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Milkweed - Balloon
Milkweed - Balloon
Milkweed - Balloon

Milkweed - Balloon

Gomphocarpus physocarpus

Previously classified as Asclepias physocarpa, but changed to reflect its tropical roots, this variety also has several common names like Swan plant, Balloon plant, Hairy Balls, and Family Jewels. Extremely popular in the cut flower industry for its unusual ball shaped seed pods, and the flowers, though less showy than other milkweeds, are loved by pollinators. Summer blooming. Full Sun. Perennial in the South, but please see note about tropical milkweeds. Approx. seeds per packet = 80 ( 1/2 Gram Packet)

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Average Seed / oz Seed / 100' Row Average Yield / 100' Row Days to Harvest
4800 n/a n/a 70
Planting Season Ideal Soil Temp Sun Frost Tolerance
Fall 65-80°F Full Sun Lightly Tolerant
Sowing Method Seed Depth Direct Seed Spacing Seeds Per Packet
Direct Seed 1/8" 6-8" 100
Mature Spacing Days to Sprout Production Cycle Seed Viability
24-36" 21-28 Perennial 2-3 years

Site Selection

This tropical milkweed is hardy in zones 8-10 and grown as an annual elsewhere. Prefers full sun and will thrive in dry to medium moisture soils.


Seeds can be started indoors 6-8 weeks before the last frost date. Sow seeds 1/8" deep and 6-8" apart. Optimal soil temperature for germination is 65-80˚F. Seeds will sprout in 10-28 days. Thin seedlings so that mature plants are 24-36" apart. Transplant outdoors once the danger of frost has passed.

*A note about tropical milkweeds: There is some controversy in the conservation circles about whether or not it is a good practice to plant non-native milkweeds. We at Sow True Seed believe that anything that can be planted that acts as a food or habitat plant for pollinators is a good thing to do, but we support the idea that it’s a responsible practice to cut Gomphocarpus physocarpus back before seed pods reach maturity and disperse seeds.