The meeting in March was about breeding and growing Dahlias with a talk by Christina Angelucci who has only been growing these beautiful blooms for about 10 years.
She began by giving us a bit of background to the dahlia. Dahlias are indigenous to the mountainous regions of Mexico and Central America and were first documented by the Spanish as acoctili (their Mexican name) in 1525. The Aztecs farmed the tree Dahlia (which can grow 10m in a single season) and used their hollow stems as water pipes. Forty-two different species are found in the wild and many of these were cultivated as a source of food. The Aztecs also believed that Dahlias were a cure for epilepsy.
The first plants from Mexico arrived in 1787 to the Madrid Botanical Gardens and were named Dahlias in honour of Andreas Dahl, a Swedish botanist. In 1804, Lady Holland (an English hostess and wife of a politician) was given either seeds or more likely a slip of tuber which she sent back to England where they were grown on into flowering plants by her gardener.
These first dahlias grown outside of Madrid were single & multi-ray open centre flowers, but the horticulturalists at the time soon discovered that the Dahlia was a natural hybrid and when grown from seed, it would readily change its form and colour. They were highly prized and in the 1820s one tuber could cost as much as #100
Today we have a large range of Dahlia flower types: waterlily, peony, orchid, chrysanthemum, and anemone, which come in a variety of forms like the decorative (flat, broad petals), the cactus and semi-cactus types (rolled, pointed petals) and the ball forms (globular flowers) that have as their smallest relative the popular Pompon Dahlias. Almost every colour can be grown except for blue.
Christina’s Dahlia journey began when she purchased a couple of dozen tubers to see how she got on with them and then by 2019 she was growing about 800 different dahlias. She certainly has a passion for dahlias! She shared pictures of many of these lovely blooms and she picked out a few favourites:
Totally Tangerine, an anemone type which can flower as early as June,
Honka Pink, a star orchid type with an open centre, preferred by pollinators,
Classic Rosamunde, a peony type with bright pink flowers set off by very dark foliage,
Lady Darlene, a large decorative dahlia with golden yellow petals having a vivid magenta edge,
Not content with just growing dahlias, Christina thought it would be fun to start to hybridize her own. Apparently, dahlias are ‘octoploides’ which means that they have 8 sets of genes, therefore flowers can have a huge variety of colour and form and be produced from the hybridising of just 2 plants. She began by growing the wild form of Dahlia coccinea so that she could get a seed pod. (This is how the first hybridisers began to breed dahlias).
She sowed the seed from the first pod the following year and managed to produce 23 plants the year after which had been open pollinated her other dahlias. Once she had proved the concept, Christina began to hybridize her own dahlias using flowers grown from a packet of Dahlia ‘Bishop’s Children’.
We were shown how she crosses the dahlias using paintbrushes to collect the pollen on a warm day and transferring it from one flower to the next. Muslin bags over the pollinated flower then prevent any cross contamination from visiting bees. Christina’s aim is to produce open centered varieties of flowers to provide food for our rapidly declining pollinators. She is also interested in producing delicate dark foliage to set off the colours.
Obviously, with such a lot of Hybridisation, many hundreds of seeds are sown each year and so Christina showed us how she germinates her seeds using a stack of pieces of damp kitchen paper folded in half. She can accommodate 3 packets of seeds in 8 pieces of paper. Viable seed will germinate within 10 days and once sprouted are transferred to a cell tray.
The questions at the end produced some useful information:
- Dahlias thrive in sunny conditions.
- Christina always digs up her tubers to store over winter in crates of wood shavings.
- Any piece of tuber with an eye will grow on successfully.
- Tubers can get stale eventually and so it is better to take cuttings as they come into growth to reinvigorate the plant.
- Dahlias prefer to be grown in a loamy soil and to be fed regularly – Christina uses seaweed feed.
- Watch out for slugs using whichever is your preferred method.
- All dahlia flowers are edible, scatter their petals on salads for flavour, texture and colour.
Pauline Bartlett