Asclepias tuberosa (Butterfly Weed) milkweed has attractive, bright orange flowers in late spring and is a nectar source for bees and butterflies. How to Plant Butterfly Weed Seeds. Sometimes called pleurisy root, butterfly weed (Asclepias tuberosa) is a perennial wildflower grown for its showy, reddish-orange flower clusters and textured, lanceolate leaves. It thrives throughout U.S. Department of Agriculture plant hardiness zones 4 to 10, where it is … How do I germinate butterfly weed seeds? Harvest the seed pods of butterfly weed when the pods begin to split. Seeds can be sown directly outdoors in late fall or started indoors. When sowing
Butterfly Weed Seeds (Asclepias)
Asclepias tuberosa (Butterfly Weed) milkweed has attractive, bright orange flowers in late spring and is a favorite nectar source for bees and butterflies.
USDA Hardiness Planting Zones
To determine if a plant is sufficiently cold hardy, the USDA created numbered zones indicating winter low temperatures; the lower the zone number the colder the winter.
- If the coldest winter temperature expected in your area is -15°F (zone 5) then any plants rated zones 3-5 will survive the winter temperatures in your area.
- If you live in very warm winter areas (zones 9-11) plants with zones 3-4 ratings are not recommended. The lack of freezing winter temperatures do not provide a time for winter dormancy (rest).
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Asclepias (Milkweed) are sun loving plants that are essential perennials for monarch butterflies providing food for caterpillars and nectar for adult butterflies. They bloom from mid-summer into early fall and, with their milky sap, are resistant to rabbits and deer.
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.
Planting Milkweed Seeds:
Milkweed (Asclepias) seeds germinate best under warm soil conditions. The seeds need a cold, dormant period, known as stratification, to germinate.
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).
Dry stratification is done by placing dry seed in the refrigerator for 30 or more days. A more effective strategy is to moist stratify them by mixing seed with moist (not soggy) sand in a zip-lock plastic bag and place them in the refrigerator for 30 days. After 30 days of cold moist storage, the seed’s natural chemical germination inhibitors have dissipated and are ready to sprout.
Asclepias tuberosa (Orange Butterfly Weed) – this perennial stays dormant until later in the spring than many other plants, especially when grown in pots. It’s fine to plant dormant plants; don’t up-pot them for planting later in the growing season.
Preferred growing conditions:
- Need sandy or gravelly soils (except the Clay form which does well in heavier soils including dry clay.)
- Does best with gravel mulches.
- After their second growing season, only requires deep but infrequent watering. Plant in full hot sun.
- Just a few handfuls of compost and Yum Yum Mix added to the planting hole is enough. Don’t plant into a rich, highly-amended soil.
- When planting dormant plants, water thoroughly after planting and wait to water again until the plant comes into active growth, at which time a deep watering every week or so is adequate. Take care not to overwater young transplants.
- Asclepias has a long, carrot-like tap root that should remain undisturbed after planting and should NOT ever be divided.
Preferred growing conditions:
- These species grow in a wide range of soil types, including clay.
- They don’t need mulching (except in very hot climates).
- These are moisture-loving perennials and do well in wet to moderately moist soil conditions.
- Plant in full to part sun areas.
- They like compost enriched soils at planting time.
- Asclepias syriaca and A. speciosa will spread to make big patches of plants and are best planted in parts of the landscape where they won’t crowd out less vigorous plants. Not recommended for the prime spots in your perennial beds.
- Asclepias incarnata (Swamp Milkweed) is a more refined grower and is fine to include in perennial beds.
Oftentimes, Milkweeds won’t grow much their first season in the ground, so be patient. They are establishing their root system and crown. By the second growing season, the plants will begin to get bigger and look more robust. Asclepias species are an odd bunch and don’t behave like many other more familiar perennials. So be patient and accept their quirky nature.
- Fertilize Asclepias just once in fall with Yum Yum Mix and Planters II. – Naturalized plantings don’t need additional fertilization.
- To encourage re-seeding and provide winter interest with their ornamental seed pods, leave the stems intact over the winter. In mid-spring, remove old stems just above ground level.
- All species of Asclepias are late to emerge in the spring, so don’t be concerned if other perennials come up first and they remain dormant.
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How to Plant Butterfly Weed Seeds
Sometimes called pleurisy root, butterfly weed (Asclepias tuberosa) is a perennial wildflower grown for its showy, reddish-orange flower clusters and textured, lanceolate leaves. A member of the milkweed family, it thrives throughout U.S. Department of Agriculture plant hardiness zones 3 to 9, where it is frequently added to butterfly gardens and native plant landscaping.
Butterfly weed and milkweed seed pods may be harvested and planted to support Monarch butterfly caterpillars. Butterfly weed grows well from seeds, which must be harvested in late summer and either sown immediately in the garden, or started in spring after a lengthy chilling process. The seeds are viable and will germinate with little care, although they must be planted at the appropriate depth to ensure successful sprouting.
Gather the butterfly weed seeds in late summer or autumn, once the pods dry to a light, rosy-beige color, but before they split open. Put on rubber gloves before handling the pods to protect your hands from the mildly toxic sap.
Before you begin to harvest the butterfly weed pods, sterilize your cutting tools. Dip the blades into a full-strength household cleanser, such as Lysol or Pine-Sol. Repeat between cuts to prevent the spread of diseases.
Snip off the pod using pruning shears. Slice lengthwise along the edge using a utility knife. Pry open the seed pods. Scoop out the seeds and fluffy matter inside and place it in a bucket.
Leave the bucket outdoors for two or three days to let the fluff blow away. Stir the seeds occasionally to loosen more fluff. Do not worry if some of the fluff remains, since it won’t inhibit the germination process.
Place the butterfly weed seeds in a plastic bag filled with 1 cup of moistened perlite. Store the bag inside the refrigerator for three months. Mist the perlite with water every few days to keep it from drying out completely.
Prepare peat or other biodegradable pots before removing the butterfly weed seeds from the refrigerator. Fill 3-inch starter pots with a mixture of half seed-starting compost and half coarse sand. Moisten the mix and press it firm.
Make a 1/4-inch-deep planting hole in the center of compost mixture. Drop one butterfly weed seed in the planting hole. Cover it with a loose layer of compost. Mist the compost to settle it.
Arrange the starter pots on a propagation mat near a source of bright, indirect light such as near a partly shaded south-facing window. Set the temperature on the propagation mat to 86 F during the day. Turn it off at night.
Water the butterfly weed seeds whenever the compost feels barely damp when pressed. Apply the water by the spoonful or use a spray bottle to keep from dislodging the seeds.
Watch for germination in two to three weeks. Turn off the propagation mat one week after the seeds sprout. Move the pots into a cold frame outdoors or against a south-facing wall with noonday shade.
Transplant the butterfly weed into a permanent bed in spring just after the last frost. If planting butterfly weed in clay soil, dig in 2 to 4 inches of compost to lighten the soil, or consider building raised beds to increase drainage.
Spread a 1-inch-thick layer of mulch around each plant. Water weekly to a 2-inch depth during their first summer, then cease supplemental irrigation.
How do I germinate butterfly weed seeds?
Harvest the seed pods of butterfly weed when the pods begin to split. Seeds can be sown directly outdoors in late fall or started indoors.
When sowing seeds outdoors, work up the soil in a protected location in early to mid-November. Scatter the seeds over the prepared seed bed and then cover the seeds with approximately 1/4 inch of soil. The cold, moist conditions over winter improve seed germination. Seedlings should emerge in spring. Carefully transplant the seedlings to their permanent locations when the seedlings are 3 to 4 inches tall.
To start seeds indoors, fill a flat with a commercial germination medium (such as Jiffy Mix). Moisten the medium. Scatter the seeds over the surface of the germination medium and lightly press the seeds into the material. Cover the seeds with an additional 1/4 inch of the germination mix. Carefully moisten the additional material. Slide the flat in a plastic bag and place the bagged flat in the refrigerator. Leave the flat in the refrigerator for 4 to 6 weeks. After 4 to 6 weeks, remove the flat from the refrigerator and place it in an area with a temperature of 70 to 75 degrees Fahrenheit. Seeds should begin to germinate in 3 to 4 weeks. (If no seedlings appear after 4 weeks, place the flat back in the refrigerator for another 4 to 6 weeks and repeat the process.) Take the flat out of the plastic bag as soon as seedlings appear and place the flat under fluorescent lights in a 60 to 65 degree Fahrenheit location. Transplant the seedlings into individual pots when the seedlings are 1 to 2 inches tall. Continue to grow the seedlings indoors under fluorescent lights for several more weeks. Prior to planting outdoors, place the seedlings outdoors in a shady, protected location and then gradually expose the seedlings to longer periods of direct sun. Plant the seedlings in their permanent locations after they have hardened outdoors for 10 to 14 days.