We've recently had a new glasshouse constructed / installed at the Lakeside garden, part of my legacy here as Head Gardener.The dimensions are 10×8 ft, facing due south to receive plenty of sunlight, the ideal aspect being east / west for a glasshouse siting.
It's time to push on with semi ripe cuttings of hardy perennials, and my tasks are currently -
- Gaura Butterfly Rose (cuttings on bench, bottom image)
- Salivia involucrata (Rose Leaf Sage)
- Penstemon selection : see HPS Blog Archives, my blog on Propagation of Penstemon cuttings, 21st Nov 2015, updated 16th Jan 2018.
All cuttings are taken at a length of approximately 15.24 cm ( 6 inches) Gaura Butterfly Rose, I trialled for Hort Week Website analysis section ( parks & gardens) .
As with all cuttings, I cut back several centimetres off the top section to firmer growth material, this initiates stronger shoot formation. The same applies at the bottom end of the plant growth, ensuring stronger root formation is initiated. The second cutting from the left of Gaura Butterfly Rose ( image) is an example of cutting material I wouldn't use as it's too thin, and therefore less rooting potential.
A gritty mix of Horticultural grit × 1 part - 2 × peat free compost will suffice to strike semi ripe cuttings. I also use John Innes seed compost to root cuttings. I've found that hormone rooting powder accelerates root formation, but it's not a requirement and most cuttings will root freely without it with a good gritty mix or seed compost.
Cuttings can also be successfully rooted in pots of Horticultural grit/ perlite. No placing of small bags are necessary over semi ripe cuttings, they thrive on cold air circulation and lower night temperatures. Bottom heat from a bench is also not required. Cuttings will start to root in approximately 6 weeks, and build a network of roots to pot off into larger pots in early spring.
The glasshouse at the Lakeside will remain a cold unheated glasshouse through the winter, which many hardy perennials can be propagated by cuttings and seed.
A Winter guideline of a minimum of 32° fahrenheit will successfully root cuttings, and minus temperatures with a fleece cover still works well, or into a cold frame. Seed stratification comes into its own, and is another story, particularly for Alpines.
Kevin Line is Head Gardener, Lakeside Hotel Garden, Cumbria, and has worked in the industry for 45 years. Kevin writes for Hort Week, Professional Gardeners'Guild, and The Alpine Garden Society.
Kevin Line is Head Gardene, Lakeside Hotel Garden, Cumbria, and has worked in the industry for 45 years. Kevin writes for Hort Week, Professional Gardeners'Guild, and The Alpine Garden Society.
