On rhododendron hybridization

The previous pollinations of Weissenburg seem to have taken well as the pollinated flowers have started to shed petals quickly. I pollinated this one with two more hardy Finnish cultivars: Mikkeli (a smirnovii hybrid) and Kuutamo, a pale yellow-flowered bvtaureum hybrid soon to be released as 'Alli'. Another of my purchases this Spring is the famous Lem's Monarch. It is not going to be hardy here (hardiness estimated to only about -21C), but I bought it for crosses only. The reasons for choosing LM (apart from its excellent track record as a parent) are that it is said to be very large flowered (>10cm individual flowers in very large trusses) and that it is a known tetraploid. There are not too many confirmed tetraploid elepidotes easily available in Europe. Tetraploidy is desirable as for my interest to produce new azaleodendrons, i.e. hybrids of evergreen lepidotes and deciduous azaleas. I intend to pollinate LM with the tetraploid R. luteum and perhaps some tetraploid cultivars like Mandarin lights. I'm sure some have tried this combination and it may not be easy, but with some luck I believe a fertile azaleodendron could eventually be bred. R. luteum would incorporate two very desirable characteristics: intensive yellow colour so difficult to achieve by just crossbreeding elepidotes and, equally importantly, strong fragrance. LM started to open it's first flowers and for now I pollinated it with Mikkeli and Haaga. More next weekend. I have pollen of Cherry Cheesecake, an induced tetraploid version of Hachmann's Charmant. It is said to be relatively hardy, so I may try it on LM, too.

Other than that, I'm really looking forward to the first flowering ever of my own elepidote cross! It is September Flair X P.M.A. Tigerstedt, from 2008. I have 6 or 7 survising plant from this cross growing around the property, but so far only this individual has two fat flower buds. In the best case this will have yellow flowers. I'm prepared to pollinate this F1 plant with another F1 plant that I got as a gift from another amateur breeder in Finland: R. dicroanthum 'Böhmen' X bvt. So, it will be 'putative yellow' X 'putative yellow'. My first F2 cross ever!     

I did my first rhododendron crosses of the year on 11th May, Mother's day in Finland this year. The parent was Weissenburg, a double-flowered German hybrid that I ordered from Hachmann this Spring. I'm very excited about Weissenburg (R. 'Whitestone' X R. degronianum ssp. yakushimanum var. yakushimanum) as it is one of the very few double-flowered hardy elepidote hybrids. I've had Queen Anne's for several years and it's fantastic, though not fully hardy here. Weissenburg, with it's yaku blood, has very different, low growth habit. I pollinated Weissenburg with two hardy Finnish hybrids, Elviira and Haaga, for now. More next weekend. These double-flowered hybrids are very easy to work with as there is no danger of self pollination.    

The weather continues to be unusually mild. Snow is gone and snowdrops are blooming. I wandered around the property today to check my rhododendrons. The January cold spell with little snow cover damaged September Flair and Mozari (a xanthocodon hybrid) quite severy but otherwise the winter seems to have been easy on rhododendrons. I'm particularly happy that my own seedlings that I planted outside last summer seem to be in good shape. And one seedling from one of my first crosses ever, September Flair X P.M.A. Tigerstedt, has a flower bud on it! This seedling, however, is the one and only from my cross Queen Anne's X R. brachycarpum var tigerstedtii (called bvt from now on). It is very vigorous and has large leaves. I expect a lot from this youngster.

Rhododendron auriculatum is one of the rather few elepidote species with fragrant flowers. It is also one of the latest flowering of all rhododendrons. It starts growth very late and the current season's shoots harden very late. It is not hardy here and its late growth make it most suitable for protected woodland gardens also in milder climates. Always eager to try exotic plants I nevertheless bought a nice specimen from Rhododendron-Haven, Denmark several years ago. It was an interesting pot plant if somewhat sparse growing. I had the impression that R. auriculatum and similar tall-growing species flower only when old. To my great surpise my specimen formed fat flower buds already the next year, when only about 1m tall. In July 2011, which was record hot in Finland, the flowers opened. The flowers were luminous white, petals a bit wrinkly, and had a stong and pungent scent of cloves. The scent was totally different than the sweet, strawberry-like fragrance of R. fortunei. I pollinated my auriculatum with several different pollens, but unfortunately none produced seeds. Since I had now seen the flowering and we don't have a conservatory for longer-term maintenance of such tender plants I left the poor plant at the mercy of the elements outside, where it perished the next winter.

Despite the current unusually mild February weather (plus degrees and foggy, like cloudy days in April) the growing season is still months away. We're dreaming of building a conservatory where we could do some gardening even in midwinter. Until that happens we have to settle with the "cellar garden" where we overwinter rhododendron seedlings, tender plants, bare-rooted roses that arrived too late to be planted outside etc. I have set up two 36W fluorescent tubes with timer to help the evergreen plants survive the darkness. Rhododendron seedlings have done very well in these conditions. Roses tend to start growth too early and magnolias with their senditive root systems are always a challenge. These healty, lush seedlings are from my cross Queen Anne's x R. auriculatum and spending their second winter in the cellar. The leaves are hairy, a trait inherited from the pollen parent.

Uusimmat kommentit

22.08 | 19:53

Kiva lukea tarinan Tommy ruusun syntymästä . Ostin nyt tämän ruusun Oulun taimistolta ja toivottavasti se viihtyy täällä Pohjanmaallakin .

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21.06 | 20:08

Hei Raija, laitatko s-postia niin katsotaan pistokkaiden lähettämistä.

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21.06 | 20:07

Hei Hilkka, olen hukannut s-postisi. Laittaisitko viestiä jpkrvi(at)yahoo.co.uk.

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27.04 | 08:12

Hei Raija, ota yhteyttä s-postilla (jpkrvi(at)yahoo.co.uk) niin katsotaan, miten ja milloin voin toimittaa pistokkaan. T. Jukka

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