Germinating, Growing and Transplanting

The easiest method for growing milkweed is to sow the seeds in the fall or winter. The cold, freezing, moist conditions help prepare the seeds to germinate. (Scroll down to the bottom of the page for clay seed ball planting instructions)

Milkweed seedlings can be started indoors in a greenhouse or under artificial lighting and then transplanted outdoors after the average date of last frost. If seeds are started indoors, allow 4-8 weeks growing time before transplanting. In an effort to improve germination rates, many gardeners place the seeds in packets made from paper towels and soak them in warm water for 24 hours prior to planting. Better germination rates are obtained if the seeds are kept moist in the refrigerator for up to a month before planting. Plastic flats can be used to start the seeds. Fill the flats with a soil mix suitable for seedlings (most potting mixes are), thoroughly soak the soil, and let the excess water drain. Sow the seeds by scattering them on the soil surface 1/4-1/2 inch apart, and then cover with about 1/4 inch of additional soil mix. Gently mist the soil surface with water to dampen the additional soil mix that has been added. 

After the seeds are sown in the flats, cover each flat with a clear plastic cover or a plastic bag to keep the seeds from drying out while germinating. Then, place the flat under grow lights, in a warm sunny window, or in a greenhouse. Most seeds will germinate in 7-10 days if the flats are maintained at 75˚F. After the seeds have germinated, remove the plastic covering from the flats. Once the seedlings have emerged, the soil should be kept moist by watering the flat from the bottom. You can water from the bottom by placing the flat in a sink or a larger flat filled with 2 inches of water until moisture appears on the soil surface. The soil should be kept moist but some care is needed to keep the seedlings from getting too wet - such conditions contribute to fungal growth that can kill the young seedlings (“damping off”). Thinning (see below) can reduce damping off.

The plants are ready to be transplanted when they are about 3-6 inches in height. Before transplanting, acclimate the plants to outdoor conditions for a few days by placing them in a sheltered location during the day and then bringing them indoors at night. The seedlings should be planted about 16 inches apart. Newly transplanted plants should be watered frequently. Add mulch around the seedlings soon after planting. The mulch holds in the moisture and minimizes the growth of competing weeds. The seedlings should be fertilized 2-3 times during the growing season if using water-soluble fertilizer or once a season if you utilize a granulated time-release formulation.

Source: http://www.monarchwatch.org/milkweed/prop.htm

Other Resources

The Florida Museum of Natural History, in collaboration with the Xerces Society, the Butterfly Conservation Initiative, and the U.S. Forest Service, has produced these educational brochures that feature information about monarchs and milkweeds:

Eastern U.S.    Southeastern U.S.     North Great Plains     Southern Great Plains

Common Milkweed Range

Please see green areas for the range of the Common Milkweed variety. If you are not in a green state, consult www.plantmilkweed.org for the milkweed variety native to your state. 

Plant Care

What’s convenient about the milkweed plant is that it requires minimal care. Once the roots are developed, milkweed will come back year after year. Flowers and pods develop normally after the first year. It is easy to control simply by mowing around the boarder of your plot. 

Around the first frost, the milkweed pods will begin to split and release the seeds that float in the air on strands of floss. We recommend that the pods be collected before seeds are released, so unwanted milkweed plant propagation will not occur. Most farmers to not want the milkweed plant growing in their fields. Please be considerate of your neighbors! The seeds can be separated from the pods by shaking the seeds and floss in a bag. The seeds then can be planted or donated to organizations such as Monarch Watch. This organization accepts donated seeds and uses them in their milkweed restoration project. The milkweed floss has excellent insulation properties and can be used to stuff pillows. The empty pods are popular with craft enthusiasts for making wreaths and other items.

Monarch Migration

In the fall, the final generation of the Monarch Butterfly migrates each year to Mexico from the northern parts of the U.S. and Canada. 

Monarch Butterfly Fall Migration

During the migration monarch butterfly depends on pollinator plants, like Milkweed, for food. Three to four generations are required to complete the northern return trip in the spring. The butterflies breed and lay eggs only on milkweed plants on the way back north. 

The eggs hatch into caterpillars and one month later, they turn into butterflies and continue their migration north. 

Decline of Milkweed through Pesticides

The increased use of “Round Up” ready crops has decimated the milkweed plant along with the Monarch butterfly – 90% reduction over the last 20 years. Farmers spray their fields with weed killer which kills all plants, then grow genetically engineered crops that are resistant to the weed killer.

90% Drop In Monarch Butterfly Population

Crop yield is increased, but at the expense of the health of the environment. By planting Milkweed plots, we can help restore milkweed and the Monarch caterpillar to a sustainable level.

Clay Seed Ball Planting

Fall or Winter Planting - clay seed balls can be simply placed on the soil surface. The clay will protect the seeds and the snow along with freeze/thaw cycles will naturally prepare the seeds for germination in late spring or early summer.

Spring or Summer Planting - for improved germination, clay seed balls should be placed in a wet paper towel in the refrigerator for at least a week. This is called cold stratification and naturally occurs in winter. Then the clay seed balls should planted just under the soil surface. This will provide additional protection from mice and birds while the seeds germinate