HYB - TB: Reg. 7 Irisarian Reprints #13
- To: Multiple recipients of list <i*@rt66.com>
- Subject: HYB - TB: Reg. 7 Irisarian Reprints #13
- From: "* D* S* <g*@ccast.com>
- Date: Sat, 3 Jan 1998 18:56:59 -0700 (MST)
> A series of articles reprinted from the Region 7 IRISARIAN with myself as
> Editor in 1990-91. [Gary Sides--Jan. 1998: Posted to Iris-L]
>
SEED GERMINATION
Allan Ensminger Lincoln, NE
A lot of time and effort goes into producing iris seed with the intent that
this seed will produce beautiful new irises. The goal then should be to
nurture the seeds by a method that will result in 80-85% germination the
next spring after hybridizing.
This short article will propose a method to accomplish this if your garden
is in Lincoln, NE. I'm not sure how it will work in Region 7. The method
is based on the premise that iris seeds will respond to two things: 1)
Moisture - or lack of it, 2) Soil temperature.
MOISTURE--As you know, iris seeds do not want to germinate 85% the first
year after planting. If you should plant the seed in the Fall and then
stand aside and wait for germination the following spring, you may get
10-40% germination depending upon the amount of precipitation from the time
of planting until the time for germination.
The Creator of all things "bright and beautiful" had a plan to preserve the
iris specie despite any catastrophy that might destroy all the irises in
one growing season. There would be residue of ungerminated seeds remaining
in the soil to begin growing a second or third year after the seed dropped
from the pod. Now this is good for the iris specie but not so good for the
iris hybridizer who wants 100% germination so he can achieve his goals
quickly.
The delay in germination is accomplished with an inhibitor that is in the
iris seed coat. This inhibitor must be washed away. One way to accomplish
this is to water the seed bed every day that the soil isn't frozen from the
day the seed is planted until the day the seedlings emerge from the soil.
Remember that Bearded iris seed will rot if exposed to standing water for
lengthy periods of time. Constant watering works only if the iris seed bed
has good drainage.
SOIL TEMPERATURE--Our experience leads us to believe that iris seed require
soil temperatures below 50* F to germinate and the longer the soil
temperature in the seed bed can be maintained between 32* and 50* the
greater the amount of germination. Here in Lincoln the seedlings begin
emerging about April 21 and if germination hasn't taken place by May 5th,
it won't for that year. Years ago, an experiment with seeds planted May
1st (after several weeks storage in our freezer) and watered diligently
during spring and summer resulted in no germination until late November.
We attempt to partially control soil temperature with a mulch of pine
needles applied in late November and removed in early May after the seed
has germinated. The pine mulch not only shades the soil, but also slows
the evaporation of the moisture and provides a min-climate where soil
temperatures are lower than the surrounding area. As you know, evaporation
requires heat and as the moisture evaporates from the seed bed surface, the
soil becomes cooler. Sometimes, if early spring days become overly warm,
we water the seed bed at noon.
My procedure for growing irises from seed that works in Lincoln, NE:
1) August 1 - Harvest TB seed and store in cloth bags.
2) Sept. 15 - Cultivate seed bed, add goodies and treat soil with Vapam.
3) Oct. 10 - Plant seed 3/4" deep, 4-5 seeds/in. of row, rows 8" apart.
4) Oct-Nov - Water seed bed every day that it doesn't rain. I use 5 gal.
of water sprinkled on 100 sq ft of bed (4' x 24').
5) Thanksgiving Day - Cover the bed w/4-6" of pine needles.
6) Mar. 15 - Resume daily watering.
7) Apr. 21 - Peek under mulch to see if seedlings are emerging.
8) Apr. 25 - Remove top half of mulch leaving about 2" of mulch covering
bed.
9) May 1 - Push mulch to the center between rows so seedlings have
light to grow.
10) May 20 - Remove mulch, water only as necessary to keep seedlings
growing.
11) June 15-July 1 - Plant out the seedlings with space sufficient for two
years growth.
Now you know one way of growing irises from seed. With experience, yours
and that of others, you will develop a method that works best in your own
back yard.
