diana chapman rarebulbs@earthlink.net
Thu, 20 Mar 2003 08:52:51 PST
Dear Mary Sue:

I can't be specific about which Oxalis species increase, and which do not,
since I still don't have my Oxalis notebook.  In correspondence with
Michael, it seemed to me that most of the ones he said didn't increase much
behaved the same way for me, although my climate is much cooler than that
of southern California.  There are some species I will probably never be
able to distribute since they have increased so little, or not at all. 
Oxalis gracilis behaves this way.  I think all the O. flava clones I have
do better in a deep (10-12") pot, as far as flowering is concerned. 
Although most O. obtusa and O. purpurea increase very vigorously, I have
clones of both that have hardly increased at all.

I most definitely agree that most Oxalis need a warm dormancy to flower
well.  The first summer I spent in Humboldt county was the coldest on
record, and some of my Oxalis didn't break dormancy until about the middle
of winter.  As far as they were concerned, summer hadn't happened at all
(it felt that way to me too).  I then started keeping all of them in a
greenhouse to warm them up, and this solved the problem.  I haven't found
it necessary to start watering them early to get them to bloom, either on
the cool coast of northern California or in the hot interior.  There are
many reasons why some Oxalis don't bloom.  Some seem to prefer crowding to
bloom reliably, some hate it and need repotting almost every year.  As for
Ken Aslet -- there are two clones in commerce, one that blooms very little
and one that is supposed to bloom more reliably.  Ken Aslet is mostly grown
for the velvety leaves.

In summary, I think the most important factors in getting Oxalis to bloom
are:  a warm summer rest with a distinct temperature drop in fall; a deep
pot; regular repotting.

Telos Rare Bulbs 

> Dear Paul and Mike,
> We discussed Oxalis on the Pacific Bulb Society list in our Northern 
> Hemisphere fall and also when to start watering in climates where there
> summer drought. Quite a few people (but not all as there always seem to
> exceptions) felt that you needed to start watering the South Africans in 
> late summer to get them to bloom properly. Lauw de Jager felt this was 
> crucial for many of the Oxalis or you wouldn't get them to bloom. They 
> would come up, but not bloom.
> I spoke with Michael Vassar at the IBS meeting in Pasadena about the
> of Oxalis I couldn't get to bloom. I am grateful I had this opportunity 
> since he is no longer alive. He suggested some of them needed hot summers 
> which you can provide in Australia, but I can't and so I moved my dry
> into the greenhouse for the summer and it seemed to help a few of them.
> also suggested a deeper pot for some of them. I had been growing them in 
> shallow pots because I had read that the soil would heat up better in 
> winter and that would help as they need warmth to bloom. That may be, but 
> some of them need the room for roots more.
> I have some evidence that all three of these are important. When I have 
> been away and started my Oxalis late so that neighbors wouldn't have to 
> water them or acquired them late, they have done less well. Some of the 
> ones that spent the summer in the greenhouse did much better. And I
> (!!) got blooms on one pot of Oxalis flava that had more of a root run
> was started earlier). Still no luck with Ken Aslet however, but I'd grow
> for the leaves. And it is notorious for not blooming so Lyn is to be 
> congratulated in getting hers to bloom.
> In spite of that I still have a number of Oxalis from trade or purchase 
> that aren't doing well for me. And I have clones of the same species that 
> are very happy. So I have concluded some just aren't happy in my climate 
> and I'm giving up on them.
> I spoke with Charles Hardman about a week ago and he said he has 
> representatives from all of Michael Vassar's collection and some never 
> increased or were vigorous (Diana Chapman has mentioned this before). It 
> would be interesting to know if they were the same ones that are a
> for me or if in his drier southern California climate he does better with 
> some and I do better with others.
> Mary Sue
> Mary Sue Ittner
> California's North Coast
> Wet mild winters with occasional frost
> Dry mild summers
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--- diana chapman
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