Starting Indigo Seeds Indoors Versus Outdoors

Q: I have some indigo seeds and I cannot find any information about starting them outdoors. Do I have to soak and start indoors? I live in northern California and there is no frost and it is nice and sunny. Can I plant them outdoors this week?

A: I'd recommend starting the seeds indoors and keeping a tight eye on the water levels (DO NOT LET THE SEEDLINGS DRY OUT).

I've never directly sown the seeds outdoors but that could work as well, as long as you maintain good moist soil. The overnight soak will definitely help to kick-start things. I've found that pill-bugs LOVE to eat the young leaves so be wary of that and set some traps for them if you can. Over-plant, then you'll want to thin to about 10"-12" on center for your final density of plants.

Here in Los Angeles my plants volunteer from fallen seed of last year's crop. My plants start to grow in December when the rains return and they are almost ready for the first harvest of leaves in May. I think you could get onto a similar cycle up there as long as you never get frost.

When to Plant Indigo Seeds

Q: I have seen in many articles that that Indigo Persicaria Tinctoria is sensitive to frost. When should I plant my indigo seeds?

A: I live in Los Angeles and I germinate my indigo seeds in late December/January under a grow-light and transplant in February. However there is NO frost in Los Angeles. If there is even a tiny frost, it will kill the plants back to the root (or thick stems if the plant is more mature). I'd recommend waiting to transplant until there is zero chance of a frost. Seeds could be planted 6-8 weeks before transplant.

Indigo Seed Propagation

Q: I grew some indigo plants, can you tell me how to propagate seeds from my plants?

A: In Los Angeles I’ll start harvesting seeds by the middle of July, but if you are in a colder climate like the northeast, they don’t typically mature until around Thanksgiving.  I do this by rooting any stems that are flowering in water indoors and letting them complete their cycle out of the soil, which they’re surprisingly happy to do.

I trim my seed bearing stalks from plants as the seeds mature and bundle them and invert them and hang them to dry.  Birds and mice love to eat the seeds so make sure to dry and store them out of reach!

Once the stalk is crispy, I will stomp or hand crush all the seed groups and begin sieveing things to remove leaves and stems and dried flower bits. I then roll the seeds between leather sheets to strip them clean, though this is not necessary for germination. I’ll then wind winnow what remains to separate the lighter and immature seed from the bulky growers!  I germinate in bulk trays and thin/transplant as needed.