Dazzling Dahlias at HOFS

Nick Dobson's talk to Hadleigh Gardening Association 19th July 2018

Dahlia Imperialis
Shu Suehiro - Own work CC BY 3.0
National Dahlia collection
National Dahlia collection
National Dahlia collection
National Dahlia collection

Originally cultivated by the Aztecs in Mexico, the Dahlia is a member of the Asteraceae family. Dahlia imperialis grows up to 10 metres and is native to Mexico and Central American uplands.  The flower-heads are 75-150mm across, lavender or mauvish-pink in colour.  The long canes, Nick told us, could be used by hunters to carry water.  

D. pinnata and D. coccinea were two of the three sent from Mexico to a Spanish botanist, Antonio José Cavanilles in Madrid at the end of the 18th century.
From these have come 57,000 named varieties.   Having more chromosomes than other plants allows a wide range of breeding from a limited gene pool.  
They are named after Anders (Andreas) Dahl  1751 – 1789,  a leading Swedish botanist and  student of Linnaeus.  

The first double flowering dahlia was produced in Belgium in 1805. Nick Dobson showed a steady pictorial succession of  classes of dahlia blooms;  including waterlily,   cactus, anemone, ball,  pompon and so on as shown at the side of this article, {© National Dahlia 2017.}

We got several hot tips, including the “go-to” supplier;    key requirements for successful dahlia growing, propagation and over-winter storage.  Importantly, we also heard a low cost and safe cure for mildewed leaves, i.e. 2 teaspoons of baking soda in 1 pt of water sprayed direct onto the leaves.

The HGA was recognised by the presenter as unusually healthy in number and enthusiasm;  and after the tea break, the appreciative audience went on to ask searching and far-ranging questions of our expert speaker.  An excellent time was had by all.

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