It’s no secret that butterflies love milkweed. The long-blooming plant features tight flower clusters packed with nectar, and the leaves are filled with a milky substance that caterpillars adore. But more importantly, monarch butterflies cannot live without it. Adult monarchs seek the plant for its nectar and lay their eggs exclusively on the plant during the warmer months.
Now that fall monarch migration is in full swing, we’ve compiled a list of your top questions about monarchs and milkweed. Learn about pollinator plants, the fall monarch migration, how to tag butterflies, and plenty of other information about these winged beauties below.
Q: The most recognizable form of milkweed in Harris County is the tropical or Mexican milkweed, which features yellow or orange flowers. What other types of milkweed are good for pollinator gardens?
A: About 35 milkweed species are native to Texas, and about half a dozen grow in the Houston area. For monarchs, the healthiest varieties of milkweed include green milkweed (Asclepias viridis), zizotes milkweed (Asclepias oenotheroides), and aquatic milkweed (Asclepias perennis).
Q: I want to grow Texas native milkweed plants from seed. What is the easiest way to gather the seeds?
A: Milkweed seeds aren’t viable if you harvest them too soon. Wait until the milkweed pod starts to open before stripping the seeds from the pod. If you can’t harvest the seeds right away, place a net over the pod to prevent the seeds from blowing away. To strip the fluff from the seeds, place the seeds in a bag with a few coins and shake. The seeds should settle at the bottom of the bag.
Q: Can I plant different milkweed varieties together?
A. Because most milkweed varieties have different growing conditions, gardeners rarely plant them in the same location. For example, green milkweed, which grows in low spots along rural roadways, prefers heavy, occasionally muddy soil, and the zizotes milkweed requires well-drained soil. Aquatic milkweed, as the name implies, grows in wet bottomland areas along the edges of ponds and creeks. Green and zizotes milkweed prefer full sun, and aquatic milkweed tolerates some shade.
Q: I’ve heard something about a parasite called Ophryocystis elektroscirrha and that it infects tropical milkweed. Should I be concerned about this?
A: Ophryocystis elektroscirrha (or OE) is a parasite first discovered more than 20 years ago, but it’s only recently received attention. OE is concentrated in non-migratory monarch populations in the Houston area. The parasite persists in the Houston area because of our mild winters and long-blooming milkweed varieties, such as tropical milkweed (red and orange colored) and native aquatic milkweed. To prevent the parasite from spreading, cut back your tropical milkweed before each spring so that fresh growth will be available for the spring migration. (Most local monarchs raised in the summer and fall are non-migratory.)
Q: Should I remove my tropical milkweed?
A: Growing tropical milkweed is fine, especially in areas with frost. If it doesn’t freeze, be sure to cut back your milkweed before spring.
For more information, check out the resources below:
(Information provided by Mercer Greenhouse Manager Jacob Martin, TMS Grower Brandon Hubbard, and Mercer volunteer Don DuBois)
How to Grow Milkweed from Seed
Want to grow your own milkweed? Check out this step-by-step guide for growing milkweed in the Gulf Coast area, including zizotes milkweed (Asclepias oenotheroides), aquatic milkweed (Asclepias perennis), butterfly weed (Asclepias tuberosa), and green milkweed (Asclepias viridis).
- Rinse seeds with water.
- Fill a resealable bag half full of sand and add just enough water for the sand to hold its shape. The consistency should be like a sandcastle, not too wet or too dry. Make sure to label each bag with the name of the species and the date.
- Rinse the seeds and evenly spread them into the sand. Before sealing the bag, make sure to remove all air. Store the bag in your refrigerator.
- Cool the seeds for at least 30 days. Note: Refrigerating seeds is a technique used to simulate the real-world conditions a seed would receive outdoors as winter turns to spring.
- After at least 30 days, remove the seed bags from the refrigerator and start preparing your planting trays.
- Fill a seed starting tray with high quality seed-germinating soil like Jolly Gardener soil, which we use at Mercer. (A 72-count cell tray is recommended.)
- Dump your sand/seed mixture into a strainer and rinse with water until all the sand has been washed off. Only seeds should be left in the strainer.
- Plant four to five seeds per tray about ¼- to ½-inch deep and lightly cover with soil.
- Place the cell trays into a warm area or greenhouse. Water the seeds gently and evenly, using a watering wand or mister. Be careful not to displace the seeds with a hard stream of water. The professionals at Mercer use a misting table to water seedlings.
- Keep the cell trays evenly moist until germination occurs, which should take about four to seven days.
- After two to three weeks, the seedlings should be about 2 inches tall and ready to transplant.
- Transplant the seedlings into 4-inch pots filled with high quality potting soil. Plant one cell per 4-inch pot. If there are multiple plants sprouted in one cell, do not try to separate them. The roots are very fragile and will not take well if damaged.
After about one to two months, the seedlings will be ready to plant in the ground.