The soil must be well drained, as they will not tolerate 'wet feet' during the winter. If your soil tends to be poor or heavy in texture, be certain to add ample amounts of sand and organic humus. When setting out plants, prepare a large planting hole, mixing about 50 percent peat moss, compost or processed manure with your existing soil. Add a little lime and a non-burning transplanting fertilizer as you plant. Be sure the crown of the plant is placed right at ground level.
Delphiniums are such rapid growing perennials.
They benefit from special fertilization and watering care. Then they will also require ample water during their rapid growth months of April, May, June and July. The enormous flower spikes, often reaching as much as eight feet in height, may need to be staked to protect the flowers from being wind-whipped, thus loosening and tearing the feeder roots of the plants, which could seriously hamper growth and flowering results. You can start new delphinium plants from seed at almost any time. From April to September the seeds can be sown directly into the garden.