 |
The Gardener's Almanac |  |
||||
| Index | FAQ's | Links | Photos | Guest book | ||
| Dahlias |
The National Dahlia Society Classification;
n.b. Click on pictures for more pictures from same group.
Related Links
Basal cuttings Coldframe Compost Fertiliser Frost Fungicide Heating Plant out Soil preparation Watering
Group 1; Single-flowered Dahlias
Single dahlias have blooms with a single outer ring of florets which may overlap the centre forming a disc.
Group 2; Anemone-flowered Dahlias
Anemone-flowered dahlias have blooms with one or more outer rings of generally flattened ray florets surrounding a dense group of tubular florets, and showing no disc.
Group 3; Collerette Dahlias
Collerette dahlias have blooms with a single outer ring of generally flat ray florets, which may overlap, with a ring of small florets (the collar) the centre forming a disc.
Group 4; Waterlily Dahlias
Waterlily dahlias have fully double blooms characterised by broad and generally sparse ray florets, which are straight or slightly involute along their length giving the flower a shallow appearance.
The depth should be less than half the diameter of the bloom.
Group 5; Decorative Dahlias
Decorative dahlias have fully double blooms showing no disc.
The ray florets are generally broad and flat and may be involute for no more than 75% of their length (longitudinal axis) or slightly twisted, and usually bluntly pointed.
Group 6; Ball Dahlias
Ball dahlias have fully double blooms, ball shaped or slightly flattened.
The ray florets blunt or rounded at the tips, with margins spirally arranged and involute for at least 75% of the length of the florets.
Group 7; Pompon Dahlias
Pompon dahlias have fully double spherical blooms of miniature size, with florets involute for the whole of their length (longitudinal axis).
Group 8; Cactus Dahlias
Cactus dahlias have fully double blooms, the ray florets are usually pointed, the majority narrow and revolute for 50% or more of their length (longitudinal axis) and either straight or incurving.
Group 9; Semi-Cactus Dahlias
Semi-Cactus dahlias have fully double blooms the ray florets are usually pointed, and revolute for more than 25% of their length and less than 50% of their length (longitudinal axis), broad at base and either straight or incurving
Group 10; Miscellaneous Dahlias
This group is to cover for dahlias that do not fall into any of the foregoing groups, e.g. Orchid-flowered dahlias.
For exhibition purposes; some groups have been sub-divided into different sizes.
e.g. Waterlilys, Decoratives, Cactus,& Semi-Cactus are split as follows;
Giant-flowered - are usually over 254 mm (10") in diameter.
Large-flowered - are usually between 203 mm (8") and 254 mm (10") in diameter.
Medium-flowered - are usually between 152 mm (6") and 203 mm (8") in diameter
Small-flowered - are usually between 102 mm (4") and 152 mm (6") diameter
Miniature-flowered - should not exceed 102 mm. (4") in diameter.
Ball Dahlias;
Small flowered; - usually between 102 mm (4") and 152 mm (6") in diameter
Miniature flowered - usually between 52mm (2") and 102 mm (4") in diameter.
Pompons; should not exceed 52 mm (2") in diameter.
Dual Classification;
Some types of dahlias can have a dual classification.
These are varieties that are borderline in size or form, and as a result of this, they can exhibited in more than one group list.
Cultivation
Week 2-3; Check over dormant Dahlia tubers, remove any rotten parts, and dust with sulphur powder.
Week 5-6; Set saved tubers on the top of boxes/trays filled with a 50-50 mix of compost and sharp sand.
Water in with a mix of fungicide and water, mixed to manufactures instructions.
Place containers on a hot bed set to give a bottom heat of 18°C (65°F) and a surrounding air temperature of 10°C (50°F) to encourage basal growth for cuttings.
Normally, it takes around two to three weeks for basal growth to appear and a further four or five weeks to produce shoots that are suitable for cuttings.
Week 12 onwards; take 50-60mm long cuttings.
Remove bottom leaves and insert 30-40mm apart in a mixture of 50-50 (by volume) peat and grit sand (dipping cutting in rooting powder/liquid is optional)
Water cuttings in, with a fungicide solution.
Mist spray (daily) with a fungicide solution to prevent dehydration and damping off.
Week 15 onwards; depending upon available light, the cuttings should take around two to three weeks to root.
When the tip of the cutting looks a healthy shade of green suggesting that it has rooted, prick out into 70mm pots filled with potting compost.
Place pots in a well lit position but out of direct sunlight.
Week 18; Place cuttings in a cold frame to harden off.
If more stock is required lift tubers from trays and divide them into pieces ensuring that each piece has at least one 'eye' (growing point) on it.
Allow the wounds on the divisions to cauterise ( dry) before planting them out.
Week 19; If not already done prepare beds for planting out.
Check soil pH and adjust if required.
Week 22; When all fear of late frost has passed, remove the plants from their pots and plant out in pre-prepared beds and borders.
Set them 600mm (24”) apart supporting each with a 1200mm ( 4’ ) cane/stake.
To avoid any damage to the roots, position the supports in the hole prior to planting.
Tie the plant loosely to the support at regular intervals as the plant grows taller.
Pot up any surplus plants into 125mm (5") pots and grow on as 'pot tubers' in the cold frame. These will form the basis for the following years cuttings.
Week 25/27; Remove the growing tip of each plant to encourage bushier growth.
n.b. Dahlias require copious amounts of water during their growing season.
Week 26/28; Top dress the beds with a fertiliser such as Fish, Blood & Bone.
It can be advantageous at this time to mulch the beds with straw or spent mushroom compost to conserve moisture.
Week 30/32; Give plants a high potash feed to stiffen the stems and enhance the colour of the blooms.
Thin out the number of branches on each plant and remove secondary buds. This will give better quality long stemmed flowers.
Tie the remaining branches to sturdy stakes set three to a plant.
Week 35-36;If the plan is to exhibit it is beneficial to erect some form of canopy over the blooms to prevent them getting damaged by the weather.
Week 40 onwards; lift once the foliage has been blackened by the first frost, but if this does not happen, lift from late October to mid-November.
Remember to label named varieties.
Do this by pushing a length of plastic-coated wire through the hole in the plant label and tying it to, or through the tuber.
Drilling a hole through the base of the stem with a screwdriver or similar will enable any water lodged at the point where the base of the stem meets the tuber to drain away.
This will help to prevent moisture building up that could cause rot.
When the tubers are quite dry, remove the dried soil and trim off the thin water roots and any damaged parts of the tuber and store them in a cool frost free area until required.
Check periodically for signs of decay, remove any rot that may appear.
/Dec/Brian%20R%20(md).jpg)
/Ball%20&%20Poms/Willow%27s%20Violet%20(pom).JPG)
About this Site © The Gardener's Almanac 2005 Top of page