Photo Credit: Mark Twyning (Marktee1) at en.wikipedia, CC BY-SA 3.0

Common Name Dahlia  
Genus  Dahlia
Species Dahlia Pinnata 
Family Asteraceae
Life Cycle  Tender tuberous herbaceous perennial, can be grown as an annual. 
Tray Size   50
Plug Care Harden off before planting out. Do not allow plugs to  become rootbound - plant soon after receiving or pot up  into larger cells. Keep soil evenly moist - avoid drought and oversaturation. 
Netting / Staking Dahlias can grow quite large and benefit from staking. For small numbers of plants, individual staking will suffice. For rows of plants, utilize T-posts and heavy duty twine to stake the entire row. Some growers have found success using the Florida weave method. 
Temperature Range Extremely frost sensitive at all stages - best transplanted after soil has warmed in the spring and nights stay above 55F. 
Spacing 12-18" between plants, 2-3' between rows. The tighter they are planted, the less airflow between plants and therefore greater risk of fungal issues. 
Soil Preference

Fertile, loose, well draining soil of neutral pH. Dahlias  benefit from soil amended with composts and granular  fertilizer, or a light feed with irrigation every two weeks.  Heavy, saturated soil can initiate root rot. 

Day Length Dahlias are facultative short day plants. This means the plants will bulk up and be mostly vegetative during the  long days of early summer and budding will be initiated  as the days shorten. They require full sun conditions to thrive.
Pinching Pinch one time, when the plants reach approximately 12 inches in height. Remove the main shoot down to the 2nd or 3rd set of leaves to initiate the development of side shoots. This will delay flowering by a couple of weeks but the plants will be much more floriferous later in the season. 
When to Plant Spring, after the danger of frost has passed and the  temperature is expected to stay above 55F.
Harvesting Expect to harvest the first flowers approximately 90 days from transplant. Dahlia buds do not continue to open after harvesting and the flowers in general do not have the longest vase life. Cut when the flowers are approximately 3/4 of the way open. Cut deeply for a long stem, do not be afraid to remove 2 or 3 leaf nodes with each stem. This provides the highest quality cut stems and encourages the plant to continue branching near the base. 
Post Harvest Care Cut early in the day before the temperature climbs.  Plunge cut stems immediately into cool water. Keep in a  cooler until ready to sell. Vase life is highly dependent on variety - here at Farmer Bailey we try to source high  quality cut flower varieties for the longest vase life  possible. 
Diseases / Insects

Dahlia mosaic virus and crown gall are two highly  infectious diseases that are currently common in dahlia  collections across the world. Our plants have been  screened and cleaned of these diseases through the  meticulous process of tissue culture.   

Powdery mildew and botrytis (grey mold) may be observed during extended periods of cool wet weather, or late in the season when powdery mildew runs rampant. Increased airflow between plants helps prevent or slow the spread of fungal diseases, as well as drip irrigation to avoid wetting the foliage.

Thrips, Japanese beetles, tarnished plant bugs,  cucumber beetles, earwigs and slugs are just a few of the many insects that feed on dahlia plants and flowers. 

Bailey's Notes

Dahlias grown from cuttings do not always produce a  tuber in the fall - sometimes all of the energy goes into  flower production.

To avoid the labor and costs of digging and dividing  dahlia tubers every year, consider growing dahlias as  annuals - the price per plant is much cheaper when  purchased as plugs compared to tubers. Our plugs are  guaranteed virus and bacteria free, which is always a risk with purchasing tubers from untested stock.   


Fundamentals of Growing Dahlias