The Dahlia is a member of the aster or sunflower family (Asteraceae or Compositae) and is originally from Mexico. There the dahlias were grown for their edible, oblong, tuberous roots. These tuberous roots where boiled and eaten as vegetables. They taste like artichoke. Also the hollow stems of the Dahlia imperialis where used as water pipes.
The leaves can vary from species to species. Almost all cultivated dahlias are hybrids.
The most common cultivar groups are:
• Single (rich in nectar)
• semi cactus
• and various smaller groups
The Dahlia ‘Kelvin Floodlight’ is a member of the decorative dahlias and is also named dinner plate dahlia.
Dahlias are not very hardy, but if your winters are as mild as mine you can take the gamble and leave them in the ground. Here it does not get much colder than about -10 ºC (14 ºF) for a short period nowadays. This Dahlia ‘Kelvin Floodlight’ did not survive a frost period of -10 ºC (14 ºF) in the ground.
You can also dig up the tuberous roots just before frost sets in. Cut the stems to about 15 cm (6 inches) from the tuberous roots and store them in a dark, dry spot. You can roll them in some paper for example. Definitely do not put them in plastic because the tuberous roots will rot then. In February/March you can start the dahlias into growth indoors. You put the tuberous roots in a pot and place that in a warm environment (minimum 17 ºC (63 ºF)) in the light and keep the soil moist. If you are sure that the frosty days are over, you can plant them in their flowering site.
Plant the tuberous roots about 15 cm (6 inches) deep and about 50 cm (20 inches) apart. The bigger the dahlias grow, the further apart the tuberous roots should be planted. Dahlias that grow 60 cm (24 inches) or higher may need some support to prevent them tumbling over with strong winds or rain or their own weight. That is not necessary for the Dahlia ‘Kelvin Floodlight’. This dahlia has XXL flowers, which means that they can grow to about 30 centimeters (12 inches) wide. This dahlia grows up to about one meter (3 feet) but remains upright in the rain. Protection against strong winds is always recommended.
New growth in spring is a feast for snails and slugs so you have to stay on guard as long as the dahlia is still small. Earwigs can disfigure the blooms.
When the plant has developed a full third set of leaves, you can pinch out the center. This will produce a bushier plant with more blooms. Deadheading stimulates reflowering. Dahlias make excellent cut flowers and by cutting flowers for you bouquet, you stimulate the production of new flowers.
They prefer well-drained, humus-rich soil and a sunny spot with shelter against strong winds.
Attracts bees: no
Characteristic: newly emerging every year
Deer resistant: no
Exposure: sun/ part shade
Flower color: yellow
Flowering time: July – October
Foliage color: green
Fragrant flower: no
Hardiness: 23 ºF *(-5 ºC)
Height: 3 feet (1 m)
Soil: normal/ moist