Tropaeolum pentaphyllum

Uli Urban
Fri, 17 Oct 2008 16:18:00 PDT
Dear All,

Tropaeolum pentaphyllum (ssp pentaphyllum) is a vigorous winter growing
tuberous species, even so vigorous that it can become a weed in a
greenhouse because it will entwine in all neighbouring plants. Its
flowers are rather insignificant: green with reddish-brown dots and a
short spur. It has a fairly long growing period for a tuberous
tropaeolum but will go dormant with warm weather in summer. I do not
know how hardy to frost it is, I have never tested with my plants but I
think it is not very hardy and is not suitable for outdoor cultivation
in winter cold climates below freezing. This is one of the easiest
species Tropaeolums to grow and I found them not fussy in their
requirements. During dormancy I keep all tuberous Troaeolums in their
pots (I grow all of them in plastic pots) warm and dry but not totally
baking dry like for example a tulip or Oxalis but in a shaded spot of
the greenhouse with some water from time to time. Some Tropaeolums have
the nasty habit of not sprouting at all for one or even more seasons. I
just discovered a shoot on a T. brachyceras that had not shown any signs
of life for several years! Nobody seems to know why this happens.
Seedlings may at first have a different growing pattern depending on
when the seed was sown but getting older they will take on the original
winter growth rhythm. Many bulb seedlings stay evergreen in their first
or second "dormancy period" which does not mean they really changed.
Myself I stopped growing this plant because it was too vigorous in my
greenhouse which in winter is full of tender plants brought in from the
garden where they spent the summer. 
For a good display of very charming flowers I recommend T. tricolorum.
It is dainty, not over-vigorous and sprouts reliably every year to
flower in late winter, dormant in summer.
There is a strictly summer growing Tropaeolum pentaphyllum ssp
megalopetalum which I have been growing for some years. it has two
bright red "ears" like Mickey Mouse and thus becomes quite interesting,
still very vigorous and needs a lot of space to scramble. Germination
from its blue seeds is quite erratic, there is some unripe seed.....
hopefully I will be able to distribute it when ripe before it freezes.,
This plant does not flower the first year from seed but will form a
tuber which will become quite substantial the following years and then
is a reliable plant.

Greetings from Germany...... getting cold now.    Uli

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