ARS South Australia Newsletter – June 2018

  • Date: 3rd June 2018
  • author: Richard Illman

STRIKING CUTTING THE EUROPEAN WAY

Whilst they take their cuttings at about the same time as we do, that’s where the similarity ends. Their striking medium is pure, shredded, coarse Swedish peat. Cuttings are inserted directly into this in either a closed box as we do or a misting unit that can provide 100% humidity. They say the cuttings strike in 4-6 weeks and when growth starts the flower bud or vegetative bud on the top of the stem is removed to promote branching and the cuttings are treated with weak liquid fertiliser. After 3 months they are transferred into individual 100 mm pots, again in pure peat, fertilised regularly and can usually be pruned again within 6 months, producing a plant ready for sale within a year.

In Germany, the majority of Rhododendrons are struck as cutting grafts. Here a cutting of both a suitable root stock and a desirable scion are grafted together using a simple oblique cut across each stem, leaving about 1 cm of the understock protruding at the base. They are then treated exactly as above. The main nursery in this area of Germany produces over 1.5 million plants by this method a year. This process of grafting onto an understock, generally Cunningham’s White which is tolerant of slightly alkaline conditions, enables rhododendrons to be grown where the soil conditions are not suitable to growing plants on their own roots.

We observed in most of the gardens rhododendrons were grown on the surface of the soil in a raised bed of shredded coarse Swedish peat. In some places we saw plants growing from seed directly in these beds.

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