Stir-Frying Ironwood Seeds

Excerpted from "Germinating Ironwood Seeds: An Olympic Event," by Carol Zimmerman, Horticultural Communicator, 1998.

Ironwood seeds are ready to harvest in June and July, but difficult to gather since the seedpods burst open and discharge seeds onto the ground when they are ready instead of politely waiting for you to take them.

I received conflicting advice on germinating seeds. Some said to wait a year after gathering seeds to plant them, and others said to plant them the same year. Almost all the advice was brutal:
Dip the seeds in sulfuric acid
Stir-fry the seeds for 3 minutes
Put the seeds in boiling water then pull them out
Soak them in bleach for 10 minutes
Rough them up with sand paper
Nick them with a knife
Soak them overnight (I did this with rainwater)
Put them in a jar with sand and gravel then shake the jar
Feed them to a bird and then follow the bird around
Put them in the ground and wait

I gathered a cupful of seeds in 1996 and again in 1997, and divided the seeds into 2 piles accordingly. I then subdivided each pile into 7 others based on the methods I intended to use. (I opted out on the acid, shaking the jar, and following the bird). There were about 30 seeds in each group, and I kept all 14 groups in the greenhouse.

The results were dramatic. Within one week, two of the "1997 Bleach" seeds had germinated. The tender cotyledon looked plump and green in spite of the cruel way I had forced their emergence. None of the other groups showed any activity.

By the second week there were six "1997 Bleach" seedlings up, three "1996 Bleach," one "1997 Stir Fry," one "1997 Plant and Wait," seven "1997 Soak Overnight," and thirty-five "1996 Stir Fry." I had 100 percent germination by stir-frying year-old seeds! There was still no activity from the other groups.

By the third week I still had six "1997 Bleach," three "1996 Bleach," one "1997 Stir Fry," thirty-five "1996 Stir Fry," and one "1997 Plant and Wait." The "1997 Soak Overnight" had increased by one, so now I had eight. Again, there was no activity from the other groups.

By the fourth week no new seedlings emerged; however, I lost some of those previously germinated. The "1996 Stir Fry" were down by five, and I lost two of the "1996 Bleach." I did not believe I would have such luck, and thinking that not all the seeds would come up I planted several to a pot. When all the "1996 Stir Fry" germinated they choked each other to death. At the same time, I was having trouble with a root fungus. If ironwood seedlings get too damp they suffer from damping-off, a seedling fungus. I lost some seedlings to this fungus. The roots need to dry out between waterings. I had these planted in one part decomposed granite, one part sand, and one part potting mix, which I thought would be adequate. I have since learned that planting them in perlite or vermiculite to permit drainage is probably wiser. Over the next several weeks I lost all but two of the "1996 Stir Fry."

Some seeds just did not germinate at all. Roughing them up with sand paper, nicking them with a knife, or quickly dipping them in hot water was not enough to inspire them. Of the estimated 400 seeds I planted, 12 small trees survive: six "1997 Bleach," four "1997 Stir Fry" and two "1996 Stir Fry."

Maricopa County Master Gardener Volunteer Information
Last Updated July 28, 2003
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
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