Tropaeolum success

Jane McGary
Sun, 15 May 2005 10:51:24 PDT
Mary Sue wrote:

>I have germinated seed of Tropaeolum on occasion, but even then lost it 
>later. I had no luck with some T. azureum seed that a kind friend from the 
>UK gave me last fall. I was so disappointed. Anyone with successful 
>methods for growing this from seed please speak up.
>So it was with low expectations that I sowed T. brachyceras that I was 
>lucky enough to get from the NARGS seed exchange this year. I'm now 
>wondering if I need to grow the ones I have in my greenhouse if I want to 
>get them to bloom. Maybe I'd have better luck. Has anyone in our group 
>figured out a successful way to grow Tropaeolums from seed? Does the time 
>you start them matter? Clifton suggested day length may have some effect 
>on T. azureum. Does the seed need to be soaked first?

I believe the seeds in the NARGS exchange did come from my plants and am 
glad they found such a good home. I've just been collecting some more seeds 
from the same plants so there may be a few available. The seeds have a 
fleshy aril which must be attractive to ants, because volunteer seedlings 
are popping up here and there in the bulb frames. I'll let them grow 
another year or two before harvesting them, even though, as Mary Sue 
mentioned, they are eager to seize on anything nearby and climb it. It's 
not unusual for this and some other Tropaeolum species to flower very young.

I've grown T. azureum from seed but lost it after two years. I may have let 
it dry out too much. When I saw it in the wild, it was growing near the 
base of a big cliff among tall shrubs (protection from goats, no doubt). 
Even though the area is very dry, I think there was moisture seeping 
through in that area. The seed is notorious for erratic germination.

In fact, I think most Tropaeolum seed is unpredictable. This year I got 
good germination from T. tricolorum and hope it is from an inland 
population rather than coastal. The forms in commerce are not very 
cold-hardy and I have lost them at about 20 F, but I've seen it growing 
just below melting snow in the Andes as well as within sight of the 
Pacific. I have also grown T. hookerianum and T. incisum from Flores & 
Watson seed collections. T. hookerianum is proving very slow, perhaps it's 
a bit cold for it in the bulb frame, but it has been there 5 years. T. 
incisum lay dormant for a year after repotting from the seed pot -- another 
peculiar behavior of this tuberous genus, so don't throw away pots that 
show no activity for a year or even two! Now T. incisum is about a foot 
long; it starts into growth later in the season than the others.

My friend David Hale grew T. polyphyllum for years in a half wine barrel 
which he moves indoors in winter. It hangs over the sides of the barrel and 
looks very attractive.

I do find T. brachyceras the easiest to grow of all the small species, and 
it is quite cold-hardy, growing and flowering without a check right through 
temperatures down to 20 F in the bulb frame. I put one outdoors last summer 
to see what it would do, but it didn't come up; however, I hope it may just 
be resting, as mentioned above. In Mary Sue's garden, this species should 
be fine outdoors. It doesn't need to be totally dry in summer, either. It 
is a delicate-looking climber with a great many bright yellow flowers.

Jane McGary
Northwestern Oregon, USA

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