Tropaeolum dormancy

Rodger Whitlock
Wed, 14 Dec 2005 15:48:52 PST
On 14 Dec 05 at 0:21, Johannes-Ulrich Urban wrote:

> I also have made the experience that some Tropaeolum tubers just do not sprout 
> although they are firm and healthy.

I had this experience with Beauverdia sellowiana (Ipheion sellowianum, now yet some 
other genus) after it over-wintered in a cold frame. The tubers were firm and sound but 
no growth for several years.

I eventually concluded that the cold spell it had undergone had induced dormancy that 
could only be broken by warmth, so brought the pot into the house one spring and kept 
it warmer than usual. And, yes, the bulbs started to grow again, to my pleasure.

Deep dormancy has to be viewed from an evolutionary perspective: it allows the plant to 
survive a long period of unfavorable conditions. The trick is to successfully guess 
what the unfavorable condition is: too cold? too hot? too dry? and then persuade the 
bulb that good times are back.

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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