South American Plants - Dahlia

Name – The first dahlia tubers arrived in Europe at the end of the eighteenth century and were sent on merchant vessels to Madrid by the Spanish settlers in Mexico who sent back plants to their local churches as a form of religious ‘thanks’ for a safe voyage. At the Botanical Gardens in Madrid, where the tubers first arrive, the Abbe Cavanille named the genus ‘Dahlia’ for Andreas Dahl, a noted Swedish botanist and student of Carl Linnaeus.

Description – The dahlia has become a versatile hybrid, ranging from dwarf bedding plants that only reach twelve inches high, to giant specimens that reach taller than a man, and flowers can range in size from an inch to fourteen inches across. They are valuable late bloomers in the garden, because from the end of July to the earliest frosts, they offer large splashes of colour when so many other flowers are past their best – they come in shades of pink, lavender, red, yellow, white, bronze, purple, and there are many bicolours.

Origin - Dahlia roots need a sunny location in order to thrive and this means they must receive at least a half-day of sun - more is preferable if possible. To get the best from your plants, select a site that is away from trees, has the right amount of sun, and is sheltered from direct wind. Because dahlia tubers are surface feeders, they don’t send out a tap root which means the plants can be blown over by the wind or their roots can easily be ripped from the ground. This means staking the plants is essential. A good everyday garden soil is adequate in terms of plant nutrition, but good soil drainage is vital – if your soil holds surface water for more than several hours after heavy rain, you need to add compost or manure to improve the drainage. A key feature is that dahlia tubers need to be planted in warm soil, unlike tulips, so the rule of thumb is to plant them when you plant root vegetables such as carrots. This means spring should be well developed, and your plants shouldn’t reach the ground until you’re well into the longer and warmer days – in addition, you need to lift the tubers before the first frost and store them safely away from damp and cold, in a sand box in an insulated garage or shed, for preference.

For decoration - The wide range of dahlia shapes makes this flower suitable for a variety of uses – a florist’s tip is that as dahlias start to wilt from the back, gently pull these petals off for a fresh-looking, if smaller, flower.

South American Dahlia photograph by KaCey97007, used under a creative commons attribution licence

 

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