Physocarpa, Asclepias

Physocarpa Milkweed Seed

Inflated balloon-like seedpods create unforgettable garden novelty
African milkweed supplies foliage for monarch caterpillars
Tall plants thrive through warm sunny seasons
Distinctive pods excel in floral arrangements

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Key Attributes

Botanical Name

Asclepias physocarpa

Days to maturity

90-120 Days (from transplant)

Sun

Full Sun

Packet

15 Seeds

Zones 8–10 Check your growing zone

About Physocarpa, Milkweed Seed, Milkweed Seed

Asclepias physocarpa, commonly known as Swan Plant Milkweed, Balloon Plant, or Hairy Balls Milkweed, is a distinctive African species that has become popular in warm-climate gardens and butterfly habitats for over a century due to its unusual, inflated seed pods and its value as a host plant for monarch caterpillars. The plant features upright, branching stems lined with narrow, lance-shaped leaves and topped with clusters of small, white to pale pink flowers that attract a range of pollinators.

Growing details

Planting

Sow Depth

1/4"

Days to Germination

14–28 days

Germination Type

C30 - Cold Moist 30 Days

In-row plant spacing

18-24"

Plant profile

Life Cycle

Tender Perennial

Hardiness Zone

Zones 8-10

Plant Height

60 inches

Growth Habits

Upright

Seed & variety

Seeds Per Ounce

4,200

Color

Green, Pink, White

Seed Type

Open Pollinated

Before Planting

Choose a sunny site with soil moisture and drainage suited to the species, since milkweeds range from dry-prairie to wetland types. Remove competing weeds and avoid rich fertilizer. Determine whether the seed requires cold-moist stratification, then complete that treatment before spring sowing or sow outdoors in fall.

Planting

Sow milkweed outdoors in fall for natural winter chilling, or plant properly stratified seed in spring. Press seed into good contact with the medium and keep it evenly moist through germination. Indoor-started seedlings need strong light and careful hardening before transplanting. Because milkweed develops sensitive roots, move seedlings while young and disturb the root ball as little as possible.

Watering

Once established, milkweed prefers deep, infrequent watering. Let the surface dry between irrigations, supply extra moisture during extended heat, and avoid keeping the crown continuously wet.

Fertilizer

Fertilize milkweed modestly as new spring growth begins, following soil-test recommendations. Stop after midsummer so late tender growth does not reduce winter hardiness.

Harvesting

Milkweed flowers are ready when stems are firm and blooms show mature color without fading. Cut during cool, dry conditions; for seed, leave selected heads until brown and dry.

Tips

Avoid pesticides on milkweed used by monarch caterpillars. Mark young plants so they are not mistaken for weeds, and allow selected pods to mature if natural reseeding is desired.

Pests & Diseases

Milkweed may develop leaf spots, rust, powdery mildew, or viral mosaics. Minor spotting usually needs only sanitation, but persistent mottling, distortion, or stunting warrants whole-plant removal. Avoid moving symptomatic plants among pollinator gardens, thin dense colonies, and clean tools before collecting pods or propagating roots.

Milkweed can attract aphids, thrips, spider mites, Japanese beetles, and slugs. Scout flowers and new growth regularly, handpick when practical, and protect beneficial insects with targeted controls.