You can select the soil to suit the requirements of your Dahlias and the mobility of containers allows optimum light. Steer away from using garden soil in the Dahlia containers. Straight garden soil will hold too much water and drown the roots during wet weather but will compact and smother the roots during dry spells. Light, soil-less mixes are best because they do not compact and the high peat moss content helps maintain an optimum moisture level without becoming waterlogged. Pests such as slugs and snails are effectively avoided and containers remain virtually weed-free all season.
Correct moisture control is critical to successful Patio Dahlias. All containers must be checked frequently. A soft spray applied slowly is the best way to moisten the entire pot. Let the water drain right through the container until you see it run out the drainage hole at the bottom. If the container you are planting does not have holes add a two-inch layer of gravel to the bottom so that excess water has somewhere to go.
Plants need food as well as water to grow and thrive. It is therefore important to feed your Dahlias. Your Patio Dahlias should be fertilized with a water-soluble fertilizer. Also turn the pots periodically so that the Dahlias receive light evenly on all sides.
Since Dahlias in containers serve as focal points in most gardens it is essential to keep them looking their best. This can be achieved by removing spent flowers (deadheading) and by cutting or breaking off the tips of long shoots (pinching). By doing this you will be rewarded with thick, healthy growth and continuous colour.