When to plant: Soil moisture and temperature are very important when growing Milkweed. The best time to plant Milkweed is in early spring after the danger of frost has passed. If you plant seeds late in the spring, the seeds may not grow due to Common Milkweed Field Grown germination time and temperature. Common Milkweed seed doesn’t germinate over 85 degrees.
Other planting options: Place dry seed (not stratified) in seed starting soil and plant in peat pots under a grow light or in a greenhouse to germinate seeds. The success rate for this is low and more difficult to accomplish. If you choose to use this option it can take months for the seeds to germinate.
Where to Plant: Milkweed does well in open areas with full sunlight exposure areas like fields, parks, cultivated gardens, roadsides, highway medians, and road sides. We suggest transplanting Milkweed when the plant is no larger than 3 inches tall. In most cases in transplanting, the Milkweed plant will go though some shock and could lose all its leaves. This happens, don’t panic. The plant is trying to establish its roots and will eventually grow leaves again. This is the main reason we suggest planting seeds in peat pots, because Milkweed roots are very sensitive. Peat Pots breakdown over time in the ground, which allows the milkweed roots to grows without being disrupted. We found this to be the best way to transplant. If you decide to plant in plastic containers, but make sure it’s deep enough for roots to grow. If you receive a plant already grown in plastic, be careful to take out the plant and not disturb the roots.
Caring For Milkweed (Asclepias) Plants
Planting In Fall: If you’re planting Milkweed seed in the fall, let nature do the cold stratification for you! There is no need to place your seeds in the refrigerator before planting, you can plant seeds directly into the soil after there have been a few frosts in your area. This allows for the seeds to remain dormant for the winter and come up in the early spring. Clear away any existing growth and using your index finger to measure, create 1.5" holes for each Milkweed seed. We recommend spacing seeds about 4-6” apart. Place a seed in each hole and cover. Water thoroughly.
Light Requirements: For the next few weeks, make sure the Milkweed is either in a sunny window, in a green house or under a grow light. Milkweed needs lots of sun and warmth to grow. If you’re using a grow light, make sure to lower the bulb closer to the pots or your seedlings may become leggy, as they stretch to the light. In our experiment, this happened to us. Ideally a sturdier stem is better. Cold stratified seeds should germinate and sprout within 10-15 days once planted. In total Milkweed from the day they are cold stratified to growth can take 40 plus days, so be patient!
Butterfly Weed (Asclepias tuberosa) is one of our great North American native flowers with rich Indian and medicinal history. The brilliant orange blooms light up meadows dramatically, and of course, visits by butterflies are a bonus. This wildflower, also prized as a garden perennial, is not easy to grow, but once established, is a tough, dependable colormaker.
Germination: To start Milkweed seed we recommend starting inside, but before this happens Milkweed seeds need to go through a cold stratification period. Cold stratification is very important for the germination and growth of Milkweed. It helps break the seeds natural dormancy cycle. To do this, we recommend placing Milkweed seed in a damp paper towel or damp sand in a zip lock bag and place in your fridge for 3 – 6 weeks (30 days). Place in an area of the fridge, where it won’t get damaged. We taped ours to the bottom of a refrigerator shelf.
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Asclepias can be divided into two groups for plant care; Asclepias tuberosa with orange (sometimes yellow) flowers and all the other species with pink (sometimes white) flowers.
They can be successfully seeded outdoors in fall in areas that received frost, for spring germination. For mid to late spring planting, all species (A. tuberosa, A. syriaca, A. sullivantii, A. incarnata) will also germinate moderately well when seeded into warm ground after being stratified (chilled).
Milkweed (Asclepias) seeds germinate best under warm soil conditions. The seeds need a cold, dormant period, known as stratification, to germinate.
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Additionally, native milkweed plants in the range of monarch butterfly migrations die back after blooming. Mexican butterfly weed however, does not die back, which can lead to dangerous health problems for monarchs.
While Mexican butterfly weed can certainly sustain monarch caterpillars, its perennial growth leads to problems with migration patterns and health. Considering the fact that monarch butterflies are experiencing a steep decline in population numbers, it is important to consider the protection of this iconic species.
Asclepias curassavica is commonly known by many names, including Mexican butterfly weed, bloodflower, and tropical milkweed. The milkweed genus, Asclepias, is named for the milky substance that the plants exude when cells are damaged. Mexican butterfly weed is native to the American tropics and can be found throughout North America as an ornamental plant. It produces eye-catching orange and red flowers in flusters at the tops of its stems. These blooms are strong attractants of a variety of pollinators.
Facts, Benefits & Uses of Mexican Butterfly Weed
Mexican butterfly weed produces beautiful orange and red blossoms that are very attractive to butterflies. For this reason, it is a popular choice for pollinator gardens, bringing in bees, butterflies, moths, and even hummingbirds. However, planting Mexican butterfly weed outside of its native region, especially in range of monarch butterflies, is often highly criticized because of its negative impacts on monarchs.
Mexican butterfly weed is a controversial plant: although it can be a beautiful addition to some gardens as a food source for butterflies, it is believed to be harmful to monarch butterflies in particular. Asclepias curassavica can grow later in the year than native milkweed species, prompting monarchs to breed at times when they should be overwintering.
Like other members of the Asclepias genus, tropical milkweed has a unique mode of pollination. The center of each flower contains structures called hoods, which in this species are the yellow/orange portions of the flower, while the red portions are the actual petals. These hoods contain pools of nectar to draw in pollinators, and at the base of each hood is a smaller structure called a horn. These horns are very steep and slippery, causing any insects that land on them to essentially slip down into the center of the flower. This insect will then come into contact with the plant’s pollen sacs, which come in pairs; each pair of pollen sacs is connected by a thin, stringlike structure called a translator arm. The insect will essentially fall into the translator arm and break it, allowing the pollen sacs to be freed.