Annual
about 100 seeds per packet
 
Japanese indigo, Persicaria tinctoria, is one of the indigo-producing plants that does best in temperate zones. Dye directly with freshly picked leaves on silk and wool, or extract the pigment for vat dyeing. A vigorously-growing annual, this plant is so much fun to grow and can be harvested several times per season. 
 
Start seeds indoors and transplant groups of 2-5 seedlings at 1' spacing outside after danger of frost. Japanese indigo likes plenty of water and nutrients. Plant with compost and add fertility after each cutting for best results. I generally begin harvesting the leaves when plants are around 12"-18" tall.