Why aren't my Stocks double flowered?

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Must be Stocks week!  I had a strong complaint from a gardener that hardly any of her Stocks were double, they had no scent and they are dwarf!  Then I had a cut flower grower in the nursery wants to know could we supply him with those superior Double flowered stocks he had seen in 200mm pots?

Let's be fair, the potted stocks are relatively expensive hybrids and the plants grown at home from punnets were rather a old fashioned open pollinated variety. In both instances I had to say I have little to no control over the "Doubleness" of the flowers.  Interestingly we have grown 2 batches of Stocks in 200mm pots this season, both the same hybrid but the earlier batch was grown from older seed.  That first batch was predominantly single flowered, the second batch (available NOW) is 60-70% double. I think the single flowered plants tend to be more vigorous, so it might be we will have to use fresh seed for each sowing otherwise we get higher rates of singles.

Either way, the smell divine without being over powering. Stocks come from the genus Matthiola, named in honor of Piero Andrez Matthioli, 1500-1577. An Italian physician and botanist. An old common name is Gilliflower, they  are native to the Mediterranean and belong to the Brassicaceae family with Broccoli, Cauliflower and Alyssum. I used to avoid growing them because they were prone to Downey Mildew but the breeding has improved and so possibly has our culture and the mildew is rarely seen now.  Grow them in a sunny position and don't let them get too wet, otherwise they are actually an easy to grow flower. We find they perform best when planted mid-late Autumn to flower late Winter into Spring. The flowers don't last forever but they are very striking and the fragrance is delicious.