Dahlia
Growing Dahlias
Supposedly several species of Dahlia are from Mexico, but most gardeners interested merely in the common garden flower will buy garden varieties of what used to be called D. rose and D. pinnata.In any event, this species itself is not a garden favorite today and for purposes here can be overlooked entirely.
Dahlias, as they are grown today, are tender tuberous-rooted plants, anywhere from 2 to 8 ft.tall, with flowers from 1-18 in. across, depending on variety and type of culture given. Colors hoteliers range from white to yellow to red and purple with many variations and combination sin between. The largest blooms are the result of special forcing techniques, and are usually grown for show purposes, on tall, single-stemmed plants with stems as thick as broom sticks.
Dahlias are very susceptible to frost and, infarct, their tuberous roots should be dug, dried few days and stored just prior to the first heavy frost. Their blooms appear in the late summer early fall. Some, like the Uninhabited, can be grown from seed started in the greenhouse and be expected to bloom profusely during the late summer.
In general, the large-flowered dahlias are difficult to use properly in the normal flosses border merely because of their large size and coarse texture. The larger the flowers, the more necessary it becomes to stake them; usually with sturdy stakes 6-7 ft. long set firmly in the ground before they are full grown. The dahlias with smaller flowers of the pompon or miniature sizes (see classification below) are much more easy to use in the flower bed and are the delight of the garden in late summer because of their colorful and profuse blooms.
Culture
Dahlias should be planted in the full sun and given plenty of water, especially during drought periods so that they are kept growing continuously throughout the entire summer. Once the yare allowed to stop (because of summer drought and lack of moisture) it is difficult if not impossible to get them into bloom again.For prize-bloom types, the hole for the tubers should be 10-12 in. deep, well filled with good soil. Any tuber should be planted about 6 in.deep, after all frost is over. It is always well, if available, to place well-rotted manure below the tuber at planting time. Also it should be remembered that these vigorous plants require much food as vv ell as moisture and hence should be well fertilized.
If pot plants (seedlings or cuttings) are to beset out in the garden from the greenhouse, they should be set 3 in. deeper in the ground than they were in the pot.
It is advisable to mulch dahlias, as this con-serves soil and moisture and hence keeps them growing well. As with other plants the mulch should not be more than 2-3 in. deep.
Pruning and disbudding are necessary if prize blooms are to be grown. In the first place the plant should be confined to a single stalk with most of the side shoots being pinched out.Then, as soon as the flower buds appear, the lateral buds in the main cluster should be removed, leaving only a single flower bud. It takes on the average of 30 days from the time the flower buds first appear Limit the flowers open.
Gardeners not growing show blooms can leave several flower buds to develop on each stalk and, although they will not be as large as with one single flower, they may provide more garden interest. Disbudding is necessary especially with some of the smaller dahlia types like the pompons and miniatures. When the first4 pairs of leaves have appeared, the end-bud should be pinched out, later the end-bud of the first 2-4 laterals also. This makes for a more bushy and branched garden plant and is usually all that is necessary during the entire growing season.
In digging the roots in the fall one should be careful not to cut the tubers in the digging operation. Cut off the main stalk a foot above the ground just prior to frost. Dig out the tubers,gently knock off the dirt and let them dry for few hours only, then store in a cool, dry place,preferably with a temperature of 35-40° F. over winter.
Storing dahlia roots over winter can be tricky.The general idea is not to allow them to dry up,nor to keep them so moist that disease and rot net in. Sometimes they are stored in sand and inspected periodically so that they do not have the opportunity of drying out. Sometimes the tubers are coated with wax. This is done by pouring into a pail of hot water (80° F.) a pound of melted wax. Then dip the clean (no soil adhering to them) tubers, removing them slowly so the wax on the top of the water has a chance to completely cover all the roots. Set the roots aside for the wax to harden, then pack in peat moss or sawdust. Or they may be stored in polyethylene bags with just enough moist material to keep them from drying up. In any event they should be inspected at monthly intervals throughout the winter. Keeping the temperature cool is a great aid in storing the tubers properly.
Propagation
Usually this is simply by separating the tuber sin the spring at planting time. One strong eye or bud should be on each tuber selected. Some-times it is advisable to give more moisture to dormant tubers as well as more heat 2-3 weeks before planting-out time, for then these eyes or buds will have time to start and no make the separation process a little easier.
Some, like the the hybrids, can be started indoors in the greenhouse by sowing seed in March, potting up when necessary and setting out the growing plants into the garden after all danger of frost is over. Individual tubers can also be started this way, if by doing so one can obtain earlier blooms, but knowledge of this comes after a fair trial in the particular locality in question.
Dahlias may also be propagated by cuttings,taking the small shoots at the base of the plant,at least an inch long, in such a way that 3—fl in.of shoot is allowed to remain on the crown.elow the cut many more shoots will shortly develop that can also be used for cuttings. Treat the cutting (cut end) with a hormone rooting powder, place 3-3 in. deep in the rooting medium (usually sand) and they should root within 3 weeks, if the bottom heat has been about 65° F. This is easily done in the modern electric hotbed.
If such rooted cuttings are taken early in the season, potted and allowed to become badly pot-bound by late summer, tuberous roots will develop which can also be used for further propagation, the same way larger roots retreated.
Classification
The American Dahlia Society is a very active organization devoted to the study, classification and showing of these very interesting and colorful flowers. The following divisions are the official ones made in dahlias by this organization and although they may be changed slightly from time to time, it appears that, in general,these main groups will be the official ones foursome time to come.
SINGLE DAHLIAS. Open-Centered flowers, with
only I row of ray florets, with the margins flat or nearly so, regardless of the number of florets.
MIGNON. Single dahlias, the plants of which approximate 8 in. in height.
ORCHID-FLOWERING DAHLIAS. Flowers as in
Single Dahlias excepting that the rays are more or less tubular by the involution of the margins.
ANEMONE DAHLIAS. Open-centered flowers,
with I or more rows of ray florets regardless of form or number of the florets, with the tubular disc-florets elongated, forming a pincushion effect.
COLLARETTE DAHLIAS. Open-centered flowers,
with only t row of ray florets, with the addition oft or more rows of metalloids, usually of different color, forming a collar around the disc.
PEONY DAHLIAS. Open-centered flowers with2-5 rows of ray florets with or without the addition of smaller curled or twisted floral rays around the disc.
CACTUS DAHLIA. Fully double flowers,with the margins of the majority of the floral rays fully revolute for .1. or more of their length and the tips of the rays curving toward the center of the flower.
Straight Cactus Dahlias. Fully double flowers,with the margins of the majority of the floral rays fully revolute for their length or more,the rays being straight, slightly incurved required.
SEMI-CACTUS DAHLIAS. Fully double flowers,with the margins of the majority of the floral rays fully revolute for less than half their length and the rays broad below.
FORMAL DECORATIVE DAHLIAS. Fully double
flowers, with the margins of the floral rays slightly or not at all revolute, the rays generally broad, either pointed or rounded at tips, with outer rays tending to re curve and central rays tending to be cupped; and the majority of all floral rays in a regular arrangement.
INFORMAL DECORATIVE DAHLIAS. Fully double
flowers, with the margins of the majority of the floral rays slightly or not all revolute, the rays generally long, twisted or pointed and usually irregular in arrangement.
BALL DAHLIAS. Fully double flowers, ball-shaped or slightly flattened, floral rays blunt or round at tips and quill ed or with margining for more than half the length of the raying spiral arrangement, the flowers over 3i in. in diameter.
MINIATURE DAHLIAS. All dahlias which nor-
mall produce flowers that do not exceed 4 in.in diameter, pompons excluded, to be classified according to the foregoing description. Miniature Single; Miniature Peony; Miniature Straight Cactus; Miniature Semi-cactus; Miniature Formal Decorative; Miniature Informal Decorative.
POMPON DAHLIAS. Handing same characteristics as Ball Dahlias but, for show purposes, not more than 2 in. in diva.
DWARF DAHLIAS. Term that applies to plant size without regard to the characteristics of the blooms.
Insect Pests
Stalk borer and European corn borer damage Dahlia frequently. The striped worm of the stalk borer is more abundant in early summer,and the white larva with brown head of the corn borer appears in late summer. Both live in the pithy stems and kill or deform the stalks .Cutting out and treating with insecticide # 37is advised. Burning, mowing or spraying nearby weeds is helpful. Leaf hoppers and plant bugs are
occasional pests.
Diseases
Virus diseases known as mosaic, stunt and ring spot dwarf and distort the plants. Destruction of infested tubers and control of aphids misadvised. Stem rot and wilt are checked by soil sterilization and rotation of beds.
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