The blue delphinium is a beautiful perennial flowering plant that belongs to the buttercup family. Its name originates from ancient Greek and is so named because the flower was considered to be similar in shape to a dolphin. It is also referred to as a Larkspur, a name originating from Tudor England. In contrast to its beauty, all parts of the plant are highly poisonous if ingested.
Blue Delphinium Varieties
Delphiniums bloom in various colors from white, to pink and blue and have either tall spires covered in flowers or shorter and bushier stalks depending on the species. Some of the more popular varieties of blue Delphiniums include the “Blue Dawn” with pale-blue flowers or the “Blue Nile”, whose flowers boast a much more intense blue.
Reasons Bloom Color Changes Occur
Delphiniums can bloom one color on their first flowering and a completely different shade the following year. The main reason this color change occurs comes from cold damage to the plant’s roots as well as a change in the PH of the soil. Severe cold damage affects the genetic makeup of the plant as it tries to adapt to different conditions.
Blue Delphiniums require soil that has a higher acidity content which preserves the beautiful blue color of their blooms. As soon as the PH of the soil changes to increased alkalinity, the new blooms will be of a different color.
Maintaining Soil Acidity
In order to preserve the blue color of delphinium blooms, the soil’s PH level must be kept relatively low and the plant must have access to aluminum. A solution of 1/2 ounce of aluminum sulfate in one gallon of water applied to the area around the plant will solve this and lower the PH. This solution must be used cautiously as too much can lead to root damage. The plants must be watered well before application.
Another option to reduce the soil’s PH is to add organic matter such as coffee grounds, fruit and vegetable peels, etc. Adding fertilizer that is low in phosphorus and high in potassium content will also help preserve the color of delphinium blooms.
Highly alkaline (chalky) soil makes it almost impossible for delphiniums to bloom blue, which is why diligence is required to maintain the soil at the correct PH levels. The ideal PH is 5.2 to 5.5 PH.
Protecting Roots from Cold Damage
If the delphinium is planted in a container, the container should be wrapped in bubble wrap to avoid damage to the roots in severe weather.
Plant Delphiniums next to a building or other form of barrier to protect from strong winds. If the climate turns severely cold in local winters, avoid planting delphiniums outdoors. Container planted delphiniums will be easier to protect from harsh weather changes.
Delphiniums thrive in sunny areas, with a temperate climate. The soil should be fertile and they require generous watering every 10 days. To boost flowering, the plants must be fertilized regularly and removal of old spikes will encourage a second flowering in late summer.