Seed Germination

[Jim McClements, Dover, DE z6]

I sent this to Judy McCann yesterday but thought there might be some others
who'd be interested.  Jim

Judy

You've probably already gotten more information than you wanted about Arisaema
seed germination, but here comes some more, "step by step", as requested. You
experts can delete now!

The Deno paper towel method works VERY well for arisaemas. Unlike trilliums
and many other seeds, the rootlet(or radicle) is smooth and does not get
tangled in or grow through the toweling, at least in my experience of doing at
least a hundred batches of seed with this method. I check the towels once or
twice a week, and as soon as some of the seeds germinate, I plant them all.

HOWEVER, there's probably not much point in doing this unless you're  trying
to compress the growing periods. Utilizing my current method, I can usually
get 3 "growing seasons" into two years. Otherwise, I agree that using nature's
weather patterns is much easier.

Here are my steps:

1. Clean seeds are soaked in a glass of water containing a few drops of "Dawn"
dishwashing detergent for several hours (occasionally overnight if I forget
them!) This was invented by Ray Stilwell, and works as well as a longer soak
in plain water. The purpose is to remove the germination inhibitor that is
present on the seed.

2. They are then placed in the folded paper towel, damp but not wet, and then
into a "Baggie". This is put in a warm closet and checked every few days.
(write the name on the towel before you moisten it!)

3. When one or more seeds germinates, all are transferred to a pot of pure
turface which is then placed in a flat of shallow water, under lights.

4. When the seedlings appear, a very small amount of fertilizer is added to
the water in the flat.

5. The seedlings are grown on, as close to the lights as possible, until the
growth cycle is completed.

6. It is then very easy to find the small tubers by dumping the pot into a
plastic bowl. A small amount of water added allows even the tiniest tuber to
be seen in the turface.

7. These tubers are then refrigerated for about 3 months, temperature kept
above freezing. For this stage they are put in a "Baggie" in slightly damp
turface or potting mix. I've been using the turface for this recently. It
works well and makes it very easy to find the tubers after the "artificial
winter", by adding a bit of water as above.

8. You can plant the tubers as soon as they come out of the refrigerator, or
you can leave them in the damp turface until they start to sprout. The latter
approach saves some space, since it is usually 4 to 6 weeks after
refrigeration that sprouting occurs. Then they're planted in a promix/turface
potting mix and grown on under lights, but NOT in standing water. You can only
get away with that with pure turface and only with seeds.

9. After the second growth period, the tubers are harvested, bagged in damp
turface again, and refrigerated.

10. From here on it depends on the size of the tubers and where you are in the
calendar year as to whether they are planted out or grown on under lights.

There are a few species which don't conform to the above pattern and probably
should just be planted out in pots. Both subspecies of A. thunbergii seem to
want a cold period before producing above ground growth, although their close
relative, A. kiushianum, just germinated readily with a leaflet without a cold
period. A. elephas is the most difficult for me, with very few results from a
lot of seeds that have been in and out of the refrigerator. However, most
arisaemas don't need a cold period to germinate, and fresh seed will germinate
immediately using the above protocol. Some of my seed from '98 is already well
into the first growth cycle, almost ready for its first "winter" in the
refrigerator.

One other generalization, learned the "hard way", is that when it comes to
storing dormant tubers in the refrigerator, the smaller the tuber, the more
moisture is needed. As Ellen indicated in her posting, mature tubers can be
thrown into a box and stored essentially dry. However, tiny tubers are more
easily lost to drying than rot. Turface dampened just enough to make it dark,
but not wet enough to clump, seems about right. And remember that when tubers
are replanted, they'll need more water once they leaf out. Too much wetness
before they break dormancy can result in rotting.

Most of this information is spread around in the archives, but I thought it
might be helpful to have it updated, and in one place.

Jim McClements