Ginseng Seed: What do we really know?
Part 1: Seed Moisture
May 6, 2012
Traditional wisdom was more or less simple -dry ginseng seed is dead ginseng seed. Beyond that, we were told to stratify the freshly harvested berries mixed with sand in the ground. Some advocated removing the pulp of the berries first, either mechanically or by allowing them to rot off the seed. Then, the next fall, float the seed and discard all those which float.
As time went on we started seeing the advantage of mechanical depulping rather than rotting, because botrytis and alternaria fungi are both commonly present in rotting berries. As the Internet became available to more people, and information began to flow, we recognized these fungi as two of the primary reasons why our ginseng didn't do well at times. Additionally, we began using bleach to kill fungi on the seeds before they went into stratification.
When we pulled the seed from stratification, we floated them, and then we bleached them again. I am of the mind that bleach not completely rinsed off the seed has a negative effect on germination results. I have not experimented with this, but I have observed issues with rootlets that appear to be killed by bleaching. Therefore, it makes sense to me that if stratified seed is left in a bleach solution too long, or not rinsed completely to remove the bleach, it might make its way inside the seed's shell thru the pore and cause damage to the embryo inside. I would still bleach seed right out of the box if I suspect any fungi to be present. However, I would use a weaker bleach solution (maybe 5% instead of a 10% solution) and be very meticulous in being sure the bleach is all washed off afterwards.
One of the things that have remained most constant is the concept that ginseng seed must be kept damp. Logically, this poses some quandary as cool and damp are prerequisites for fungal disease infection. Obviously, the seed needs to go through the cold, warm, cold, stratification cycle to encourage germination. Following each of these is a cool period which, when combined with damp, produces favorable conditions for disease fungi to flourish.
Since ginseng must have the cold periods to germinate, the primary question becomes whether or not we can reduce the dampness to a level at which disease organisms do not fare as well, yet the ginseng seeds survive without noticeable negative effects on germination.
The short answer: YES!
According to the Ontario Ministry of Agriculture Publication 610, green seed shouldn't be stored below 41 degrees. Doing so might delay germination. Instead, they recommend storing green seed (before stratification) at between 46 and 50 degrees. In recent years, some of the larger commercial ginseng farmers have experimented with above ground stratification. Doing so requires an ideal spot, or a climate controlled environment. Most of the large farmers have a cooler where they store harvested root prior to drying. These double as above ground storage for stratifying seeds throughout the rest of the year. For above ground stratification, Publication 610 recommends holding the seed at approximately 37 degrees from about mid August until May, and then at approximately 70 degrees until planting the following August.
The farmer from whom I get my seed (for sale and my own use), advises he has been stratifying above ground for a number of years. They mechanically depulp the berries and mix them with sand in plastic boxes. They place the boxes into the cooler where they can moderate temperatures if required. In the spring, they move the boxes of seed out of the cooler and into an open storage barn. At no time do they add water during the stratification process. The moisture which remains in the sand is all the moisture the seeds need to remain healthy. In the fall, they remove the seed from the sand, float test them, and bleach them. After the float test, the seed is allowed to surface dry and put into woven polypropylene (feed sacks) for handling. Sometimes the seed is treated with a fungicide, other times not. At this point, they get the seed germination (viability) tested and plant them.
In the past, seed dealers have advised seed buyers to keep seed in the refrigerator prior to planting. With temperatures about 35 degrees in the average frig, this could be why some growers have trouble with delayed germination. Just keep the seed from getting hot (attics, direct sun, etc) and you should be good.
The picture below is of some seed that I had left over from my fall planting. I intended to go back to the woods, but just didn't get there for some reason. There is maybe four or five ounces of seed in this box.
As you can see, the seed looks good. There are many grinning seeds in this lot.
Now, what if I told you that I completely forgot about this seed and left it in this box, behind the seat of my pickup all winter? Yup! Completely forgot about this seed until it was already quite frozen this winter. I just left it there at this point thinking I might be able to use it with experimentations for new seeder models this summer. I never expected it to remain viable as dry as it had become. In fact, I forgot about this seed again until about the end of April -after some 80 degree days in which it remained without water in the locked up pickup. Surely this seed was dead. It was absolutely dry as a bone. I suspect the whole lot would have floated without hesitation.
Thinking to use this seed as experimental material for seeder designs, I went ahead and wet it with a hose and set it aside the last week of April. What I didn't expect was that when I looked again, many of the seeds were now grinning. As you can see in that picture I took on May 5. I went ahead and float tested the seed and this is the result.
That's pretty good I think.
Basically what happened was the seed went through its second cold cycle in the plastic box behind the seat of my truck. It encountered severe drought conditions, but it remained viable. After the temperatures began to warm and I added water, the seed went about the business of hydrating and returning to a healthy appearance. Yesterday, I pulled out all of the grinning seeds and used them to reseed bare areas in my raised beds. I just went and looked, and there is a whole new crop of grinning seeds in that box.
This too is consistent with my and other's experiences of low or scattered germination this spring. Most years, my seedlings emerge within about a week or so once they start. However, this spring it has been very dry, and temperatures have been widely variable. Some of the seedlings in the raised beds started emerging about the middle of April. After a couple weeks, I was starting to think there were issues with delayed germination as some of the seeds were still lying just under the surface as if they had just been planted. They were viable, just not grinning or starting to sprout.
After a couple good rains, and leveling out of temperatures more characteristic of this time of year, many additional seeds began to sprout and the seedlings emerged through the straw. At this point, May 6th, there are still seedlings emerging in the beds. I talked to my seed supplier about this and he confirmed my finding. He had experienced the same thing in his commercial operation, and once the got some rain the seedlings started to emerge.
So what are the lessons?
There are two primary lessons which are contrary to traditional ginseng seed wisdom. The first lesson is that dry ginseng seed isn't necessarily dead ginseng seed. Further, ginseng seed that floats might not be dead.
We now know that ginseng seed can stand to be much drier than we had once believed and still remain viable and healthy. We also know that viable ginseng seed might be dry enough -has lost enough weight in moisture- to float. So, I would hesitate throwing out dried out seed. Instead, I would recommend soaking it in water first (at least 15 minutes to as much as overnight depending on how dry it is) and then letting it set overnight before float testing it. Secondly, we now know that germination can be delayed slightly (weeks) by allowing stratified seed to dry to a point.
The implications are that we can avoid favorable conditions for disease organisms by allowing our stratifying ginseng seeds to dry more than traditional wisdom would allow. This might also be an option for those who wish for some reason to try to plant in the spring. By allowing the seeds to remain dormant because of an intentional lack of water, the seed might still be able to be handled easily until it can be planted in the spring. By soaking the seed prior, viable seed will may still emerge even if it is a little later than the seed planted in the fall. However, doing this runs the risk of delaying germination for another year.
I still recommend fall planting by all means. However, this is an interesting twist which might come into play in circumstances such as my forgotten box of seed. I think I'm going to be building a small bed today and see how this seed actually does from this point on.
~Brad Watch for Part 2: Ginseng Seed Handling