Dahlias by Les and Viv Connell
Growing Instructions

Soil:

Dahlias thrive in well drained, sandy loam soil located in a sunny area. If you have a heavier soil, try adding sand or peatmoss to lighten it. Work in a 10-20-20 or 5-10-10 fertilizer or any kind of manure, two weeks before planting. Dahlias like a low nitrogen fertilizer. Fertilizers should not be placed directly in with the tubers when planting as this can cause burning. Use a 0-10-10 fertilizer such as "Mor-Blooms" after buds appear. Cutting out nitrogen during blooming will enhance the blooming season of your dahlias. Dahlias do not grow well in an acidic soil. Adding lime will sweeten your soil, lowering the acid level. Do not plant where beauty bark or bark dust has been placed as it causes your soil to have a high acid content and also slows down the warming of your soil. DO NOT add any weed killers to soil where or near your dahlias or it will kill them.

Planting:

Plant after the last frost. Planting depth should be between 4 to 6 inches and spacing about 18 to 24 inches apart. They can be as close as 12 inches but no closer. Lay tuber horizontally with the eye (growth bud) facing upward. Dahlias need support stakes which should be placed as you are planting the tubers. The eye of the tuber should be next to the stake. Avoid planting too close to trees or shrubs. Since plants may vary in height from dwarf bedders to 6' foot giants, set out tubers accordingly - the taller dahlias to the rear of the garden and the smaller varieties as border plants. DO NOT water the tubers after planting. There is enough moisture in the soil to maintain tubers until they are about six inches tall. Over wet soil will cause tubers to rot. If spring weather is extremely wet, delay planting until dryer weather conditions.

Watering:

Water once a week for established plants - more frequently if it's very hot or buds are forming. A thorough deep watering is better than frequent light sprinkling. Overhead watering is not recommended as it causes the flowers to become heavy and they will break. Also it causes white powdery mildew on your foilage Your dahlias may develop this mildew later in the season as the mornings are damper from dew. Dusting with a fungicide or sulfer powder can prevent it from appearing if used before the mildew has attacked your plants. If mildew has appeared use the fungicide as it will prevent it from spreading further but will not eradicate what is already there.

Pinching and Disbudding:

To create a compact bushy plant with more flowers, pinch out the center growing point when the dahlia plant is about a foot high. You will only need to do this once. For bigger blooms, better stems and quality form, pinch off the side buds at the end of each growing branch. Continue this disbudding throughout the growing season.

Winter Storage:

After your first heavy frost and your plants die back, dig your tuber clumps. A potato fork works best as it does not cause damage to tubers. Cut off stalks about 6 inches from the ground then dig a circle around the plant and lift clumps carefully out of the ground so the necks are not broken.
Wash well with sprayer on hose. You can divide tubers in the Fall or in the Spring. The eyes are easier to see in the spring, but the clumps can be tougher to cut then. Each tuber will need to have an eye (growth bud) which will appear where the tuber connects to the main stalk. Not all tubers on the clump will have an eye. Use a sharp knife (we use floral knives the size of pocket knives) to seperate tubers.
Allow tubers to dry in a protected area where they will not freeze or be exposed to direct sunlight - usually one day is sufficient. Store tubers in a medium, such as dampened sawdust, cedar wood shavings, or vermiculite. Wooden or cardboard boxes can be used to put medium in,but plastic bags are not recommended as tubers tend to rot from too much moisture. If you have to use plastic, make sure to poke holes in the bags so condensation can escape. The ideal temperature for storage is 40 degrees in a dry area.
Check your tubers several times during the winter. If you see signs of shriveling, you will need to redampen your medium. Treating with a fungicide or bleach water before storing will help prevent mold and mildew. You can dust dry tubers with a powder fungicide such as "Captan" or soak tubers in 1 gallon of water with 2 tablespoons of bleach for 5 to 10 minutes; then allowing tubers to dry as explained above. Everyone's conditions for storage are different so you may need to experiment before finding the system that works for you.
Remember tuber size does not affect plant growth. As long as the tuber has a healthy eye it will produce a plant. Tubers come in all sizes and shapes.
Tubers left in the ground over the winter need well drained soil and 5 inches of mulch for best results. If you have very cold winters with frosts that last longer then a few days, it is advised that you dig and store your tubers.