Poor germination rate.
"I have grown different varieties of milkweed from seed for years. Have many varieties in the yard for Monarch weigh station. Some of these have come from American Meadows, a favorite site to order seed. This year I chose the Spider Milkweed because it is an early bloomer for the earlier passing through of Monarchs. A little disappointed with the germination rate of this one. Out of the packet of seed only six germinated after stratification. Way less than 50%. Normally, I can expect at least 50% or better. Either seed not viable or an extremely tough variety to germinate. Six is enough to start and collect seed for the future, providing they survive. However, would have preferred a stronger start."