How to Grow Delphiniums
Dig about eighteen inches deep and three feet wide and mix composted manure or worm castings into your soil. Top dressing composted manure or worm castings every spring is helpful. Delphiniums are heavy feeders so to produce tall bloom spikes, it is recommended you sprinkle some all purpose Gaia Green organic fertilizer (4-4-4) every three weeks until they bloom.
Plant them in full sun for optimum growth. Gently tease the roots loose if they are tightly wound. When planting do not cover the crown of the plant. If you do, it will rot. When placing the delphinium in your garden, allow a three foot diameter for future growth. They need good air circulation to prevent issues of mildew and fungal disease from occurring.
Complete planting instructions for anything you may grow.
1. Dig hole
2. Add worm castings or compost into the hole
3. Mix with your existing soil
4. Re-dig the hole
5. Place plant in the hole
6. Mix 1 tsp. of Root Rescue (mycorrhizal fungi) with water in a 7 liter watering can.
6- Pour some of the Root Rescue solution on the roots in the hole
7. Cover half way with soil
8. Use a mug/scoop and add a circle around the plant with the Gaia Green 4-4-4 Organic Fertilizer.
9. Cover with soil to the top.
10. Water in with more Root Rescue.
11. Fertilize with Gaia Green Fertilizer 4-4-4 and top dress your gardens yearly with worm castings or compost.
Please note: The Root Rescue is applied only once for the life of a plant, shrub or tree. It can be applied when planting or to an existing garden that has never had mycorrhizal fungi applied. When plants or moved or divided the Root Rescue should be reapplied.
They need to be staked to prevent the tall bloom spikes from breaking. We have found the best plant support system is a grid system with two powder coated steel stakes. The circular grid holds each bloom individually. This plant support system should be placed around the middle of May to allow the plant to grow through the grid. As it grows up through the grid, gently slide the grid up the two stakes.
After blooming, cut back the finished bloom stems right to the ground and dispose of all old foliage. Delphinium stems are hollow and this method does not allow any water to accumulate in the stem and potentially rot the crown. Do not cut off any new foliage that is close to the ground. This is the growth to encourage re-bloom in the fall. This is a good time to sprinkle some more all purpose 4-4-4 Gaia Green organic fertilizer and water it in.
Do not cover or protect them in the winter, as the snow insulates them. It takes about two years for delphiniums to become fully established. If you wish to divide them, it may be done after five years. It is best done in early spring when the plant is approximately three inches high. If you have a problem with slugs, Safers Slug and Snail bait works well. Also removing all foliage in the fall helps to control any slugs from wintering over. Powdery mildew can be problem in a dry garden so keep your delphiniums well watered when they are growing. Most perennials only require one inch of water per week.
Below are some Delphinium elatums we grow and sell here at Plant Paradise Country Gardens. Click on any photo or plant name to see more information about each plant.
Delphinium elatum Cobalt Dreams
Delphinium elatum Morning Lights