Thank goodness, spring planting chores are slowing down. We can stop, smell the roses, and start looking for seeds to save. Iris will set seed on occasion. The flower drops away and a green bumpy pod grows in its place. Iris seed is easy to grow when you follow a few simple steps. Iris are also a good candidate for hand pollination. "The Story of Iris Part 10 — Breeding Iris" by MitchF tells you how to create your own hybrid, as does "Hybridizing" on Schreiner's Iris Gardens website.
An iris seed pod is first a green bulgy thing where once was a flower. You may get one, or no, or many, pods per clump of iris. The pods will take a few months on the plant to fully ripen and dry. The pods must stay on the plant. (Beware of helpful friends who want to deadhead for you!) Will you want to know which pod came from which iris parent? Label the pods. I used a piece of cloth "athletic tape" and an ink pen to make a flag on the stem of this iris pod. With a spontaneous cross, you only know one parent plant for sure. Let the pod stay on the stem until late summer when the pod is brown and starts to split open. The seeds should be dark and shiny. At that stage, you can gather the seeds and store them dry in an envelope. Look out for any tiny insects in the seeds. Margie Valenzuela, writing for The Tucson Iris Society, says iris seed can be stored for 18 years and still grow if given the right conditions.
Iris seeds expect "winter." a cold and damp period before sending out shoots. Schreiner's Iris Gardens advocates using "nature's way" of growing iris from seed. After gathering the seed, keep it dry until fall. Nothing would be gained by putting seed in the garden or pot well before the necessary cold period. You may simply plant the iris seed in the garden, timing it to allow two (or better yet three) months of damp cold, and see what you get the following spring. Shcreiner's suggests planting at 3/4 inch depth and an inch apart. Baby iris will look grass like but soon show the characteristic flattened iris growth style. For more security plant in a pot with moist potting soil, and leave the pot out for the winter. Make sure the soil stays moist in the pot. You may cover the pot with plastic mesh to keep out beasts. Pesky squirrels seem to like to bury nuts in pots of fluffy potting soil. Your baby iris won't bloom the first year they sprout but might flower the second. Blooms are likely by the third year.
These Siberian Iris pods look promising, at right
Helping mother nature
Nature's way of germinating iris seed should yield 50 percent or more germinating the first spring. Remaining seeds can germinate in the years afterward. You can boost the germination rate with a more hands–on treatment. The seeds have a hard coat and contain hormones that prevent sprouting at the wrong time. Both of these factors can be overcome with a good soak in plain water. Soak the iris seeds at room temperature covered with a small amount of water to ready them for fall planting. Following Margie Valenzuela's plan, soak at least two days and up to two weeks. Rinse the seeds and change the water daily during this soak. Plant seeds a half inch deep and apart in a seed starting mix type pf soil.
Even more hands-on approach, growing indoors
The article Germinating Iris Seed, by John Coble and Bob Bauer, appears on the site of the Canadian Iris Society, The authors detail an even more controlled method. This method allows them to efficiently process a large amount of seeds and more quickly see the results of crosses. This method is not technically challenging but I think listing it as steps will help clarify. Follow the link to read the full article.
- Soak the seed as above, for two weeks and changing the water daily, With multiple pods, use thin mesh like pantyhose material to seperately bundle the types or crossed varieties of seed.
- Use a sterilizing rinse. Pour off the water and immerse seed in a solution of one part bleach and ten parts water; let stand for a half hour. Then pour off the bleach water and rinse briefly with clear water.
- Store the wet seed, still in pouches, in a plastic bag. Refrigerate for twelve weeks.
- Move the bag to room temperature, and check for germinated seed. As seeds germinate they can be placed in seedling mix and grown under lights indoors.
- Grow the seedlings, indoors under fluorescent light, using a weak fertilizer. As weather permits, move the seedlings to a rich prepared garden. Keep them well watered for the first year. You should see first bloom earlier with this method than you will with the "natural" way.
Keep iris seed moist at all times once you start. While the seed can be kept for years dry, once you start the germination process, best results depend on constant moisture.
The cold period followed by warm should stimulate the seed to sprout. If new sprouts are not appearing , you may chill again for two more weeks; this may stimulate more germination.
~~ Resources ~~
Schreiner's Iris Gardens http://www.schreinersgardens.com/hybridizing.shtml
Tucson Iris Society http://www.tucsoniris.org/articles/iris_from_seeds.php
Coble, John and Bob Bauer, Germinating Iris Seed Canadian Iris Society, http://www.cdn-iris.ca/seeds.html