Germinating iris seeds
Mike Rosenzweig, Ph. D. wrote:
> I am trying to hybridize for the first time. I have collected some seed pods.
> What do I do now -- with the seeds that is???????
> Any help would be greatly appreciated.
Plant them and they might grow, don't plant them and for sure they won't
Seriously now, read the following info that was published in the CIS
Newsletter July 1995 issue. It should help you out. Good luck.
Germinating Iris Seeds
by John Coble and Bob Bauer
We have always (since 1982) germinated our Japanese and Siberian
iris seed indoors. From some of our first experiments with this
technique we had 80-100 % germination. With favourable weather we were
planting 8-12" seedlings in May with the first fan increases seen in
July and in some crosses 100% bloom the following year. Our most
vigorous seedling produced 8 bloomstalks on a one year plant!
Our main reason for germinating seed indoors is to gain one year
on first bloom and thus one year on evaluation. most important is the
elimination of unworthy seedlings and freeing garden space for another
crop of seedlings. This does become important with an annual crop
planting of 1000-1500 seedlings.
We collect our seed pods when ripe and starting to split,
usually early September. The seeds are stored in paper envelopes-but for
no more than a month. Be sure to shell your seed pods and search for and
kill any worms. As soon as all seeds are collected, the seeds of each
cross should be wrapped in pantyhose material (maybe cheesecloth would
do). These little tied up bundles are then put in a large bowl and
covered with water - a saucer on top to hold the bundles down. The water
should be drained and changed every day for at least two weeks. This
soaking and rinsing treatment is to remove the seed germination
inhibitor present in the seed or seed coat. Outdoors, the fall rains and
melting snow in winter do the same thing over a 3 to 4 month period.
After the final rinse the seeds are covered with a 10 % solution
of bleach for 1/2 hour. (10% solution created by mixing 1 part bleach
with 10 parts water) Pour off the beach solution and rinse quickly with
water a couple of times. Then cover the bowl with plastic wrap and
secure with a rubber band (do not seal with an air tight lid) or we
transfer the tied bundles to a plastic bag and secure them with a twist
tie. The bleach treatment is to reduce the mould population that will
want to grow on the wet seeds during the next stage, which is
The wet rinsed bundles in bowl or bag now need to be
refrigerated for 12 to 14 weeks. Fewer than 12 weeks will find fewer
seeds germinating. After the 12 weeks refrigeration the bowl or bag can
be removed to room temperature (kept closed and moist). Some seeds may
have already germinated in the refrigerator but most will start after
the third day at room temperature. After the third day, we get more
germination if the seeds are warmed to 90-100 degrees F. for 1/2 to 1
hour each day. You can set your covered bowl of bundles in another bowl
of hot water and let the seeds gradually warm up and cool back down. We
fill the bowl of bundles with warm tap water, let sit until room
temperature and then drain off the water until the next heat treatment
the following day.
Tall bearded irises and day lily seeds are handled the same way
through the soaking and refrigeration stages but not the warm water
treatment after refrigeration. Bearded irises germinate best at 55
Once your seeds start germinating handle them as best fits your
needs and situation. This will depend on the number of seeds that you
are handling, the size of your house and those you share the house with!
At about the fifth or sixth day at room temperature we open each
bundle and remove the germinated seed to plastic cups half filled with
wet sand and cover with plastic wrap. (separate cup for each cross) We
continue this every other day for about a week. The ungerminated seed
can then be returned to the refrigerator for a minimum of two more weeks
and then the room temperature heat treating treatment repeated.
The germinated seed can be potted whenever you want. The other
ideal of this system is that only germinated seed are planted. No trays
of empty cubes from ungerminated seed. We raise the germinated seed on
wet sand in plastic cups near a window. When we have sufficient number
of seedlings with green shoots about one inch tall we transplant them
with tweezers to seedling trays filled with a soilless seedling potting
mix. The trays are set about six inches below fluorescent lights;
ideally the bulbs are about 1 to 2 inches above the tips of the plants.
We use cool white bulbs and run the light 24 hours a day. We raise the
lights until the plants are 8-10 inches tall.
Then we let the seedlings grow to the lights and start mowing
off the tips every couple of weeks as they grow into the lights. We
fertilize every two weeks with a Miracid solution of one teaspoon per
gallon of water.
Hopefully by mid-May the danger of frost is past and the
seedlings can be hardened off outside for a week in the shade and
gradually moved to full sun. Watch these tender plants, they will
probably need watering every other day while outside, every day in the
Line out your seedlings in good organic rich soil and keep them
watered all summer their first year (and mulched). The next spring you
will have bloom.
Edited from AIS Region 6 Newsletter, January 1995 issue. Coble and Bauer
run Ensata Gardens in Michigan state and have introduced many new
varieties of Siberian and Japanese irises. With climatic conditions
nearly identical to what we have here in most of Canada, their
tips/hints on growing iris seedlings should be very helpful to most of
our readers across Canada.
Mississauga, Ontario Canada zone6b
Director, Canadian Iris Society
Newsletter Editor, Canadian Iris Society