Hybridising Elatum Delphiniums

Graham Austin, from RHS Chelsea Gold Medallists Home Farm Plants, runs through the process for hybridising Elatum Delphiniums to create stunning new varieties. - 24 May 2024

Over many years Home Farm Plants has built up a collection of over 100 named Elatum Delphinium cultivars.  When we first started the numbers collected rose steadily. There were a handful of nurseries that had small to modest collections and after one telephone call, plants were ordered and they arrived by post or we collected them; what an easy way to increase your collection. But 50 – 60 cultivars later it became clear that other cultivars were going to be harder to find.  Many other cultivars were around but they were not available commercially in nurseries.  This is when plant societies come into their own.  As a member of the Delphinium Society I began to get more involved and got to know many of the amateur breeders of these stunning plants. 

It soon became clear that these people not only had plants to look nice in their gardens but also for hybridising to produce new and improved delphiniums.  Their attention to detail was unbelievable but also ruthless as only perfect delphiniums in their breeding program were kept and any with slight faults were discarded.  The only problem was they would breed a new delphinium, name and register it, then go on to the next one without ever making it commercially available.  Luckily many of the breeders were only too happy to give or swap plants and our list began to grow making many long forgotten delphiniums commercially available again. 

As far as we are aware, some of the cultivars we had literally saved from extinction (by taking cuttings of the few plants left and producing more plants). There are now a number of large collections that have built up, including a National Collection, which is great because it now means cultivars are at least safe.

Undoubtedly there are still old cultivars to be found hidden in someone’s garden, hopefully with a label to help with identification, but the future of cutting raised delphiniums is a great cause for concern.

In the 20 years between 1919 and 1939 over 100 breeders registered and named an average of 61 plants a year.  Going forward to 2014, 6 new cultivars were registered but in 2021 and 2022 not a single delphinium was registered.  A slight improvement was seen in 2023, including a delphinium bred by us (Rebecca, named after our daughter).  Only a handful of amateur breeders remain and we believe we are the only commercial nursery breeding cutting raised delphiniums.  This is something that as a nursery we are going to concentrate more on.  If new delphiniums are not produced where will the heritage delphiniums of the future come from?

'Rebecca'

So what do you look for when hybridising delphiniums?  Firstly colour; a dark blue, clearer white or maybe a new colour break. What’s important to realise when hybridising is colour does not work like an artist’s pallette, so blue and creamy yellow will not produce green.  Look closely at your delphiniums (very closely and you may see a slight hint of another colour, say turquoise,) then find another cultivar with a hint of the same colour and cross them.  A couple of offspring may have some more of that colour, so cross them and eventually the colour will become more prominent.  It’s not just colour we look for as good form is important.  Florets should be neat and symmetrical and flat so as not to be affected by the weather.  The eye in the centre should be big and strong.  Height is a factor too; dwarf cultivars are always popular.  Flowering time is also important.  Austin’s Dawn Chorus, for example, which was bred by us, flowers very early and is flowering by the middle/end of May therefore prolonging the delphinium flowering season.

'Austin's Dawn Chorus'

The important thing is keep a record of your outcomes (good or bad!) Anyone can register and name a delphinium. If you fancy a go come and see me at a fair and if time allows I will show you how and what to do. For more information on how to grow and look after Delphiniums, please see my earlier article 'Desirable Delphiniums'.

RHS Chelsea Gold Medallists Graham and Nina Austin own Home Farm Plants, and specialize in Elatum Delphiniums and other perennials. 

Article and all photos copyright the author. 

Website: www.homefarmplants.com