Verbascum dumulosum from cuttings

[Martin Baxendale]

Does anyone have any advice or tips re. propagating Verbascum dumulosum from cuttings? Best time, length of cuttings, rooting material, open or closed atmosphere, etc.

I have a very straggly old plant tumbling from the top of a wall that really needs to be cut right back and the straggly bits rooted as cuttings. But the last time I tried this, in a closed propagator, none of the cuttings rooted and they all eventually dried up and perished. 

Any ideas?

[Lesley Cox]

Hi Martin,
     I have done cuttings of both V. dumulosum and V. `Letitia' the same way. Take them in spring or any time when there is vigorous growth but not actually in flower (they'll do then too though, if you remove any incipient buds),  remove the lower leaves and trim the upper ones. I like the stem to be a total of about 7-8cms, semi-ripe, or just beginning to harden a little. They're very furry of course but you can feel if they're right. Firm and not able to be squashed between the fingers easily.

I dip the last couple of centimetres in a liquid rooting hormone at the recommended strength for about 5 seconds (you can hold half a dozen at a time to dip). The product I use is a NZ invention called Liba 10,000 and is very good for difficult to root species, and was, in fact, formulated for use on protaceae and feijoas.

Then I insert about a third of the total lengrth in damp gritty sand with a gritty compost beneath it. I never put any furry leaved plant in an enclosed place but just leave them out of the sun but with full air movement. The 2 verbascums take maybe 3-6 weeks (depending on warmth and the season) to root enough to pot on. They'll need watering from time to time of course. Any enclosure such as a plastic bag or propagator will almost certainly make the leaves go mouldy and drop off.

Is this helpful?

[Martin Baxendale]

Lesley, thanks for the detailed guidelines. I thought you might be the first to offer advice. I suspected that putting them in an closed propagator might have been my biggest mistake, and that keeping them open to the air with good ventilation but out of direct sun might have been better. The leaves didn't drop, but they did quickly turn beige rather than grey-green! It was the large size of the flopy leaves (it's actually V. dumulosum 'Large-Flowered Form' and has pretty big leaves) that made me worry about leaving the cuttings open to the air. I should have thought it through more carefully and maybe even tried them half enclosed and half not. Never enough time to think things through as much as I could! But that's life, eh?

[Martin Baxendale]

Lesley, I think I may also have taken them a little too late in the season. Can't recall exactly, but I think it may well have been in the summer (when growth had slowed down).

[Lesley Cox]

I've done them in both summer and autumn as well Martin, so worth trying then if that's when it is, if you see what I mean, even try a few now and then over 4 or 5 months. When you've got some rooted and potted on successfully, cut back the old one quite hard and it should come away well if not too early in the season, say late spring, early summer.

[jomowi]

Martin

I have never taken any particular precautions and had a good success rate.  I just strip off the lower leaves and push the cuttings into a pot of fairly open mixture, keep fairly dry and give some ventilation out of the full sun.  They usually root at almost any time of the year.  For me in a sheltered sunny spot fairly close to the house V. dumulosum will survive the winter without any trouble, for several years until it gets too woody at the base.

Brian Wilson Aberdeen

[Martin Baxendale]

Thanks Brian. That chimes with Lelsey's advice. Looks like my big mistake was definitely putting them in a closed propagator instead of keeping them open to the air and well ventilated. As I recall, the weather was quite hot when I got around to taking the cuttings, so I must have been worried about them flagging and decided the propagator would be safer.

Interesting (and encouraging) that you didn't even need to use a rooting hormone dip. I'll try some with hormone and some without.

V. dumulosum is winter-hardy outside here too, trailing down a south-facing sunny wall almost on the street. It gets tatty if we get hard forsts but usually perks up again in spring.