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Hybridizing Begonias – Don’t be afraid to try!

by Brad Thompson

Don’t be afraid to try hybridizing a new variety of your own; you learn by trying.

Not everything you create will be worth saving but you will gain a lot of experience. In fact, don’t be surprised if the first couple of years you don’t really get anything you expected or something really worth saving(that’s the experience part.)

Hybridizing Begonias: Before you get started I’ll let you know about a couple of rules and some rules of thumb.

First of all, you will have to learn how to grow from seed. It’s not that hard but crucial. Get some seed from someone and start learning now so you’ll be ready when your seed is ready. Semp seed is good to learn with and readily available.

Make sure you keep records so you can keep track of what you are doing; it’s very important. Also you will have to learn how to part with the ones that don’t pan out. You have to destroy them. You shouldn’t circulate them because it will confuse things and you don’t want inferior plants spread around. If you create some you think have merit, you can give cuttings to friends to test grow but make sure they understand that, if you decide not to release them later because they don’t turn out as well as you thought, they will have to let you destroy them. If you do a cross and give the seed to someone else, that person has the right to name the results. I try not to give out any of my hybrid seed unless I don’t plan on growing it myself because whoever I give it to might end up with plants just like the ones I grow and want to name. If we both name them, it will be confusing with two similiar plants with different names.

It helps a lot to study and find out which crosses have already been made so that you’re doing something new. “Begonias, The Complete Reference Guide” has numerous hybrids listed with their parents. Besides learning what crosses have been done already, you will also get an idea of what to expect when using a certain plant for a parent. For example, there are several crosses between dregei and canes listed and the results were small canes that branched well. By realizing this you will know what to expect if you cross dregei and Irene Nuss.

If you want to do a cross with B. ‘Irene Nuss’, then just browse through the listings and see what, if anything, has been crossed with B. ‘Irene Nuss’ and what, if any, plants came out of it. If a lot of fantastic plants came out of it, chances are it will be a good parent for crosses you want to do. You want to see if the desirable traits that you admire in the parent are passed on when it’s crossed. Maybe you want to cross with it because it has very sturdy canes or a nice color of flower. Just check its children and see if any of them have the same traits and, if they do, then these traits could also be passed on in crosses you do with it.

The opposite is also true, if there are any bad traits, check to see if those were passed on too. For instance, if the parent is leggy and hard to make into a nice show plant, the children could very well turn out that way too. It can possibly be bred out but not always. Sometimes, you think, if I just tried this one more thing maybe it would work this time. Sure, there are surprises and exceptions but usually bad traits will be hard to breed out. Anyway, I hope you get my point and, if you want to be serious about it, that you study and learn by other’s mistakes.

The way I hybridize is to picture both parents in my head, knowing by study and experience what the possibilities are, and visualize just what kinds of children to expect. Usually I’m not too far off. Sometimes I cross really unusual things just to see what happens and do get some surprises sometimes. Also, if you’re trying for a specific trait, you may be limited in what parents you have to work with. Say you’re trying for orange flowers. Until recently you only had 4 or 5 orangish begonias to play around with and all had very similiar looks and traits and all were hybrids of B. dichroa. You were pretty much stuck with using one of them even though they all have some bad traits and are harder to grow. The bad traits can be bred out eventually, but may take generations to acheive.

If you’re going to hybridize, (unless you’re doing it strictly for the practice), try to do something that’s different. Don’t cross B. ‘Hazel’s Front Porch’ (plain green leaf, dark pink flowers) with B. ‘Robinson’s Peach’ (plain green leaf, odd shade pink flowers) and expect that you’re going to get something really different. You just aren’t; you’ll get something similar to a hundred of the old varieties that we already have with plain green leaves. If you must use those to hybridize, cross them with a superba with spots or something so you get a little variety.

I usually cross a hybrid with a hybrid, or a hybrid with a specie but rarely cross two species because most of the seedlings from a specie to specie cross look alike. I crossed B. U032 with B. lubbersii and all of the seedlings(100) were almost identical and none exciting and I dumped the whole cross. With the other two types of crosses you get more variety because things can pop up from any of the grandparents. There are a lot of hidden traits that can show up that you didn’t know about, so it’s more exciting and your chances of getting something different increases. Give it a try! You might just find it thrilling to create something new.Most of you know already, but for those of you who don’t, begonias have the male and female parts contained in separate flowers. On nearly all begonias, first the boy flowers open in a cluster and as they start falling off then the girl flowers come out. I imagine this was mother natures way of preventing self fertilization. A typical male flower has two large petals and two smaller petals (actually tepals that look like petals) and in the center are the yellow stamens which hold the pollen. Most female flowers usually have five petals and yellow curly cue pistils in the center which are the parts of the female flower that receive the pollen. Behind the petals you can see the three-winged pod that is the ovaries of the flower and where the seed will form and mature. Now, as I said, these are the ways they usually look, there are some variations, extra petals and things, but, as a general rule, they match the descriptions.

Mechanics of how to hybridize: We’ve discussed different aspects of choosing parents for hybridizing, now we need to discuss the actual mechanics of how to hybridize.

With Begonias, especially hybrids, which parents you choose to cross with depends also on which ones you can find pollen on. Some hybrids either don’t produce pollen because they’re sterile or the flowers fall off without opening or the pollen just doesn’t mature before the flower falls off. It won’t take you too long to learn which ones never have pollen. There are also some which were crosses between two very unrelated types of begonias that don’t have complete flowers. Those won’t have pollen either, like B. ‘Question Mark’ that doesn’t have any anthers. Any true specie has to have pollen, that’s the only way it can reproduce itself in the wild. If yours doesn’t, then it’s a cultural problem and a change in something you’re doing like overwatering, humidity, etc., may get it to produce pollen, if it wasn’t.

The easiest way to test for pollen (the best time to check is early afternoon when the pollen is more likely to be ready because its warm and dry) is to take a mature male flower that’s fully open and hold it up to bright light and gently flick you fingernail across it. If there is pollen you should see a little puff of yellow dust flick out. If you have trouble seeing, try flicking the stamens across a piece of black paper and you should see the pollen on it.

For the female flowers I choose several flowers in the same cluster that have been open for a couple of days and are fully open, the petals may even be starting to curl back. I usually take three or more male flowers that I know have pollen off the father plant for the pollinating. On the mother plant I take the cluster that I’m going to pollinate and remove any male flowers (so it can’t self pollinate) even from other close clusters. On species it is wise to keep all male flowers removed in advance of crossing it because the wind can cause it to self pollinate. I also remove any immature female flowers from the cluster. They take away energy from the ones you’re pollinating and you won’t have to remember that there were some in that cluster you didn’t pollinate. To do the cross, take the male flower and gently bend the petals back, as a handle, to fully expose the anthers and gently brush it in the center of the female flower. As I said, I use three or more males and with these I brush across all the female flowers in the cluster just to make sure all get pollinated. To mark the cross (this is extremely important) I use a narrow strip of mailing or computer label with the cross written on it and bend it across the flower stem. Use a pencil or permanent pen to write the cross on it with so it won’t get washed off.

If your pollination was successful, in the next day or so the petals on the females will close and eventually drop off. If they don’t close by the second day, then reapply pollen to make sure it takes. The petals don’t always close on all varieties, so it may still have taken even if they don’t close. A sure sign is the ovaries start to grow fatter. This shows something is happening in there. It will take a month or so for the pods to ripen so be patient. When the flower stems dry up or shrivel, you can remove the pods whether they are dry or not. They won’t get any more sustenance when the stems have shriveled so you can’t hurt anything by taking them off.

Don’t take them off before this time though, they won’t have matured to their full potential. If you’re in doubt, then leave them on till they’re fully dry, but make sure you watch them and take them as soon as you see the pods start to split or you may lose all of your seed. I place the mature pods into small plastic film canisters or something similar, I don’t put a cover on because you need to make sure they get fully dry. I leave them for at least a week or more to be sure. ( One side note: if your pods fell off just when you thought they were almost ready you can try drying them. They usually don’t have good seed, but you may get lucky). Make sure you label the container with the cross to keep track of what that seed is.

After the seed is dry, I open the pods on a sheet of typing paper. To separate the good seed from the chaff, I tilt the paper slightly to roll the good seed off onto another piece of paper. The chaff and immature seed is left behind. If nothing rolls then it probably is all chaff and never fully matured. If you are in doubt, bring it to me at a meeting and I’ll check it for you. I would say about 70% of the pods I collect are good so that leaves 30% that aren’t for various reasons. I fold the cleaned seed into a small piece of paper and tape it closed, and write the cross on the outside with the date. Since I don’t plant seed until late fall, I just keep them in a coffee can or something until planting time. In the winter when I’m done with all the planting I’m going to do, I put the left over seed, into a tupper-ware container in the refrigerator. It will last a few years that way. I usually do a lot more crosses than I intend to plant because it’s always better to have more than you need. Not all of your crosses will come up either even if the seed did look good or there can be accidents, etc. Its just good to have a lot of extra seed to play with. Also, this is my personal opinion but I don’t think you should share hybrid seed with your friends, especially if you plan on growing it yourself because you and they might grow identical plants and give them different names, as I said earlier. Now, if you want to self pollinate some species for the seed fund or to share with friends, you can do that and it would be greatly appreciated. I hope this has helped any budding hybridizers or any of you who just want to get some seed to grow. Actually, growing the seed is covered on this site so follow the growing the seed link to get the rest, good luck.

Credits / references:
Brad Thompson | Brad’s Begonia World

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