Episode 136 - Show Notes & Advice

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episode 136 | show notes & advice

episode description

In today’s episode, Sarah chats with Head Gardener at Perch Hill, Josie Lewis, all about their recent trip to the dahlia fields in Holland. From successful breeding programmes to the newest and most interesting dahlias, discover what star qualities Josie and Sarah look for in prospective varieties for the range. 

In this episode, discover

  • Updates from the Perch Hill dahlia trials
  • Highlights from their recent trip to Holland 
  • The science behind dahlia breeding

links and references

Episode 136 advice sheet

A trip to Holland (1:44)

Sarah and the team recently took a trip to Holland to hunt for brand-new, exciting, and beautiful dahlias. 

Josie explains that the breeders collect seeds from a trial garden, which are then grown on to become seedlings. The seedlings are then grown on for another two years, over which time the breeders will look to see if the adult dahlia plant will develop strong tubers. The most healthy and productive dahlias can produce up to 400 tubers and if the growers don’t consider a dahlia to be productive enough, they can reject them.

Of the six dahlias selected for breeding from last year’s Holland visit, five came good. One in particular didn’t form any tubers, and unfortunately, didn’t make the grade. The five successful varieties where a combination of single, collerette, and anemone flowered varieties, which are excellent for pollinators. 

Update from the dahlia fields (12:00)

Sarah says the trial fields are like visiting a sweet shop for those who adore colour and dahlias. Each row boasts variety and diversity, with no two plants the same. 

The brand-new and incredibly vibrant Dahlia ‘Octopus Sparkle’ really caught Sarah’s eye. It literally looks like an octopus with its legs hanging down, with its body sparkling with masses of pollen-rich nectaries. Josie likens this variety to Dhalia ‘Honka Fragile’ for its interesting, quilled petals that make a real statement.

Perch Hill Dahlia trials (12:57)

A lot of dahlia seedlings Josie is trialling have recently begun to open, and every day she is met with new and exciting results. From striking anemone varieties to brightly coloured styles, Josie looks for early flowering dahlias with standout qualities. 

The crossbreeding process (14:35)

  • Choose two seed parents that you think might cross well. 
  • Next, place an organza bag (that you would normally keep jewellery in) over the bud and draw the strings tight. This will stop the bees getting in and pollinating and will let enough light through for the flower to bloom.
  • The next step is about tapping the pollen from another variety onto your chosen dahlia. You can do this with a paintbrush for accuracy. It’s been suggested that three days in a row produces good results. 
  • It’s important to identify the stigma, which Josie says can be found through removing some of the petals if it’s not quite as obvious. 
  • Once the pollination process is complete, place the organza bag back over the flower to prevent additional bees visiting, and let it mature. It’s important to try this method in dry weather to give the dahlia the best chance possible. You don’t want the seed head to become soggy either. 
  • Six weeks later and the seedhead will mature. The flower might look a little bit brown and crispy, which should give you a clear indication that the seeds are ready. 
  • Look for thick black seeds, the internet will be able to help you to identify viable and nonviable seeds. This can be done by hand – you won’t need tweezers to remove the seeds. Store the seeds back in the organza bag over winter.
  • Sow the seeds in mid-March and wait to see the results!