Growing Delphiniums in the Home Garden

Situation

  • Full sun preferred - successful in dappled shade but will need wide spacing.
  • Delphiniums are very hardy and tolerant of frosts. They will stand and even benefit from winter freezing.

Shelter

  • Good permeable shelter (tall loose shrubs or small trees) is required

Soil

  • Must be rich as delphinium are gross feeders. (Mulch and sheep manure work wonders)
  • PH neutral 6.0 - 7.0 but successful over a wide range
  • Well drained, particularly in warm areas: they must not get very warm, very wet feet
  • Keep as cool as possible with thick mulch (sawdust also helps prevent slug and snail attack)

Planting

  • Plant in Spring and Autumn
  • Give each Delphinium ½ m²-1m² of ground. Wide spacing helps control height; with close spacing plants grow taller.
  • Keep young plants moist

Support

  • Staking is essential for best results
  • If grown in a bed grow through raised sheep netting or other framework. Properly supported delphiniums will stand a lot of wind
  • Don’t plant right up against a tall wall - the wind will thrash them.

Plant Maintenance

  • Cut each spike down to 5 cm above ground after flowering; reduce water, gradually increasing again when new growth begins
  • Cut down and tidy in early winter, put slug bait down & mulch
  • Start feeding again when new growth is 5-10 cm high

Watering

  • Water well when in full leaf and growth is rapid
  • Do not over water when cut down after flowering but increase water again when new shoots are 5-8 cm high

Diseases

  • Powdery mildew can be a problem and spraying with sulphur regularly, backed up with other fungicides e. g "Greenguard" in hot humid weather should keep them clean.
  • If you use the same sprays as you do with roses you will get good result
  • More about diseases can be found at Michigan State University Extension

Pests

  • Slugs and snails are the only major pests - use Mesurol pellets to control these specially when plants are small and during winter.
  • In some countries caterpillars can be a problem. Spray as required.
  • Broad mite (a very tiny mite) can cause severe plant and flower distortion. Fortunately this pest does not seem to be very common in the Northern Hemisphere. If you see badly distorted growth or colour splotches on flowers cut this away and drench the plant with your favourite miticide... or dig it up and burn it.

Enjoyment

Sit and look at them as often as possible. If singing to them PLEASE SING IN TUNE or they wilt!!

Terry Dowdeswell

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Dowdeswell's Delphiniums - Wanganui, New Zealand