Germination

Lowell, I doubt that ANY of us has figured out the BEST method of
germination, but it is a constant adjusting of old methods and trying of
new methods.  In my limited 49-year-experience with planting bearded
iris seed, here are a few thoughts/opinions.

I plant in pots, as I am a fanatic when it comes to keeping cross
records straight.  If you plant directly in the ground, there will be at
least a limited amount of delayed germination in following years,
contaminating the newly-planted crosses.  Seed bed soil would have to be
removed and replaced, or soil sterilized.

Seed is planted in late fall, so as to avoid any pre-winter germination
if possible.  That meant November in northern California, October here
in Oregon, as I also want to avoid doing it once the weather turns
nasty.

Pots are clustered, but not buried.  Were I in a colder clime, I would
do something to insulate the pots somewhat.  The ONLY time I have had a
problem was one year in California....record cold down into the high
teens at night, not thawing for several days....in February, after the
seed had been germinating for over a month.  All sprouts up were fine;
but practically nothing else came up except a few stragglers, and those
tended to be very late in the season.  It was if the
germinating-but-not-emerged seed/seedlings were at a critical stage.  I
wonder if anyone else has had this experience?   I now have the pots so
I can hastily cover them with woven plastic ground-cover cloth if there
is a serious cold snap.

Germination in California  (TB seed) would run from 25% to 85%, in
almost direct relation to the amount of winter cold we got.  (The low
figure being winters when we had almost no frost.)  It must be kept in
mind that both timing and percent of first year germination will vary
greatly with the type of iris, and the genetic background.  For me,
dwarfs and luminata TBs, white-ground or tangerine-factor TBs, tend to
be the earliest to germinate;  latest and hardest used to be the Mary
Randall derivatives, the old-time recessive amoenas and blacks,
variegatas.  Generalities only.  And, we are now ca. 25 generations from
species and lines are so intercrossed, there seems to be somewhat less
variation.

It is important not only to keep the seed moist, but to provide
leaching.  I use a very sandy mix, and if there is not much rain, I
water the pots even tho they are still damp.  (Alfalfa pellets are
incorporated into the soil in the lower half of the pot, to provide some
substance, nutrients, to make up for the sandy soil.)

In comparing the germination rates on Marky's crosses the two years they
were germinated here, you have to consider several factors:  Salem gets
more rain (more leaching);  Yakima gets more cold (which should be a
plus in breaking dormancy); but the soil mixes used were NOT the same.
Yakima gets much less winter precipitation, the soil mix Marky was using
was not as sandy....and I feel the lesser leaching was a big factor.
She is trying a sandier mix this year, so it will be interesting to see
what happens....

Keith Keppel
--- in soggy Salem, OR, where it is now raining (surprise!!) and
approximately 2% of the 15,400 seeds planted last October have already
germinated.

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