Types of Dahlia Flowers – Dahlia Varieties
To the novice dahlia grower, the classification of dahliamay seem rather confusing at first. But basically dahlia varieties are divided into main groups according to the shape and formation of the flower. The varieties in these groups are then placed in various sections of the group according to the size of their flowers. As an example let us take the largest group, the Decorative dahlias. This contains the typical dahlia varieties with fully double flowers which have broad, flat, well-formed ray florets. This group is divided into giant-flowered, large-flowered, medium-flowered, small-flowered and miniature-flowered sections.
Another large group contains the Cactus dahlias with fully double blooms but with narrower, more spiky ray florets than the decoratives. This also has giant-flowered, large-flowered, medium-flowered, small-flowered and miniature-flowered sections. Then we have the Semi-cactus dahlias, which again have fully double blooms, but the ray florets are slightly broader than the true cactus dahlia and narrower than the decoratives. This group has the same sectional divisions as the two types just referred to. A group of really delightful varieties is that which contains the Ball dahlia flowers which have fully double flowers, either ball-shaped or slightly flattened. This group is divided into only two sections, namely the ball and the miniature ball dahlias.
The Single-flowered group is not divided into sections, and contains those varieties which have a single outer ring of florets which may overlap, the centre forming a disc. Most varieties in this group are suitable for bedding as they are dwarf growers. Anemone-flowered dahlias have one or more outer rings of generally flattened ray florets, the centre of the flower being made up of a dense group of tubular florets, and showing no disc. Again, this group is not divided into sections. The Collerette dahlias, which also are not split into sections, have a single outer ring of generally flat ray florets, with a ring of small florets (the collar), the centre forming a disc. Peony-flowered dahlia varieties have blooms with two or more rings of generally flattened ray florets, the centre being formed into a disc. There are no sections in this group, nor are there in the case of Pompon dahlias. These last are charming varieties with blooms similar to those of the ball dahlias, but more globular and much smaller in size.
Although the Dwarf Bedding dahlia varieties are usually listed separately in dahlia catalogues, they do have various types of flower formation, such as cactus, decorative, single and so on, and are, there-fore, correctly placed in the appropriate groups which I have mentioned above. They are grouped on their own in catalogues simply for ease of selection.
The Best Types of Dahlia Flowers for Garden Display
The choice of types of dahlia flowers for garden display is purely a matter of personal appeal, but I would not grow the Giant-flowered and Large-flowered decoratives, cactus and semi-cactus varieties, as the flowers are far too large for normal garden display. They are all right for those people who grow for exhibition, but not for general garden use. All the smaller-flowered varieties in these groups, and the other groups Which have smaller flowers, are the ones I would use. These are also more suitable for use in flower arrangements.
If your garden is exposed and windy, I would certainly advise growing the less tall dahlia varieties. Those that grow tall, for example, over 4 ft. in height, will suffer badly from wind damage, and this makes extra work in staking and tying (I think that all these sorts of jobs need keeping down to a minimum)
When planting dahlias for garden display it is usual to group them in separate varieties rather than mix, say, half a dozen different sorts together. If you are putting them among herbaceous border plants then I think that one plant here and there in the odd space should be sufficient. If they are being planted in beds or borders of their own, then three to five plants of each variety is really the minimum number for any one group, in order to produce an effective display. An important point when growing plants for a display is to remove the dead flower heads regularly, as this will encourage the plants to keep up a continuous show of blooms. Bedding dahlia varieties can, of course, be mass-planted in their own beds, or mixed with other summer bedding plants such as the silver-leaved Centaurea gymnocarpa,Cineraria maritima (Senecio cineraria) and Pyrethrum ptarmicae-florum, or salvias, ageratum and verbena. There are many colour combinations which can be planned, but this must be left to the imagination and artistic skill of the gardener.
I usually plant a row of dahlias across thespecially for cutting, as this enables me to cut as many flowers as I like without interfering with the garden display.