oxalis hardiness

[Jean-Patrick AGIER]

Hello,
I bought this oxalis last year from a nursery. They consider it quite hardy for the UK. But I'm not a specialist on these plants. I know some are like weeds but can I leave my pot outside? with or without protection? It's still outside and thriving and flowered profusely since last spring.
I have a sheltered balcony south-east facing and usually winter temperatures can fall down to -5° here. Last winter I've kept it indoors for I was not sure of its hardiness.
Thanks for any advice
J-P

[Darren]

I seem to recall in the article on bulb frames in the september 1998 AGS bulletin (the special bulbs issue) that this was the species which filled the authors bulb frame. I could be wrong about where I read it- perhaps someone with a copy to hand can check?

[Luc Gilgemyn]

I've lost it twice outside in the Garden during Winter... 

We can - occasionally - get minimum temp's down to -10/15 °C - fortunately these temps have become exceptionnal over the last 10/15 years or so, but we did have
-14 °C last Winter...  )

I don't think it's hardy, but I wouldn't know what the bottom temperature is it can stand ?

[Lvandelft]

I seem to recall in the article on bulb frames in the september 1998 AGS bulletin (the special bulbs issue) that this was the species which filled the authors bulb frame. I could be wrong about where I read it- perhaps someone with a copy to hand can check?

I did read the same and since I kept it always in pots.
Under glass they will withstand temps. of at least -10 C. We kept them mostly in an unheated glasshouse.
But when drainage is very good in a covered bulb bed they will survive too.
A little effort is paying itself because it is a beautiful plant.

Oxalis obtusa pic.

[Rob Potterton]

Hello J-P. Oxalis obtusa is not hardy in our little corner of UK (central Eastern England) suffering badly outside during winter through the usual wet / cold combination. I would agree with comments above - cold greenhouse or frame that gives overhead protection from rain and a degree of protection from frost would ensure this species flourishes.

[Sinchets]

Oxalis obtusa is one of the species we have outside in the rock garden here. It isn't as happy as C.brasiliensis, but they are both bulking up from having been eaten, or dug up, by voles 2 years ago.

[Maggi Young]

I seem to recall in the article on bulb frames in the september 1998 AGS bulletin (the special bulbs issue) that this was the species which filled the authors bulb frame. I could be wrong about where I read it- perhaps someone with a copy to hand can check?

Darren, yes, it is Oxalis obtusa.

Though earlier in the article Bob Wallis speaks of "filling " the frames with "an old lawn mower, two dangerous ladders,old concrete blocks, brick batts, small pieces of old stone walling, a defunct TV sets,numerous old paint tins and copious amounts of plaster....." 

[Darren]

Thanks Maggi,

 I think the Wallises might have once lived in our house - we found similar items under the shed when we demolished it..plus bits of cars, motorbikes etc. We have pictures of the heap somewhere and perhaps a year later I can look at all that excavation work again without shuddering!  The neighbours reported seeing a cement mixer being buried once also but that must still be lurking somewhere else.


I once grew O obtusa in a frost free glasshouse but eventually gave it away. I found that the slightest bit of botrytis on a dead flower or leaf down among those finely packed thin stems and it went through the whole potful very quickly, rendering the remains very unsightly. It is probably better in a well ventilated frame in damp but fairly mild areas like ours, if spread can be contained.

[Lesley Cox]

I once grew O obtusa in a frost free glasshouse but eventually gave it away. I found that the slightest bit of botrytis on a dead flower or leaf down among those finely packed thin stems and it went through the whole potful very quickly, rendering the remains very unsightly. It is probably better in a well ventilated frame in damp but fairly mild areas like ours, if spread can be contained.

The same problem can occur in the open out-of-doors Darren if the foliage is extremely dense. It has happened here a couple of times with O. palmifrons and O. massoniana, both hardy enough.

[Darren]

Thanks Lesley - that actually makes me feel rather better. I was worried something was wrong with the way I grew it.  The most amazing example of this I've seen was in a crammed garden centre (20cm) pot of corydalis flexuosa which went from one infected shoot to total collapse in two days.

[Lesley Cox]

Yes Darren, it happens so terrifyingly quickly. No use thinking - as I often do - "I must do something about that." It's already too late. For known sufferers from botrytis such as potted frits or lilies, and the oxalis I mentioned, I'm at last learning that prevention is better than cure and spraying or even dipping pots, with/in a systemic fungicide before there is any sign of the disease. I now drench frit pots before they are even through the surface.

[Jean-Patrick AGIER]

Many thanks to you all for advice. I'll consider protecting my pot will be the best issue.
About botrytis and fungal diseases, could it be a good idea to prune the plant for the bad season which could help to prevent any attack ( no leaves left on the pot ). Then the bulbs could start again in spring?

[Darren]

Hi J P - the trouble is that they are summer-dormant and I don't know if they would produce any new leaves in spring as they will be trying to go dormant, plus it would weaken the plant to do without leaves for much of its growing season. Anyone else tried this?  And can it be persuaded to grow in summer instead?

[gote]

This kind of growth pattern is very diffult in northern Europe. I have never been able to grow Orchis and its relatives for this reason.
They habitually send up leaves in the fall when it starts raining "at home" then the leaves freeze to death if the plant is outside and indoors the light is too poor.
At a time I toyed with the idea to try to keep the plants warm over the winter to make them believe that it is still the dry summer season.
My hope was that in the spring they woud believe it to be fall and grow happily in our summer instead of going dormant.
has anybody experimented with this?
Göte

[Darren]

I am told that freesia, sparaxis bulbs etc sold in spring for summer bedding have been treated as you describe Gote.