From my perspective as a Delphinium, timing is everything. The ideal moment for you to attempt division is in early spring, just as my new, green shoots are emerging from the crown and are about 2-3 inches tall. At this time, my energy reserves are high, having been stored in my roots over winter, and I am primed for vigorous growth. The cool, moist spring weather minimizes transplant shock and gives my divided sections the best chance to establish a strong new root system before the heat of summer stresses me. Alternatively, you can do this in early autumn after I have finished my main flowering display, allowing me to focus on root development in the still-warm soil.
Please approach this task with care. Begin by gently digging a wide circle around my base, taking care not to damage my extensive root system. Lift my entire clump from the ground and carefully wash the soil from my roots with a gentle spray of water. This allows you to see my natural growth points, or "fans," of foliage. Using a sharp, sterilized knife, cleanly cut through my crown and roots to separate these individual fans. Each new division must have at least one strong shoot (or growing eye) and a healthy portion of my fleshy roots attached. I am a perennial, and this surgical separation, while traumatic, is the most effective way for you to create genetically identical new plants from me.
Once divided, I am vulnerable. It is crucial you replant my new sections immediately. Prepare a new planting hole that is wide and deep enough to accommodate my roots without bending or crowding them. Enrich the soil with well-rotted compost to give me a nutrient boost. Position me in the ground so that the base of my shoot is level with the soil surface, not buried deeper than I was growing before. Firm the soil gently around my roots to eliminate air pockets and water me thoroughly. This initial deep watering is critical to settle the soil around my roots and help me recover from the shock of being divided.
If you wish to propagate me without the major disturbance of division, you can take basal cuttings. In spring, when my new shoots are still young and tender (about 3-4 inches tall), you can carefully twist them away from my main crown. Ideally, the cutting should come away with a small piece of the hard crown tissue, known as a "heel," at its base. Dip this end in a rooting hormone powder to encourage rapid root development and plant the cutting in a pot filled with a free-draining, sterile potting mix. Place the pot in a warm, bright location out of direct sun and keep the compost moist. In a few weeks, this cutting will develop its own roots, creating a new clone of me without you having to dig up my entire being.
