Ipomoea for northern climates

320083817243-0001@t-online.de 320083817243-0001@t-online.de
Sat, 17 Dec 2005 09:49:39 PST
Dear All,

I grow a non-tuberous perinnial Ipomoea learii "large form" which is far 
superior to the ordinary one seen in many warm countries covering fences and 
trees. I grow it directly under the glass of my unshaded greenhouse to produce 
natural shade below it. It flowers spectacularly with huge, at least 4 inch 
wide flowers that start royal blue and turn pinkish at the end of the day. It 
does flower outside but in a cool and rainy summer it will produce lush growth 
but little flowers.It was pest free all the years but last summer I had a 
spider mite problem as never before and even this plant was affected. It has 
never set any seed even not after hand pollination and I guess it may be a 
polyploid. Another non-tuberous perennial Ipomoea is I. alba (Calonyction 
album) with stunning saucer size and shaped white scented night flowers, a 
perfect performer outside. This can be very easily grown as an annual from seed 
or overwintered cuttings.

The best tuberous Ipomoea I grow is I fistulosa. This is the name on the label 
when I bought it but I am not sure if this is correct, could be I. platense or 
a form of it. It has formed a massive clefted tuber that I have to plant above 
soil level in a very large container, otherwise most of the volume of the 
container would be filled with tuber. It goes fully dormant in winter and is 
stored in the cellar and becomes bigger every year. In spring it explodes into 
growth and produces  a bunch of wiry strong twining stems that will have 
palmate leaves and in summer MASSES of 3 inch purplish pink flowers with a dark 
purple throat. It is always grown outside and performs well every summer the 
better the warmer it is. No seed as well, maybe also that Ipomoeas are self 
sterile? But it propagates easily from stem cuttings that will also form a 
tuber but are grown without dormancy through their first winter. Upon request I 
would be happy to propagate this plant but there would be waiting time for a 
tuber large enough to be shipped.

I am absolutely sure that these plants would perform anywhere in the US and 
even Canada (in summer). If light intensity and heat here in Germany makes it 
perform well, it would do even better in the US or Canada because compared to 
Europe a comparable USDA zone in North America is far more south! For example 
Frankfurt in central Germany lies 50° northern latitude and has wine growing 
climate and roughly USDA Zone 7 (USDA Zones cannot really be applied in 
Europe). 50° northern latitude in North America equals northern New Foundland, 
Winnipeg or Vancouver. All of the US except Alaska is south of that. And in 
Europe for example all of Great Britain is north of that.
Myself I live near Hannover which is roughly 52,5° north and roughly Zone 6-7.
I think the tropical forms of Ipomoea bred for tuber production for food are 
not really meant to flower altough they sometimes do so. But the more temperate 
ones are very good garden plants in warm summer gardens.

If the staff of the Phoenix Botanical Gardens sweeps away the seed of Merremia 
aurea...... why not pick up some and give it to the seed exchange? I would be 
very interested in some of these seeds!

greetings from northern latitudes and 20cm of fresh snow..... Uli

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