After the seeds germinated you have to be very careful with light because the seedlings cannot handle much at this stage. You can increase your results, although some seeds inevitably will be duds. However, not all growers like to do this.  Source: <a href=https://nmjm.wordpress.com/2013/06/27/butterfly-weed-seeds-butterfly-milkweed-seeds/>https://nmjm.wordpress.com/2013/06/27/butterfly-weed-seeds-butterfly-milkweed-seeds/</a>