Growing Sunflowers.

Latest Update 18th january 2015.

Growing Sunflowers
  • Binomial name:                                   Helianthus annuus
  • Family group:                                      Asteraceae.
  • Classification:                                      Herbaceous perennial.
  • Mature plant size:                                2000mm high x 750mm wide.
  • Garden bed type:                                 Drip line irrigated. 
  • Recommended soil pH:                         pH tolerant 
  • Climate:                                              Warm temperate.
  • Geography:                                          Southern hemisphere. 
  • These giant daisies are a great feature if carefully placed in your garden. 
  • I grow mine in my vegetable garden to attract birds and pollinating insects.
  • The seeds are edible, and if pressed produce a tasty oil which can be used in salads.
Growing Conditions:
  • They grow well in heavy clay soil containing lots of organic matter.
  • Minimise soil disturbances to maintain a natural soil structure. 
  • Although they are perennial, I grow mine as annuals.
  • They grow best in full sun and are extremely hardy in hot dry weather.  However, they do benefit from regular deep watering.
Feed the Soil.  
  • Prepare the soil in July where the sunflowers are to be grown.  Removing any spent mulch or other organic materials from the surface of the soil.
  • Apply a 60mm thick top dressing of home made compost and cover it with fresh straw mulch.
  • Leave for 4 weeks to build up worm and microbe activity before planting the seedlings.
Growing Instructions
  • To propagate sunflowers allow a few plants to go to seed in winter.  Collect the dried seeds and save them for the following season.
  • I put mine in a sealed envelope and keep them in my seed box in the fridge (not the freezer).  They stay viable for years.
  • In July sow sunflower seeds in mini pots under glass.  Using a good organic seed raising mix sow the seeds about 5mm deep.  Soak the mini pot in a tray containing water about 10mm deep for an hour.  Transfer the pot into a mini Ecobed propagator under glass.
  • Transplant them into the prepared bed when they are about 100mm tall.  Space them 500mm apart.  
  • Apply a regular monthly foliar spray of aerated compost tea.
Organic Pest Control.
  • My sunflowers have been pest and disease free for many years, but can be effected by the following:-
  • Greenhouse whitefly.
    • Aerated compost tea toughens the plants foliage resisting whitefly damage.
    • Alternatively, control any infestations by spraying your crop thoroughly with organic neem oil as early in the whitefly's life cycle as possible.
    • Spray again in a few days to ensure second generation whitefly do not survive. 
  • Powdery mildew. 
    • A monthly foliar spray of aerated compost tea was a spectacular success last year with no sign of powdery mildew on any of my plants.
    • Alternatively a solution of 1 part cows milk to 9 parts water makes a reasonably effective organic pesticide against powdery mildew.  However, it needs to be applied early before this fungi gets well established, and frequently to keep it in check.
    • General:
    • Regular foliar sprays of aerated compost tea boost the natural defences of sunflowers by colonising the leaf surfaces with beneficial microbes.  These microbes defend the plant against airborne pests and diseases.
    • Similarly, proper soil preparation including regular applications of home made compost boosts the community of beneficial microbes, which defend the plants roots against plant pathogens.

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