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Author Topic: New Propagation Technique for Lithodora diffusa  (Read 15944 times)

GordonT

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New Propagation Technique for Lithodora diffusa
« on: January 31, 2014, 01:44:06 AM »
Last year I learned a new technique for propagating Lithodora diffusa. Most recommendations call for use of semi-hardwood cuttings to multiply this plant, but chance discovery taught me that root cuttings will produce vigorous plants more quickly than cuttings.

I have sheltered a 'mother plant' in our unheated polytunnel greenhouse, as insurance against our sometimes harsh winter cold. It has been a source for cutting material over the past few years. Last winter, it sent roots through the drainage holes of the pot, and into the sand floor of the greenhouse. Several robust leafy shoots were noticed where the root exited the pot, and before it vanished into the sand (ie: where the root surface was exposed to light and air)

After carefully lifting the potted plant, with it's new youngster attached, I cut the new plant away from its mother, and removed the parent from its pot. I decided to experiment with the unpotted plant, so I harvested several of the thicker roots, making sure these came from inside the pot (no shoots present).

The roots were potted up separately, with the cut surface set at, or slightly above the potting mix. No special care was given to these cuttings, they were kept evenly moist, and were set on the greenhouse floor. In short order, each root produced several shoots where the root was exposed to light and air. Plants derived from this method of propagation gained size far more quickly than my old method of using shoot cuttings and rooting powder. I did find that thicker roots were most likely to produce abundant growth. Although thinner roots also produced shoots, growth points were fewer in number and weaker in vigour.
Southwestern Nova Scotia,
Zone 6B or above , depending on the year.

johnw

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Re: New Propagation Technique for Lithodora diffusa
« Reply #1 on: January 31, 2014, 02:35:03 AM »
Gordon - Do try to get Lithodora 'Heavenly Blue' going.  It seems to be significantly hardier than 'Grace Ward' and for some reason has disappeared from the trade.  It should be great in the sandy soil of the Digby/Annapolis Royal area.  There was one here in Hfx. 6feet across growing on a mound with sharp drainage.

johnw - above freezing on Friday, it's been awhile.
John in coastal Nova Scotia

Carlo

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Re: New Propagation Technique for Lithodora diffusa
« Reply #2 on: February 01, 2014, 10:23:11 PM »
Nicely done! it's always useful to hear about people's experiences...especially when it takes them in a new direction.
Carlo A. Balistrieri
Vice President
The Garden Conservancy
Zone 6

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johnw

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Re: New Propagation Technique for Lithodora diffusa
« Reply #3 on: February 02, 2014, 12:29:37 AM »
Gordon  - I always thought the big one in Halifax was increasing by layering itself.  Based on your experience I now have to wonder if many of those shoots were not sprouting from roots on the exterior of the mat.

Heh Carlo, you have been laying low of late, late.......

john
« Last Edit: February 02, 2014, 12:38:16 AM by johnw »
John in coastal Nova Scotia

GordonT

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Re: New Propagation Technique for Lithodora diffusa
« Reply #4 on: February 02, 2014, 01:37:10 AM »
Thank you , Carlo! I found that I had fewer losses via root cuttings than by the traditional method of propagation by semi-hardwood cuttings.

After being exposed to the incredible variety of plants available in Vancouver, I find myself looking for anything new and unusual to add to our landscape, and to introduce to southwestern Nova Scotia. Lithodora Grace Ward was one of our favourites out west, but was unavailable locally. My partner and I now find ourselves growing new plants from seed, testing them in our landscape, and offering them for sale via our participation in a local "Rare and Unusual Plant Sale". My latest projects involve testing Pacific Coast Iris, Penstemons, and Arisaema  for Nova Scotian gardens.
'
John- I think you are right to suspect adventitious growth from surface roots. My first attempt with 'Grace Ward' here failed because of winter wet. I gave a plant to a neighbour, almost directly across the street from us, and it is thriving. The difference was additional drainage, and as much sun year round as possible. New plantings here are given a top dressing of gravel (ideally granite based).  I ought to look at 'Heavenly Blue' alongside 'Grace Ward' to see how they compare colourwise.
Southwestern Nova Scotia,
Zone 6B or above , depending on the year.

johnw

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Re: New Propagation Technique for Lithodora diffusa
« Reply #5 on: February 02, 2014, 03:57:49 PM »
Gordon  - The big Lithodora here grew on a raised hummock 2 ft above grade in grit-laced fast-draining soil.  Only problem is the more open the mix the easier cold can penetrate so it was a bit of a catch22 in snowless winters.

I think it was the winter of Dec 1990-April 1991that Heavenly Blue proved its hardiness in these parts - snowless, no rain, no snow for weeks and weeks on end. By no means extremely cold but the cold got into the soil.

johnw
John in coastal Nova Scotia

 

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