Milkweed for Monarchs
Monarch caterpillars feed exclusively on the leaves of milkweed, the only host plant for this iconic butterfly species. As such, milkweed is critical for the survival of monarchs. Without it, they cannot complete their life cycle and their populations decline.
Indeed, eradication of milkweed both in agricultural areas as well as in urban and suburban landscapes is one of the primary reasons that monarchs are in trouble today.
The good news is that planting milkweed is one of the easiest ways that each of us can make a difference for monarchs. There are several dozen species of this wildflower native to North America, so no matter where you live, there is at least one milkweed species naturally found in your area.
Planting local milkweed species is always best. You can collect your own seed or purchase seed or plants to add to your garden, or any landscape in your community. Three species have particularly wide ranges and are good choices in most regions: common milkweed (Asclepias syriaca), swamp milkweed (A. incarnata), and butterflyweed (A. tuberosa). The latter two are highly ornamental and widely available via the nursery trade.
Growing Instructions for Milkweed
Please read this entire page to get all the important information you need about growing Milkweed.
When you are ready to plant, soak your seeds in non chlorinated water for up to 6 hours, then place seeds 1/8 inch below the soil surface, or even in a damp paper towel, you can use growing trays, and most types of seed starters or regular garden soil if you like.
Consider using a deep pot if starting indoors, since most milkweeds have a long roots. Don’t plant the seeds too deep, because they need plenty of light and warmth to germinate and grow ( at 70 degrees within 14 days our southern Curassavica will break the soil surface, Syriaca and Speciosa may take another 2 weeks).
Keep the seedlings moist for the first three weeks after they sprout, then transplant to larger containers with quality soil if necessary. You can lightly fertilize them lightly after the seedling stage, using a regular flower fertilizer.
Cutting off the top of the plant after they reach 8-12″ creates more stalks and more leaves. It takes about two months before the curassavica plant is large enough for caterpillars to eat.
Every type of milkweed is different and has its own growth pattern. The types we promote are the proven easiest to grow and favored by Monarchs.
When the leaves have been eaten, simply cut the stem about three nodes (where leaves came out) or 4 inches inches above the soil or just above the lowest branching of the stalk and the plant will grow back fuller and create even more food for Monarchs.
Warning: one caterpillar will eat 20+ large leaves so make sure you have enough plants to support the number of caterpillars you have, or they will starve.
When to plant depends on your location. It takes a minimum of 60 days from seeds to have a plant large enough to support a caterpillars’ food needs. You can raise our tropical Milkweed in pots inside your home or greenhouse, and it should survive the winter. If you live in a northern climate and see snow, then request the Syriaca or Speciosia variety of milkweed seed, as it survives the winters cold.
You can save your seeds till next year and start them early inside, then transplant outside when the weather warms up. Your goal should be to create a refuge of lush milkweed for the migrating Monarch and have extra plants in case of any shortages.
Once you have a good supply of milkweed, you can also purchase eggs, small caterpillars or chrysalis if necessary from many breeders to ensure there are butterflies in your area immediately or assist with the genetic diversity in remote areas. Just one mating couple and a good supply of milkweed could produce many healthy fluttering friends for your community.
Check with your local plant nurseries if you have questions about when to plant seeds or when to buy plants or transplant them safely outdoors.
COVID 19 changed so many things for all of us. Harvesting healthy milkweed seed in 2020 and 21 proved almost impossibe so we are partnering with livemonarch.org. We support them by purchasing their quality seed and packaging it for you. Tropical Milkweed plants and Common Milkweed seed available at the Sanctuary planned special events Memorial Day weekend. Seed will be available everyday of our 2024 season at the building or by mail: see below.
If you would like us to mail you 50 seeds, please send $3.00 and a self addressed stamped envelope to BMBS c/o 115 South Street, Jim Thorpe , PA 18229.