Setting Hybridizing Goals and Selecting Parent Plants
Setting goals and selecting appropriate parent plants are important first steps in hybridizing Hostas.
By Joshua Spece
Last revised January 22, 2008
Setting Hybridizing Goals
Setting goals is the driving force for many of life's tasks and hybridizing Hostas is no different. If you don't know where you want to end up, how will you know where to begin?
Your hybridizing goals don't have to be extremely detailed. Do you like miniature Hostas? Then concentrate on developing miniature plants. If you love large gold Hostas, don't waste your time working with small blue plants. The main idea is to bring a little focus to your efforts.
If you do have a clear vision or detailed goal of the Hosta you want to create, so much the better. The more detailed your goal, the more direct the path will be that leads you there. You only have a certain amount of space, energy, and time to work with. Having goals will help you make the most of your resources.
Selecting Parent Plants
Hybridizing Hostas is not a short term project. You will probably not end up with a perfect "finished product" in just one step. Reaching your goal will likely involve several generations, but each cross will get you one step closer to achieving your goal.
With a goal sketched out in your mind, carefully decide what Hostas you can use as parents to reach that goal. Look at the Hostas you have to work with and choose two that have the characteristics you want to see in your hybrid. If your goal is to develop a superior gold leafed Hosta with red petioles, you should choose the best gold cultivar and the best red petioled cultivar to cross pollinate.
This is where things can get tricky. In a perfect garden, we would be able to cross pollinate any two Hostas we like. It's not that simple, though. Some Hostas are almost completely sterile.
Hosta 'Krossa Regal' is one sterile cultivar. Hosta fertility is not carved in stone, though, and rarely a normally sterile plant may produce viable seed. This is apparently the case here, because there are two registered hybrids of 'Krossa Regal'. Not a sign of good fertility, considering that 'Krossa Regal' has been around since 1980.
Sports will almost always have similar fertility as their parent. For example, all sports of Hosta 'Krossa Regal' are also sterile.
To complicate things further, some Hostas may set viable seed, but the pollen will not be viable. This can work the other way, too, and a Hostas can produce viable pollen, but will not set seed.
Fertility is not a black and white issue, though, and most Hostas fall somewhere between being completely fertile and completely sterile. Many plants will set pods under optimal conditions. Plant compatibility is also an issue. One Hosta may set seed when pollinated by one plant, but not another.
Determining what Hosta cultivars are fertile in what ways and in what combinations requires a little observation and a lot of trial and error. A good place to start is to look up a plant in the American Hosta Society Registrar Database and scroll down to the "seed information" section. This only applies to registered cultivars, though, and the data is sometimes missing or not even correct.
Hosta Bloom Period
Streaked Hosta Bloom Time Line
Jeff Moore has compiled this chart of bloom periods for a large variety of streaked Hostas. Data is from his zone 5, Wisconsin garden as well as other sources. This chart will be expanded and updated as new data is collected.
Download: Streaked Hosta Bloom Time Line (pdf - 23 kb)
The normal bloom period of the two plants you've chosen to cross pollinate can also be an obstacle. Every Hosta cultivar has a specific period of time that it blooms, determined by the plant's parentage. Hosta sieboldiana is the earliest bloomer, beginning in late spring, and the flowers of Hosta 'Tardiflora' are often greeted by frost in the far northern United States.
Many hybridizers are content to hybridize using plants whose bloom periods naturally coincide. There is nothing wrong with that! However, the most interesting hybrids result from crosses involving plants with completely different characteristics. Compared to early blooming cultivars, the late blooming Hostas have been utilized to a much lesser degree. Many uncharted waters are left to explore, if you are willing to go to a little extra effort to work with these Hostas.
Forcing Hostas to Bloom Out of Season
There are two different techniques you can use to cross pollinate plants with different bloom periods. The first is to manipulate the natural bloom period to coincide with the other plant you want to use. The easiest way to achieve this is to force a later blooming Hosta to bloom early. You can pot the late bloomer and sink pot and all into the ground for the winter. In late winter, bring the potted Hosta indoors and keep it under lights or in a sunny window until spring. The forced plant will bloom earlier in the season, since it got a head start indoors.
Forcing Hostas is not without risk. It can be stressful on the Hosta to have an abnormally long growing season. Carrying potted Hostas through the winter can also be very risky. I would suggest only potting a portion of the plant you want to force. That way you won't lose the entire plant if something happens to the potted division.
Forcing late blooming Hostas does have the added benefit of giving seeds plenty of time to mature. One reason late bloomers are not used more often is because the seeds often don't have time to properly mature before frost arrives. This is mainly a concern for hybridizers in northern climates.
See the section on Collecting and Storing Pollen for other ways of crossing Hostas with different bloom periods.
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