A hybridizing program

A hybridizing program for peonies

I’ve been hybridizing peonies since 2009, so with 15 years of trials and errors I think the time has come to give a short overview of where we’re heading. We’ve registered a few peonies which we think are worthwhile, you can easily find them in the cultivar registry of the American Peony Society, so we’re not going to mention them here. Rather I’d like to give those interested in new peonies a glimpse of our current work which may in due time result in still more registered cultivars. Given the time it takes to grow a seed into a flowering mature plant and the subsequent slow propagation which is typical for peonies, you’re looking at what may become available commercially in twenty years’ time. Coincidentally that’s about the time I hope to retire as well… Hybridizing peonies truly is a long term project with the labour, time and capital expenditures in the present and the benefits accruing only decades later. Fortunately the joy of seeing your first seedlings bloom arrives earlier after some 5-6 years already.

I could give a long description of all I’ve done in the years past, but it’s easier to simply start with the crosses made and seeds collected this year. If you’re interested in hybridizing yourself, you’re welcome to join the hybridizer’s corner where you can ask all questions related to this topic and where you can browse through older posts about peony hybridizing.

Today I went through my seeds collected this year to see which ones had sent out their first root and the table below summarizes it. The table is sorted from highest percentage germination rate to lowest (crosses with only 5 seeds or less are listed below it alphabetically as percentages don’t say much in those cases). The difference between a long and short root is at 5 cm length, which is more or less what is needed to be able to send up a first leaf in Spring (some extra time at higher temperatures may still move some with a short root to the other, better category). Have a look at it and then read further below.

We make some 400 – 500 crosses a year, mostly during the beginning of the blooming season. That’s about the maximum I can do as my main profession is still cut flower grower and that tends to take some time as well. The aim is not to have as many seeds as possible, but to have seeds from interesting parents, be they very fertile or otherwise. As you can see from the table, some crosses are far more successful than others. I had not written down the numbers of flowers pollinated per cross, but the ones with high numbers are mostly the result from seed pods with very high numbers per pod rather than a very high number of flowers pollinated. What you will also notice in the table is that the crosses with high seed counts are also by and large the ones with the highest germination rates. That is an interesting observation for someone who would like to give peony hybridizing a try. You can simply start with two very fertile cultivars which you cross, say Blushing Princess and Lemon Chiffon. That will result in a very large number of seeds of which a very large proportion will germinate. Given the beauty of the flower of those two cultivars and the good stems, you are more or less sure you’ll end up with a large double flowered peony with sturdy stems in some shade of yellow to pink. A rather satisfying project I would think…

Our main aims in hybridizing peonies are for plants with a good growing habit on the one hand and for plants with ‘different’ characteristics on the other hand. We don’t work with shrubby peonies, we do find them pretty, but there simply isn’t enough time to do that.

Hybridizing for plants with a good growing habit

A good growing habit in our opinion means that the plants will stand up straight without falling over when the weather is somewhat adverse. It also means that the plants should not be overly prone to diseases, that they should grow well, be rather floriferous and and always open well. That also means that ‘open buds’ should be avoided as is so often the case in many currently registered cultivars. A pretty flower is also important of course, but that in itself will surely not be sufficient here. Some good examples of better known peonies that fullfill these requirements are Old Faithful and Rozella (Reath, 1990). Remark that Old Faithful may have ‘open buds’ but unlike others those buds and flowers stand adverse weather well, thus we can forgive her for that. We have a few fertile seedlings that can hopefully give those characteristics to their offspring. In the table you’ll find many crosses with PVBM003 and BMBBY001.

PVBM003 is a selection from the cross Pink Vanguard (Seidl/Hollingsworth, 2005) x Buoy Master (Fawkner, 2011). It has leaflets down to the soil, very sturdy upright stems, dark green healthy foliage, closed buds and semi-double pink flowers which resemble Blushing Princess somewhat. It is very fertile both ways and early flowering. What’s more, here it has shown to be more tolerant to poor growing conditions and fungus infections. We’ve had this one for several years and through several propagation cycles a few dozen plants are available each year to make crosses with.

Another good selection is BMBBY001. This is a selection from Buoy Master x Vanilla Schnapp’s (Seidl/Bremer, 2013, formerly known as Bill’s Best Yellow, hence the BBY). It stands out from others thanks to its’ extremely sturdy stems mostly topped with very large closed buds and flowers of a single creamy white. This is a selection from a later date and due to some fungus infection we also lost some years of propagation, thus it is currently only a few plants. But the pollen is very fertile as you can see from the results in the table.

(Pastelegance (Seidl, 1989) x PVBM003) Semi-Double Yellow is another good and very fertile plant that is being used a lot. As is (Dreamtime x Mieke Bral (Hurtekant, 2020)) Thijs 001, which is an early white double, alas with open buds.

You’ll also notice that Old Faithful still features heavily. We also have a few seedlings from it that are truly standouts. (Old Faithful x Kathy’s Touch (Hollingsworth, 2009)) 002 Red for example is such a plant which is also very fertile.

Blushing Princess (Saunders/Reath/Rogers, 1991), Lemon Chiffon (Reath, 1981), Salmon Dream (Reath, 1979), Pastelegance and those other very fertile cultivars have been used in the past, but nowadays no longer play an important role in our hybridizing program. Dreamtime is an exception which we still use because we consider it to be the best one in this group.

Hybridizing for ‘different’ plants

Different plants are harder to describe than plants with a good growing habit. As already mentioned there are a few very fertile cultivars that will give you quick results. Everybody uses or has used those, us included, but it does lead to some inbreeding and ‘more of the same’. As we don’t really have a specific aim here, we try to work from a very wide gene pool and see what interesting things come from it. It is a far slower road to travel on with success spread far and long between.

Here it does help to build upon work by others and exchange plants, pollen and information with other hybridizers. So we have Andreas Maschke, an intersectional fertile backcross from Bartzella x Lemon Chiffon. We hope to end up with a cut flower that will hold in water but with leaflets, flowers and a fragrance more of tree peonies.

Another such interesting plant is OFF-4, which is from Old Faithful x Coral Charm (Wissing, 1964). The change of petal colours during bloom time is a trait we hope to introduce next to the ‘coral’ colour itself obviously. OFF-4 tends to give seeds both ways, but with an extremely low germination and survival rate, thus even though we’ve used it a lot, only a handful of seedlings are grown from it. The most interesting one is (OFF-4 x Grand Massive) Invictus, which is a pure white single with remarably glossy leathery foliage and tall sturdy stems. This plant is also much more fertile than OFF-4.

Yet another recent introduction into our hybridizing program is Flevo Star. This is a single white resulting from an open pollinated seed on Late Windflower (Saunders, 1940). It has inherited the fast growth rate and good health. We only have 1 plant of it as yet, so we haven’t had the opportunity to use it a lot, but we hope to do so more in the future.

Next to these interesting plants we also grow peony species for this purpose. This is a rather challenging road as it is different to find species (seeds or plants) which are true-to-name. The main issue however is that they are much more difficult to grow in general, except for a few species which have already been used a lot before. But as you can see in the table there are sometimes a few results. I’ve grown and used species from the beginning of my hybridizing program and have probably invested as much time in it as in my work with the other cultivars, but as yet I don’t really have much to show for it. Only a few hybrid plants have grown to maturity and so far none has been selected as being good enough for introduction. But we knew from the beginning that this was going to be a much slower process of course. Some second generation plants are being grown nowadays and we hope that inbetween those there will be more that are worthy of future registration and introduction.

So, that’s a bit what we are doing in this hybridizing program. Whilst it has taken us a lot of time to get where we are know, we’ve enjoyed the process so far and each year we are looking forward to again see some new seedlings bloom for the first time and some others grow into more mature magnificent plants.