Storage After Arrival Until Planting Time
Upon arrival, inspect the roots for any possible damage. Store the roots in the closed shipping container at 45-50° F up to 2-3 weeks.
Forcing Dahlia for Pot
The greenhouse requirements and general growth pattern of the Dahlia are quite similar to those of the Easter Lily. Dahlias begin to shoot
growth slowly and unevenly and will range from 1-2-3 or more shoots. DO NOT PERMIT MORE THAN 3 SHOOTS TO DEVELOP FROM THE CROWN.
After planting, water the medium thoroughly. Subsequently, for the initial 4-5 weeks keep the medium moist but not wet. After the shoots begin to
develop water should be applied directly to the medium. Avoid wetting the foliage whenever possible.Once the flowerbuds become visible, watering will
have to be more frequently and thoroughly. This is due to increased water requirements of the plant. On the date that A'Rest is to be applied as a
soil drench, the medium must be moist. Water the evening before and then apply the A'Rest the next morning.
Potting, Planting Medium, Spacing
Normally Dahlia are forced single in a 6" (15 cm) pot, either 3/4 or standard size pots can be used. Also either clay or plastic pots can be used but
plastic pots are preferred. Dahlia require a well drained, granulated medium. It should be sterile, have a pH of 6-7 and be low in soluble salts.
Because the application of A'Rest must be as a soil drench, the texture of the medium is critical. It should consist of equal parts of loamy soil,
a coarse aggregate, and peat. The organic matter should not be over 1/3 of mixture and the medium should not contain bark.
Light, Temperature & Ventilation in Greenhouse
Dahlia must be exposed to full sunlight throughout the greenhouse growing period. Dahlia should be forced at a minimum night temperature of 62-65° F.
Lower temperature will delay flowering. Day temperatures should be kept at 68-72° F. Higher temperatures if given for a prolonged period of time can
reduce the plant quality. To delay the development of the crop near the date of marketing, it is possible to lower the night temperature to 55° F,
conversely, the crop can be accelerated by forcing 70-75° F for a few days. Good ventilation is essential. Do not permit humidity to build up.
Dahlia require continuous fertilization beginning immediately after shoot growth becomes visible. A complete (NPK) fertilizer is required. A slow release
(14-14-14) fertilizer applied as a top-dress can be used. Also a weekly application of 200 ppmN of a 20-20-20 soluble fertilizer
The liquid feed can be used as a supplement to the slow release fertilization if needed. can be used.
Use of Ancymidol (A'Rest)
The only plant growth regulator approved for use in controlling the tuberous-rooted dahlia is ancymidol (A'Rest). For primary height control the
ancymidol must be applied as a soil drench no later than two weeks after planting. More precisely, it should be applied when the shoots are
approximately 1/4" (0.5 cm) long. At the time of application the planting medium must be moist! See variety list for use of A'Rest.
Each variety will produce a range of single, double or multiple shooted roots to develop the maximum flowers per pot at the time of marketing,
and to provide better shaped plants, it is necessary that all plants which are producing only a single strong shoots must be pinched. It appears that
the best stage of development to pinch out the terminal shoot is after the 3rd or 4th pair of leaves have unfolded. Dahlia normally form 2-4
pair of leaves. A pinch at this time will force 2-4 lateral breaks to produce more flowers.
All roots must be from cultivated stock, especially grown for pot culture. Do not use regular, uncultivated stock.
Planting, Medium, Watering & Fertilizer
Use a well drained soil pH 6-7 and a low soluble salt. Plant in full sun. Plant the crown slightly above the soil. Do not split roots prior to planting. Place
dahlias in rows 2 feet on center, while the rows should be 2-3 feet apart. Dahlias are a water loving plant. In dry conditions be sure to add water to
allow for proper growth. Continuous feeding is required, beginning at shoot emergence. Use a weekly application of 200 ppmN of a 20-20-20 or a topdress
application of a slow release 14-14-14 fertilizer. Cut when petals begin to loosen. Dahlias can be cut with or without foliage. Keep in cooler at 40-45° F.