Hey cvlover,
I haven't worked much with Heli. Mostley Neps.
I just do what works for me. I'm sure there are other methods that work just as well and maybe better. One thing I do know is that if I say "this is the best way" I'll be proven wrong tomorrow and probably by myself: -)
I was lucky to enough to be able to experiment for a couple of years with seeds that were handled in pretty the same way when harvesting. The seeds were very clean to start with and the plants were grown in a greenhouse. Also the seeds were fresh and I knew the exact harvest date. So, that took out many of the variables that mess things up when trying to figure out what works.
Those seeds were all lowland species and this is what I found out works best for them/me, emphasize “for me”.
The highest germination rate and ratio of clean seeds was from a 12 hour soak using 380mg/liter of NaDCC (99%) with 10 grams of sugar and few drops tween 20. Contamination was very rare. With most batches there was none. Again, those are about the cleanest seeds one could get. The pods were unopened at harvest time and for a while the pods were even treated with isopropyl alcohol before shipping.
With seeds off of eBay the results vary a lot. Generally, those seeds are very “dirty” and you can’t always be positive of the harvest date. Throw in how each species handles NaDCC, how the seeds were handled before they are shipped, was it dry or rainy when harvested, were the pods partially opened when harvested along with questionable harvest dates, it’s no wonder that someone starting out with those seeds has hard time figuring out what works.
There’s a very good chance that 380mg/liter of NaDCC for 12 hours will not do so well with seeds off of eBay and you have up the time or adjust the amount of NaDCC higher or, lower the amount of NaDCC with more time. Plus, adding 10 to 15 minutes in 3% H202 is usually required for seeds off of eBay. With my last batch of seeds off of eBay, a 4 hour soak in distilled water with 10 grams/liter of sugar, then a 12 hour soak in 380mg/liter of NaDCC, plus 15 minutes in 3% H2O2, worked well with good germinate and low contamination.
If I get a lot of contamination from seeds off of eBay I know that the seeds were not handled or harvested in the best way.
With side by side tests the germination rate with 8% PPM + 1/4th MS for 2 hours was considerably lower than NaDCC. Maybe this is not an optimal amount of PPM and the amount of time was not optimal. So, take that with a grain salt. Also I was testing very clean, lowland seeds. The table may turn toward PPM with other types of seeds and less clean seeds. I’m not sure. Bigbella has very good success with it and I’m sure has worked with more types seeds than I have.
Disinfecting Nep seeds.
Frank