December 2002

Culture Tips for ‘Dapper’ Dahlias By Lori May

‘Dapper’ dahlia is one of the newest dwarf series on themarket, with six colors. Dapper features small, semi-double, 2-inch blooms;dark green foliage; and a uniform habit. The Dapper colors are consistentacross varieties ? from Bronze through Deep Rose, Pink, Scarlet, Whiteand Yellow.

Dapper plants are early to flower and versatile in4-inch and larger pots, baskets, colorbowls, patio planters and window boxes. Dappers, available as both rooted andunrooted cuttings, work well in combination pots, as their dwarf habit andflower power really shine. This series also performs well in the landscapebecause of its sturdy, compact shape and nicely mounded, 8- to 10-inch habit.

Scheduling

Dapper is fast-cropping at 6-8 weeks from a rooted cuttingto a 4-inch pot. Use one cutting per 4- to 6-inch pot or 1-gallon container. Addan additional 2-4 weeks for finishing larger pots and gallons. If using Dapperdahlias in a basket, use at least three cuttings per 10-inch or five cuttingsper 12-inch basket.

Propagation

Clean and disinfect your propagation area thoroughly before cuttingsarrive. As with all vegetative material, quality is dependent on how quicklythe cuttings can be put into propagation.

Open the boxes upon arrival, and stick the cuttings as soonas possible. If the cuttings have to be held until the following morning, storethe opened boxes at a temperature of 42° F.

Rooting hormones containing 500-1,000 ppm IBA will aid inrooting. Be sure to shake off any excess hormone, as too much can cause damage.

Rooting time is 15-21 days with a bench temperature of68-72° F. Mist lightly for the first 4-6 days. It?s important toavoid over-misting, as keeping the foliage too wet can contribute to diseasepressure, especially Botrytis.

Growing On

Use a well-draining, soilless media with a pH of 5.8-6.2,and keep the media evenly moist. If the plants are kept too wet early, growthand flowering will be slowed. Do not allow to dry down to wilt, as this canhave an even bigger effect on the final quality of the crop.

Dahlias are moderate feeders, so fertilize at a constant rateof 200-250 ppm nitrogen. Alternate between 20-10-20 and 14-0-14. Keep an eye onyour ammonia levels, as excessive amounts will cause soft growth. Mostimportantly, dahlias are sensitive to high soluble salt levels, so maintain anEC as close to 1.0 as possible.

Maintain a night temperature of 62-65° F and a daytemperature of 68-72° F. Cooler temperatures (mid to lower 50s) willpromote tuber development and delay flowering; temperatures higher than 80°F can also delay flowering and cause bud abortion.

With regard to lighting, there are two critical factors forthe best-quality crop: Dahlias need over 2,000 foot-candles of light, as lowerlight levels can result in leggier plants with fewer buds; and dahlias need daylengthsover 12 hours for early flowering, as shorter days will promote tuberdevelopment instead of vegetative growth and bud set. Use night-interruptionlighting (minimum 10 foot-candles incandescent or 400 foot-candles HID) from 10p.m.-2 a.m. during short-day periods.

Dappers are bred to be compact and branching. They generallydo not require growth regulators. If necessary, B-Nine can be used at 1,500 ppm2-3 weeks after potting. Bonzi at 2-4 ppm has also been reported as effectiveon dahlias.

Pinching is not required, but it can improve branching ifdone 12-18 days after transplant. Keep in mind that in doing this, floweringwill be delayed at least 5-7 days.

The most common insects on dahlias are thrips, aphids,whiteflies and fungus gnats. Use labeled rates of insecticides for control.

Pythium, Rhizoctonia and Botrytis are the main dahliadiseases. Preventative applications of fungicides can be applied to avoid theseproblems. Culturally, avoid overhead watering, and maintain good air circulationto help prevent Botrytis infections. Allowing the media to dry slightly betweenwaterings will also help prevent root diseases.