TOW Oxalis
Tue, 11 Nov 2003 14:43:58 PST
Dear All,

Thanks to Robin for the very good introduction to the genus Oxalis. Being an 
Oxalis enthusiast for many years I like to see the genus getting much wider 
attention now, there is also an Oxalis group on Yahoo.

There are also some very nice summer growing Oxalis which are easier to grow to 
their full beauty in frosty climates. I find the winter growers do not develop 
to their full potential under glass even in the brightest position because we 
have so very short days and often overcast skies at this time of the year in 
northern Europe.

There are some summer growers which I will distribute in winter when they are 
fully dormant, some may even be hardy but then this may cause the potential 
risk of them becoming weeds. There is a particularly nice tall growing plant 
form Ecuador (which I traded with nothing but an accession No) with mauve pink 
flowers with very dark centres in umbels high above the leaves, it may even 
bloom year round when kept in the appropriate climate. It needed a few years to 
develop to its full beauty, I suspect that some Oxalis do NOT like to be 
transplanted every year, most do not mind, though.

There is also Oxalis articulata which forms finger-like tuberous stems above 
ground. it produces mounds of fresh green leaves almost invisible under masses 
of pink flowers, a nice edging plant and never a weed. This one definetely 
flowers all year in suitable conditions and is widespread in mild European 
gardens and is perhaps hardier than expected.

There are always a few pots in my Oxalis collection that do not show any growth 
the odd year. I never throw these away as Oxalis can stay dormant for many 
years without dying, they often come from extremely arid areas where is does 
not rain for a very long time and are simply not used to grow every year, I 
suspect. However, there may also be other reasons for Oxalis not 
growing........ I now use the wire nesh system to prevent mice from eating the 
bulbs out of the pots, but I had to learn the hard way...... before I used 
sqare pieces of not too fine wire mesh cut to fit firmly into the pots I lost a 
certain number of Oxalis to mice.

The Wiki pages on Oxalis are very nice and I was able to identify some of the 
plants I grow (but having doubts about O. incarnata, there is nothing red about 
it as the name implies) O "incarnata" is a very nice plant in a hanging basket 
with masses of scented flowers in spring in my greenhouse. The bulbils sprout 
wherever they fall onto other pots but so far it has not become a weed with me. 
But I have seen a mediterranean garden where it formes a solid mat on many 
beds...... Frost immediately kills the whole plant , so be careful in frost 
free climates.

Some of the nicest Oxalis are not weeds at all but are painfully slow to 

For substrate I use equal parts of perlite, seramis and a peat based commercial 
potting compost. This is a low weight substrate which is essential as the pots 
are in trays on a not too solid shelf under the grenhouse roof. It is also 
well aerated holds water and drains fast at the same time but the 
ingredients are not cheap. They get plenty of water while in growth and MUST 
NOT dry then and also get 2 or 3 waterings with ordinary strength liquid 
balanced fertilizer. When the greenhouse gets warm in spring dormancy begins. 
This can be retarded for better bulb size when the trays are moved into the 
open garden but care must be taken to avoid late frost. Once dormant it is 
important to keep them totally dry AND WARM, heat seems to stimulate bud 
formation. The internal biological clock of the plants is then set on again 
when weather cools in late summer and sprouting begins.

All the best, greetings from Germany, Uli

More information about the pbs mailing list