The Delphinium is and always has been the Queen of the Border, the back border in any perennial flower bed planting. They are stately, magnificent and beautiful. They are easy to grow; all they need is a loose soil, lots of sun, plenty of water and regular feeding. A loose, well drained soil is imperative. Of course, the main bloom time in Auburn, New York is around the end of June but if you are lucky, that secondary bloom season should be appearing in your garden right about now. And, if you have several varieties you just might have flowers throughout the season.
Let’s start at the beginning, Queen of the Border.” It refers to old English cottage gardens, usually planted against a fence and the delphinium was the plant at the back of that border garden, and as the plants were placed, tallest in the back and ground covers in the front, you had a magnificent setting.
Delphiniums are part of the buttercup family, the Ranunculus. Different kinds are native to various areas across the northern hemisphere. Actually there are some 300 genera and countless hybrids. In our American gardens there are two predominant types, the Belladonnas, shorter, dark blue, light blue and white with frequent re-flowerings throughout the summer and the Pacific Giants. These are tall ones. In the 60’s, when I grew delphiniums commercially it was not unusual to have 6 foot spikes. Since those earlier days, when the color selection was not great, breeders have brought us through the whole color spectrum. Princess Caroline, named after the Princess of Monaco, a very pale pink was my personal favorite in this series.
While we propagate ours from seeds, the British have gone a different route. Once a hybrid has been developed new plants are developed from cuttings and plant division. This, of course, ensures that there will be no variation and when you buy a Madam Langdon delphinium, the growth and flowers will be the same no matter where you find it. In recent years a whole new series of hybrids has been develop in New Zealand and the Dutch are forever coming up with new varieties.
Now, for the plant in our gardens. Delphiniums will thrive in full sun, and will do quite well in light shade. Mulch your plants in early spring to help retain soil water and keep the weeds down. These plants should never dry out. Delphiniums are very hungry plants and need regular, and reasonable, feeding during the growing season. I like to use a low nitrogen, liquid fertilizer. As your flower spikes begin to develop it is very important to stake them, especially if you are growing the Pacific Hybrid types. The stems, heavily laden with flowers, are hollow and will snap over with even the lightest wind. Here is a very important tip. Sometimes the stem does not seem to take on enough water and the florets begin to wilt. Hang it up side down and fill the hollow stem with water and the flowers will come right back.
In our area, even though it is considered a perennial, plants will produce beautiful flowers for only 3 or 4 years, so continual new plantings are very important.
In the fall, be sure to cut all the stems down to ground level, you eliminate winter hiding places for snails and slugs and other pests. The only disease that seems to bother them is powdery mildew and that is easily controlled with fungicides readily available at our home improvement stores and garden centers.