There’s fully as much difference between the older and the modern delphiniums with their long, gorgeous spires, as there is between old-time roses, gladiolus, peonies, and dahlias, and the newer creations.
If you’re a beginner, and close to a supply of the modern hybrids, buy not old plants (one year or over), but strong, young plants. If plants aren’t available in your neighborhood, order seeds of newer hybrids and follow exactly the instructions of the hybridzer in getting your plants started and out into the garden early. Purchase the best hand pollinated seed that is obtainable. It takes just as much effort and time to grow poor seed (you’ll see it listed as “hollyhock type”) as it does to grow the best. So, buy the best.
Delphinium plants wake up early in March, in fact, delphiniums start to grow actually before you know it in the spring. After that they like to be let alone. They like cool roots and summer mulches. They want good winter drainage.
Delphinium does not like deep cultivation. Keep the blade a good eight inches away. There is no part of the United States where delphiniums can’t be grown when these basic conditions and care are met. The gardener who wants change and variety will find that delphiniums are friendly in any color combination. For a brilliant effect, use intense blue shades of delphiniums with tall growing; buff Thalictrum glaucum to give a feathery note to the background. In strong contrast, plant the orange Croceum lily and the bright yellow Sundrop in the foreground. For a pastel effect use the Nankeen lily instead of the orange Croceum. Violas and `pansies in yellow and apricot, if. picked and shorn after the early-blooming season, will come back for another blooming period in the border.
When old plants start spring growth, look out for slugs! Spread the slug bait. Work bonemeal in around plants: Cultivate If you’ve a clump that’s been blooming more than two years, try dividing it. Dig it, hose it off, and cut it into three or four pieces, making sure each has a bit of live crown and good root. Dust surfaces with powdered charcoal, then replant divisions.
Wherever you live, try to finish planting by the middle of April. Get fall-planted seedlings out of the coldframe and into the garden. Transplant spring-sown seedlings. Keep delphiniums growing vigorously. This means cultivating and watering. When flower stalks appear, stake tall-growing ones, especially if soil is sandy. Use 7-foot stakes, 1/2 inch in diameter, painted green. Thin out a few of the spikes to encourage giant flowers. If you raise delphiniums just because you like them, don’t thin this first crop-the more, the lovelier.
Water flowering plants freely; irrigate rather than hose them, for too much sprinkling makes for mildew. If mildew does show up, as it’s likely to do in cool and rainy weather, spray two or three times with one of the mildew sprays, or dust with dusting sulfur. Cultivate between waterings.
When flowers fade, cut spikes off just above foliage, leaving a foot of old stem. Go light on water for two or three weeks to let plants rest. When new growth starts, cut old stems clear off. Into soil around each plant work a teaspoonful of plant food; water immediately, and frequently. To keep some second growth from blooming, break off some new shoots, leaving two or three.
Plant delphinium seeds in early August for bloom next midsummer. Seeds germinate best when fresh. The trick in hot-weather sowing is to keep the seed box dark and cool until germination, and then gradually to admit light and air. Keep soil moist but never wet. When three true leaves show, transplant to a shaded coldframe for winter. Spread sand; inch deep, around seedlings’ to discourage slugs. Set them in sunny, open places; dig deep and put in drainage. Lighten soil with peatmoss; enrich with plant food; sweeten with lime, if needed. Space plants 2 feet apart with crowns 2 inches below ground. Firm soil; water.
Delphiniums are their best when 2 years old, but with care produce good bloom for three or more years.
See to it that all delphiniums have good drainage, for if icy water stands around crowns, loss will be heavy. Delphiniums rarely need winter protection, even in zero sections. They don’t mind freezing; it’s freezing-and-thawing, and cold wet feet that are bad. When cleaning garden for winter, rake lightly around plants so as not to injure their crowns. Never move delphiniums when dormant.
Before the ground freezes, bring in a box of loam and sand to use in seed boxes. A good mixture for delphiniums is 1/3 loam and sand, 1/3 peatmoss sifted and sterilized.