Today, my oca (Oxalis tuberosa) seed count stands at 1,022 for the year, which means that I have achieved my goal, with three or possibly four months left before the first frost. I have 123 pods maturing on cuttings indoors, which should yield about 900 more seeds by the averages and more than that bagged outdoors, which will probably produce somewhere between 300 and 1200 seeds, depending on how cooperative the weather is. Consequently, I am not doing any more hand pollinations, other than with varieties where flowers have been rare or nonexistent thus far. That will return about 2 hours per day to general garden maintenance, which is good because I have badly neglected it in order to work with the oca.
(As a side note, I wonder if I am the first to get oca seed in North America. I’ve talked recently to the few major oca growers that I know of and nobody has produced seeds. Oca is a rare crop in North America, but not that rare – the number of growers must at least be in the hundreds and probably the thousands since big catalogs like Territorial are selling it now. But, so far, I’m the only one that I know of. If you have produced oca seed in North America or know someone who has, please let me know. What can I say? It is a relatively meaningless distinction, but it appeals to my ego.)
I’m not sure exactly how many seeds that I need to get 800 plants. The low estimate is 50% germination, which would mean 1,600 seeds. I’ve sent out about 250 to other growers already, but between those yet to mature on the cuttings and those already collected, I should have plenty. In fact, I expect to collect 3,000 or more in total, because the plants are flowering better than ever and I am seeing a lot more insect activity. Honey bees, which have been absent in the oca patch so far, are now frequent visitors and much more diligent than the bumble bees. I watched one work its way down about 16 feet of row this morning, stopping on at least half the flowers on each plant. Insect pollinations will almost all be Sunset x Hopin or the reverse, but given oca’s octoploid genome, I expect considerable variation anyway.
I’m doing a crude experiment with 60 seeds to determine if oca seeds have any dormancy. I’ve soaked 20 in water, 20 in KNO3, and 20 in GA3 for 24 hours and they are now wrapped in damp paper towels stored at 70 degrees F. Hopefully, I’ll find that oca has little dormancy or that it can be broken by one of the chemical treatments. I have reason to hope for the best, as I’ve been told that some seeds sent to New Zealand from Europe germinated and were grown out the same year. If I can get some of these seeds to germinate, I’ll grow them in pots and might be able to get some tubers even with such a late start. The potential of producing early seed and then growing out the tubers in the same year could be a real boon to oca breeding efforts.
Now I have to start thinking about how to handle a big mass sowing, what my selection goals are, and how I will store and track plants. Starting, planting out, and maintaining 800 oca plants is no problem; I have more than 300 this year and they are pretty much a trouble free crop. But, if every one of those plants were unique, observing and recording the details necessary to make selections would take a lot of time. So, I will have to be very selective about my selection criteria and focus on things that don’t require a great deal of on-going observation. At any rate, it is a good problem to have.
Who knows if I will ever have such good luck with oca flowering again, so don’t be shy if you are interested in growing some. Right now I have seed to spare and it won’t do anyone any good sitting in a sack in my freezer.
So far, I have sent seeds to other growers in Washington, Oregon, California, Australia, Belgium, and New Zealand, so the oca is making effective use of me in its reproductive efforts.
Oca seeds and tubers are sometimes available in our seed shop.