Propagation of Tropaeolum
320083817243-0001@t-online.de (Sat, 12 Jan 2008 17:41:30 PST)

Dear All,

Dividing Tropaeolum tubers? I would never dare to do so. What I did in the past
is cuttings. The difficult bit with cuttings is that Tropaeolum shoots have two
stages of growth, the first stage is the growth stage where they only produce
leaves and shoots and the second stage is the flowering stage where they
produce buds and flowers. I read in an article, I think it was the British
Alpine Garden Society, that only cuttings of the growth-stage-shoots will root.
I tried and it worked. The sheer thin-ness of the shoots did not prove a
problem, but of course they should have some leaves. Both tip cuttings and
internodal cuttings worket but not 100%. The remaining shoot will branch and
grow on after removal of its tip but I agree it feels a little heartbreaking to
cut off a lot of shoot of perhaps a single plant. I also rescued bits of shoots
this way that "survived" slug damage to the main shoot. A cool to cold but
frost free greenhouse is the place to root them, I put the pot into a plastic
bag until new growth appears.
A big problem with Tropaeolums is that the tubers do not shoot some years,
sometimes not even several years in one go. Especially the small tubers formed
by cuttings or seedlings may die in this process, larger tubers can last for
years firm and healthy. I could not find out why this happens but found it
happens less if the dormant tuber is slightly watered during dormancy. The
worst species to do that with me is T. brachyceras. What is the experience and
opinion of other growers?

Bye for today. Uli