Dormancy problems in Ornithogalum dubium

Mary Sue Ittner
Mon, 22 Jul 2002 16:09:35 PDT
Dear Paul,

In December we had a very interesting discussion of this subject on the Australian images list after someone posted an image of Ornithogalum dubium. Lyn Edwards who like you lives in Canberra had told about losing some orange ones like you have that bloomed themselves to death and others seemed to have more luck with yellow flowered forms. I have had experiences like you have had of their not coming into growth. What is the climate like in Canberra?  Here is what I wrote then with a few changes as I see it is still relevant and will save me some time writing it all over again:

Subject: Ornithogalum dubium

Dear Lyn,

I just wanted you to know that you are not the only one to lose Ornithogalum dubium. I am still trying to figure out how to grow them so am interested in all the tips you all are getting.

We discussed this on the IBS forum a number of years ago. Lauw de Jager from France could never get them to grow and Mary Irish in the Arizona desert could never get them to last more than one year. I keep trying. The first ones I bought never bloomed nor did they return. Since then I've
received bulbs from two different sources. They both bloomed but the first never came back and the second set of three bulbs spent the year following their blooming underground but two of them are up now which is promising.

I also got seed from Silverhill which germinated in amazing numbers. I wasn't confident so sowed it too thickly. I had heard Rod Saunders say in a talk that in Israel they can grow these to blooming size in a season, but mine didn't get very big and most of them did not come back up the next season after they went dormant. He didn't say how they did it. Perhaps they
had constant light and fertilizer.

The advice I have gotten is to feed them well and shelter them from our over abundance of rain. And Rod suggested I try to provide a warm summer so I guess they need to be in my greenhouse.

I think what I am learning from all of you is that they should be watered year round, but probably not a lot.  If you read where they are found in South Africa they are both
in winter rainfall areas (and areas that don't get a lot of rainfall even then) and areas that get year round rainfall (Port Elizabeth I understand gets most of its rain in spring and fall but some year round). Since I have been watering my Ixia viridiflora even when it is dormant it is doing better. I watered the Ornithogalum dubium last summer which is maybe why at least some of the bulbs have come up this year. Maybe they were descendents of bulbs grown in areas with year round rain fall.

Mine have not put up multiple blooming stalks and are just about dormant now. I am hoping that if I move them to a warmer place and give them an occasional drink they will come back for me next year, but I haven't dumped them out to look.

Alberto Castillo also provided some helpful tips to explain why some might bloom and die afterwards. I am hoping he won't mind my passing them on:

 This problem of Ornithogalum dubium bulbs dying away like this
suggests several possible causes
a)      inadequate overall temperatures
b)      lack of watering during the critical period when bulbs really fatten for
next year (between flowering and the onset of dormancy)
c)      you let the young bulbs  set seed (this is very detrimental to all bulbs,
as in nature they normally do not set seed or even flower every year)
d)      a fungus disease that destroys them due to excessive moisture once
dormancy is on
e)      improper depth

   The South African species of Ornithogalum are very prone to disease and
it is important to start with healthy bulbs,  like those of a source that
grows them from seed (you have at least a superb one in Australia). Our
Ornithogalum dubium grow in 16 cm pots in full sun and in late Spring they
flower profusely and  if allowed to, set seed. By the end of the year they
go completely dormant but the bulbs are formed like in any other bulb. They
are grown in our standard mix for them: 1/3 sterilized proprietary compost,
1/3 horticultural perlite (no dust) and 1/3 crushed rock.



Years ago Cathy Craig was keeping track of a very long blooming Ornithogalum dubium. If I haven't made this so long she has stopped reading, Cathy did your plant come back in subsequent years?

Mary Sue

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