Answer: If you allow the seeds to ripen you can plant them. Not all of the seeds may be viable so I don't know how many new plants you might get. And, there's no telling what kind of iris will grow from the seeds. They were cross pollinated and may turn out to be something quite different than the parent. And, it can take several years for a plant grown from seed to flower. We usually recommend you cut off the flowering stem before seed pods develop. This way the energy will be redirected into the plant rather than be wasted on developing seeds. But, it's your call.
Iris seeds can be planted at any time, but the best time to plant the seeds is during the fall/winter/ and very early spring months.
First, soak the seeds in water for at least 48 hours or up to 2 weeks. Change the water out daily using a strainer to catch the seeds (so as not to lose any).
I've found it best to plant the seeds into pots filled with potting soil. Plant them about a half inch deep and preferably at least a half inch apart. Some people prefer to sow the seeds directly into the ground in the fall/winter, and let the natural cold of winter and nature itself wash the inhibitor factors out of the seed. And that will work too.
After the seeds have been planted keep the soil moist, (not wet) at all times to insure germination.
Best wishes with your irises.
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