An Old Man’s Appetite For Growing Large Dahlias to Enrich Life
Forward by Dr. Leonard
Living in Minnesota presents a challenge to growing giant dinnerplate, decorative and fimbriated Dahlias. After many years of Dahlia growing experience, I offer suggestions that have resulted in many blue ribbons in state competitions with a number of growers. These flowers are most satisfying and complimentary to gardens and gardeners. Be patient and you will have an enjoyable and envied experience. Growing these beautiful flowers is a very satisfying past time. Good Luck!
Keep scrolling for Step by Step Instructions!
Indoor Pre-Starting of Dahlias
Prior to outdoor planting, one can start bulbs in a warm lighted environment, thus increasing the bloom time. Bulbs should be acquired only from reputable nurseries or from other Dahlia growers. Also, one can see if there is a local Dahlia Society in your area. Many growers like to share their excess bulbs.
To prestart Dahlias in trays or container pots, the soil to use is Miracle Grow or any starting soil. The light is supplied by fluorescent white lights or grow lights in lighting banks of one to three. Grow lights are not necessary.
The liquid growth fluid I use is Miracle Grow plant food at one tablespoon per gallon of water. Bulbs are covered with the starting soil and then the growth liquid is applied. Watering is carried out every 3-4 days and growth liquid is applied once every two weeks. Growth progresses rapidly.
The bulbs are started under the warm lighted environment in the beginning of April. The lights will need to be raised as the plants grow taller after several days, keeping them 6-12 inches above the bulbs to assure proper warmth. Plants grow up to 2 feet by the end of May and are ready to plant when frost is assured to be absent.
Using the same principles, one can also plant the bulbs indoors with proper lighting in 1-2 gallon pots, then transferred to the warm outdoor soil as above. Bulbs that are started indoors may also be divided after the plants mature for 6-8 weeks. Simply use a sharp knife and cut between the stalks, being careful not to cut into bulbs.
Always cut and throw away dry bulbs before starting the growth sequence. Remember, early starting of bulbs before ground planting assures large blooms. Dinnerplate and fimbriated bulbs are a great variety mix. Pre-growth with proper lighting and fertilizer are keys to successful flowers. Varieties are a personal preference, whether one wants dinnerplate, decorative, or fimbriated flowers.
Outdoor Planting of Dahlias
To start, the soil must be warm enough to sustain growth and thus guard against freezing. The soil temperature should be at least 60 degrees Fahrenheit. This temperature usually occurs around the end of May in Minnesota. One must cover plants with a light cover if frost is speculated overnight.
Once mature growth occurs under the warm lighted area, the plants are moved with their growth soil, and placed immediately in the ground. They also can be potted in gallon size pots and weather outside for a one or two weeks before ground planting, if desired. Plants are then accustomed to their outdoor environment. That is my preference.
Optimal Dahlia Growing Environment
Dahlias need at least 6-8 hours of direct sunlight for best growth. The outside planting area must be well prepared. If you have them, add a handful of composted leaves to the bottom of a one-foot deep hole in a well-drained area. Holes should be at least 4 feet apart from one another. Then, add a couple scoops of Miracle Grow starting soil before placing the pre-started Dahlia plants in the hole. Fill any remaining areas in the hole with good soil or Miracle Grow starting soil, pat down and water immediately.
Dahlia plants will need watering once per week, and Miracle Grow plant food given every other week. The Dahlias will need to be supported with 8-foot tall garden stakes that are sunk deep into the ground to support the weight of the growing plants. The Dahlia plant is tied with ½ inch plastic gardening tape. Blooms will begin within 2 months.
When watering, water only at the base of the plant. This will decrease the risk of hosting aphids or plant lice. Standard pesticide solutions can be used if bugs are identified.
To assure the largest flowers possible, smaller flower buds should be removed after the first bloom. This step is important. If you desire delayed blooms for competitive showing, or want to create the largest flowers, the plant top may be cut. When growing Dahlias for competitive showing, it is important to understand that the largest blooms will occur when the smaller collateral buds are removed. Also, plant food may be changed to increased phosphorus concentration once blooming begins (Miracle Grow Boost).
At the end of the season, plants are removed and bulbs should be taken from the ground and washed and dried. They can be stored in a cool area (40-60 degrees) in premium peat moss in a dark protected environment. Bulbs are rarely lost using this method. Do not store in plastic.
When plants are removed from the garden at the end of the growing season, be sure to mark the bulbs with a plant tag indicating their color and size for next year’s placement.
In the spring, usually around the beginning of April, bulbs are removed from the peat moss and planted as previously described. Any soft bulbs should be removed and stalks over six inches cut back.