I’ve been trying since 2011 to get viable fig seed by hand pollinating main crop figs with pollen from persistent caprifigs. There isn’t much information on the procedure and it’s been trial and error. I finally got seed to germinate in 2013.
Common figs do not need pollination to ripen fruit. Smyrna figs do need pollination to ripen fruit, and so need to be grown in a mild area that supports the pollinating wasp.
To breed Common fig trees, it is necessary to use persistent caprifigs. In 2007 I ordered three persistent caprifigs DFIC 6, DFIC 8 (Enderud), and DFIC 126 (Caprifig Q) from UC Davis. In 2011, one of the caprifigs, Enderud (DFIC 8), produced a breba crop, and I made some crosses with the excellent, very hardy, short season fig Florea. I documented the procedure with the intent of posting when I had seedlings. But none of the seeds from the pollinated figs germinated. I contacted Dr. Louise Ferguson at the University of California Pomology Department to get some guidance, and she referred me to the gentleman, Jim Doyle, who actually did the fig pollination procedures. Mr. Doyle worked for the university for 36 years in several tree fruit variety development programs – as he put it “right where the rubber meets the road”, and after retiring from UC in 2001, he continues to work with a nursery breeding figs. He kindly reviewed my procedure and sent this reply:
“Sorry to hear of your fig development problem. From the information you sent, it would appear to me to be a germination problem rather than a pollination problem. The method of pollination that you described would seem to me to be effective in setting hybrid seed. The fact that you got seed to sink in the water after fruit fermentation would seem to indicate that seeds with embryos were present. If you have any of this seed left, you could double check by crushing a seed or two and seeing (probably under a magnifying glass) if there is white or cream-colored embryo tissue present rather than the seeds being hollow. With regard to pollen collection, pollen is usually ready when the ripe caprifig colors up and takes on a wilted feel when you squeeze it. Then, when you cut open the caprifig the anthers have dehisced and the pollen can easily be knocked out of the fruit onto a collection surface. Collected pollen can be kept for at least three weeks in a refrigerator without much loss of viability. I usually keep it in a small glass flask stoppered with cotton. In my experience, seed set can range from about a hundred seed or so up to about 900 hybrid seed per fruit.
“With regard to germination, I have always germinated fig seed at high humidity at a temperature of about 75 to 85 degrees. I have an East-facing sunroom with regular daytime fluctation up to those temperatures. I use small domed (covered) flats that act something like a terrarium to get the high humidity. Depending on the time of year that I plant the seed, I might also use a heating pad under the flats. Using this system, the seed is usually up in ten days. I use a thin layer of potting mix in the bottom of the flat overlain with medium grade vermiculite, all in a moist but not too wet condition. I scatter the seed on top of the moist vermiculite and then cover it with another thin layer of dry vermiculite and then mist the top to get everything moist. The flat is then covered and only rarely needs to have water added until germination occurs. Once the seedlings are up (usually in a two or four-leaf stage) I pick them out individually and transplant into small containers that will allow them to grow to 6 to 8 inches. From there they can be put into a nursery row, a larger container, into a field seedling row or other - as you prefer.
“I hope this information is helpful and wish you the best of luck in your project”
In 2012, Enderud fruited heavily and I tried again. The other two persistent caprifigs, while also very vigorous, produced no fruit. This time I also pollinated some main crop San Pedro figs (Fico Gentile, Fiorone di Ruvo, Grantham’s Royal) that require fertilization to ripen their main crop. I figured that main crop San Pedro figs ripening would verify that my pollination technique was working if I failed to get seedlings again from the Florea crosses. While the Florea seed sank in water after fermenting and had white embryo material inside, again none germinated. The San Pedro seeds didn’t germinate either.
In 2013 I finally got germination of seeds from a pollinated Fiorone di Ruvo.
I’m not positive, but I think that the failure to germinate resulted from pollinating figs that were too large. I generally pollinated the larger figs on the tree. Seed embryos were being formed, but I don’t think they had time to mature. Ripening in a fruit like an apple is linked to the seeds’ maturity. Common figs on the other hand ripen without seeds. (What we call “seeds” in Common figs are actually just empty seed cases called cenocarps.) My best guess is that the figs ripened before the seeds did. I think this might explain the failure of Florea to form germinating seed. Florea ripens so quickly that perhaps the seeds don’t have time to mature. I’d be glad to hear any other possible explanations.
Below is the pollination procedure:
Nature basically takes care of the timing – the caprifig brebas produce pollen when the main crop figs are ready to be pollinated. Choose figs that are about 1/3 the size of a ripe fig of that variety.
These are the tools that were used. A plate to catch pollen, coffee stirrer “straws”, sharp knife, awl (punch or other sharp, sturdy implement), and a disinfectant, hydrogen peroxide. I had used 70% alcohol, but it didn’t help to remove sap and I suspected that it caused additional damage inside the fig. I also found having paper towels and steel wool to clean sap off the awl necessary if pollinating more than one fig.
The amount of pollen in the persistent edible caprifigs varies. Some have quite a bit in the eye area, others almost none.
Split the figs, tap or knock the pollen onto a plate and “line it up” to make it easy to draw it into the straw, which in this case is a hollow coffee stirrer.
The main crop figs to be pollinated are very hard, and I found a needle was difficult to push through. An awl, sharp punch, or other sharp sturdy implement is much easier to grip and provides a larger hole for pollen to enter. Make sure whatever you use goes completely through the fig – you need two holes to be able to blow into the fig. Only pierce and pollinate one fig at a time. Once the implement is removed, the latex sap quickly seals the holes and trying to blow into the fig becomes impossible.
Bend the coffee stirrer about 90 degrees to allow the pollen to be drawn into the straw, but prevent it from being sucked into the mouth. Gently draw pollen into the straw, move it to the hole in the fig and blow it in. Loosely tie a bright colored string around the neck of the fig and tie a tag above that with information about the cross. It is difficult to keep track of a pollinated fig in a tree full of figs, so this step is important if you don’t want to accidentally pick and eat a fig that you have pollinated.
Pick the figs when dead ripe. I’m going to leave the Floreas on until they drop this year. Ferment the pulp in water as you would tomato seeds. It isn’t necessary, but pectic enzyme solution can be purchased at a wine making supply store to hasten the process. Once the seeds are cleaned, sow.