soil.

• Keep your seeds moist until they sprout, but do not overwater. 

• When all danger of frost is past, harden off your milkweed seedlings and transplant them outside.

• Full sun is important for growing milkweed plants. Make sure they get direct light for at least 6 hours a day.

• A group of milkweed plants is more visible to migrating butterflies. Plan for at least 6 milkweed plants in a group, spaced 18 to 24 inches apart.

• Milkweed plants have a long taproot. Young seedlings will need regular watering. Established milkweed plants only need watering in drought conditions. 

• Common milkweed (Asclepias syriaca) can spread, so it is best planted in areas where it won't overtake other plants.

• Swamp milkweed (Asclepias incarnata) and butterfly weed (Asclepias tuberosa) are two milkweed species that integrate well in perennial flower beds.

• To keep milkweed from self-seeding, pick seed pods before they are fully developed. Or leave them to grow and drop seeds if you want your milkweed plants to keep spreading.

Monarch butterfly populations are in trouble. They’ve been declining for years because milkweed plants and wildflowers have been eradicated as land management practices have changed. Areas that used to be wild and teeming with milkweed plants are now becoming urban and suburban developments or are being cleared for agricultural use. Widespread use of pesticides and herbicides also threatens these vibrant orange butterflies.

Milkweed is essential to the monarch because this plant is the butterfly’s nursery. They only lay their eggs on milkweed, and in turn, milkweed protects the butterfly throughout its life cycle.

Milkweed leaves are the only source of food for a newly emerged monarch caterpillar. These leaves contain substances called cardenolides that are poisonous to birds and other vertebrates. (That includes humans and pets, so never eat milkweed, and wash the sticky sap off of your hands immediately.)

As the monarch caterpillars eat the leaves, this toxin helps to protect the caterpillar and butterfly from predators.

There are many varieties of milkweed. You may wonder if the variety of milkweed you grow matters. To work in harmony with nature, you want to choose milkweed that is native to your area. A milkweed variety that is appropriate for your area will naturally grow well and also help the monarch to migrate properly. The butterflies use the plants as landmarks or clues about where they should be during different times of the year.

Monarchs need more than milkweed to survive. Unlike the caterpillar, adult monarch butterflies get their nutrition from a variety of plant nectars. Just as milkweed plants are in decline, so are wildflowers and other nectar-producing plants. The good news is that you can be part of the solution to the reduction in monarch populations by planting milkweed and lots of flowers for these beautiful butterflies.

A pollinator-friendly garden is a great start, or maybe a wildflower garden. Monarchs and other pollinators love zinnias, cosmos, lantana, butterfly bush, and many other beautiful and colorful flowers that will make your yard lovely.

It's so easy to grow milkweed from seed and help the monarch butterflies! Encourage your friends to plant gardens with lots of flowers, including milkweed! The more butterfly habitat, the better for all of us.

Milkweed for Monarchs - NWF.org

Milkweeds and Monarchs 101 - PBS.org

Create a Habitat for Monarchs - MonarchJointVenture.org

Written by Teresa Chandler