Ornithogalum failure to break dormancy

Nathan Lange plantsman@comcast.net
Sun, 07 Dec 2014 17:54:39 PST

One possible solution is to store Ornithogalum 
dubium bulbs completely dry and unpotted in a 
paper bag on top of a refrigerator, but I would 
only do this after checking the temperature there 
first to see if its warm enough (above 22C, 72F) 
and not too warm (maybe above 30C, 86F, which I 
realize is much cooler than your typical day time 
summer day in inland California, but I'm talking 
about constant 24 hour day/night temperature). 
Heating mats would be another option.

As I previously posted, 
http://www.jhortscib.org/Vol79/79_4/12.htm , this 
study suggests that the optimal Ornithogalum 
dubium bulb storage temperature for flowering is 
between 22C (72F) and 30C (86F) but it's hard to 
say without seeing the complete article and this 
study was very limited to only one, arguably 
short, storage duration of six weeks. Even at 
these temperatures, the percentage of bulbs that 
flowered was below 100%. Longer warm storage 
durations would likely increase bulb flowering 
percentages. At higher temperatures, 35C (95F), 
the number of florets per bulb decreased, so 
while the percentage of bulbs that flower may 
increase with increasing storage temperature over 
a given temperature range, the number of florets 
per inflorescence decreases. Similar results are 
often seen with other unrelated species requiring 
vernalization: over vernalization ensures 100% 
flowering but also results in fewer flowers per 
plant. The key is always to find that optimal 
temperature treatment that maximizes both flower 
number and flowering percentage.

An earlier study, 
http://www.actahort.org/books/430/430_34.htm , 
generally agreed with the one above and 
recommends storing harvested bulbs at 25C (77F) 
in addition to keeping them at 17C (63F) for four 
weeks prior to planting for potted plant 
production, although it's unclear from the 
abstract how these particular temperatures were selected.

Another source (Netherlands bulb industry?) 
recommends a "dormancy-breaking requirement" of seven weeks at 28°C (82F):


More information about the pbs mailing list