A few years ago we were engaged in a USDA funded research project with the goal to establish a sustainable source of this threatened plant. Our efforts were supported by the University of Wyoming departments of Horticulture, Renewable Resources, and Agricutural Economics.
We have dicovered that Ligusticum poerteri can be propagated very successfully in two different ways; from seed and root crowns. We've put together a short "how to do it" list (see instructions). If you would like to have more information about the nuts and bolts of our research, email us atemh!@ElkMountainHerbs.com.
Considerations for Growing Osha
Consider organic certification. As this is a medicinal herb, organic roots are much more sought after and bring a substantially increased income.
Choose a location in the foothills or high country preferably above 8.000 feet, best if Aspen trees are present or near by. Otherwise, plan to acquire aspen leaves to use as mulch.
Expect your first crop in about 3 - 4 years.
Fertilizing is indicated especially after the first couple of years. The plant likes organic matter.
Pest management may not be required. Aphids may come around and live on the flowering and seeding stalks. They appear not to infest the leaves and therefore won't impede the root development. If you grow other crops, you may want to give Ladybugs a try.
Recommendations for Growing Osha from Seed
1. Obtain fresh seed stock, no older than one year old.
2. Prepare bed, remove all weeds. If possible, cover bed with plastic or organic mulch for a year before planting, to discourage weed growth.
3. Plant seeds from late September to late October, but before or between snow falls.
4. Plant seeds 2" apart in rows that are about one foot apart
5. Cover seeds with ¼" of soil. (water once after planting)
6. Start watering/irrigating the bed in the spring (late April/ early May).
7. The water requirements are approximately 700-800 gallons for a 4' x 16' bed per year.
8. After the seedlings emerge (mid-late May) weed bed carefully. The seedlings look like small parsley plants. At first emergence, they resemble tiny grass blades.
9. Water the seedlings once to twice a week, each time with about ½" or more, increase watering frequency or amount as the season gets warmer. Don't let the seedlings dry out.
Figure 1. Expected appearance of Osha (Ligusticum porteri) seedlings soon after germination.
10. Keep beds well weeded throughout the season. Not weeding may translate into a loss of 25% of your crop annually.
11. No need to shade the plants. Our experience showed, that plants (0-3 years old) grown in full sun grew a bit more vigorously, and had larger roots. We don't know if older plants benefit from shade. Consider that Osha in the wild grows best among Aspen trees where they are partially shaded. Shading (50%) may be required if you try growing at a lower altitude, where evaporation (wind and heat) and soil temperatures increase.
12. Most of the seeds will germinate the first spring, though a number of them will germinate in a staggered fashion. Some may germinate later in the season or during the 2nd or 3rd year. Therefore, we recommend harvesting by hand. Harvest the largest plants starting year 4. This will also be a thinning process, allowing more space for the smaller and /or younger plants. It may be possible that a seed-bed can be maintained and selectively harvested in this manner for 3 or more years.
Figure 2. Expected appearance of 2 year-old Figure 3. Expected appearance and plants from seedlings. root size of 2 year-old seedling plant.
Recommendation for Growing Osha from Root crowns
1. Obtain fresh crowns, dug up in the fall shortly before planting. Keep them refrigerated/in cooler temperature until you plant them.
2. Best if crowns are at least 3" long and display a number of leaf buds.
3. Prepare bed, remove all weeds.
4. Plant crowns from late September to late October. (Figure 30).
Figure 29. Size and appearance of Osha crown cuttings harvested from wild source.
5. You may want to consider treating the crowns with the hormone IBA (Indolebutric Acid) which will enhance root development. If you grow organically, check if this is permitted.
6. Plant crowns one foot apart in rows that are also about one foot apart.
7. Cover seeds with ¼" of soil. Do not plant too deep, as they will rot. (water once)
8. Start watering/irrigating the bed in the spring (late April/ early May).
9. The water requirements are approximately 700-800 gallons for a 4' x 16' bed per year.
10. The plants will emerge from late April to early May. Weed the bed carefully as soon as necessary.
11. Water the seedlings once to twice a week, each time with about ½" or more, increase watering frequency or amount as the season gets warmer. Don't let them dry out.
12. Keep beds well weeded throughout the season. Not weeding may translate into a loss of 25% of your crop annually.
13. No need to shade the plants. Our experience showed, that plants (0-3 years old) grown in full sun grew a bit more vigorously, and had larger roots. We don't know if older plants benefit from shade. Consider that Osha in the wild grows best among Aspen trees where they are partially shaded. Shading (50%) may be required if you try growing at a lower altitude, where evaporation (wind and heat) and soil temperatures increase.
14. Chances are, if the "crownlings" survived the first winter they've got it made. If you notice that some of them did not survive that crucial time plant replacement crown cuttings in the empty spaces a year after the first plating. That way you'll maximize your yield.
Figure 30. Eruption of leaf buds on crown of 2 year-old root.
Figure 31. Root mass after 2 years of growth.
15. Harvest your crop after 3 - 4 years.
Figure 32. Expected appearance and root size of 2 year-old Osha plant started from crown root cutting.
16. Keep some of your own root crowns for immediate replanting. It may be a good idea to introduce at least a few root crowns from the wild to retain healthy genetic variability, thereby increasing your crops' ability to resist disease. Or better yet obtain your crown cuttings from your own bed seedling plants (see above on "how to grow Osha root from seed"). It may take four or possibly five years for the seedling plants to generate a good crown clump. However, if you want to make friends with Osha and grow it, you will have to think ahead. It may well be worth your while .
Note: Sorry we couldn't upload the photos to go with these instructions; we are working on it...