North American Fruit Explorers mailing list at ibiblio

[Clifford Cain - uk yahoo <cc_syorks@yahoo.co.uk>]

As the current thread is under way - just thought I would interject with 
a little background on Rhubarb growing here in the UK and how our 
warming climate is impacting upon its commercial production.
I am in the county (equivalent of State in USA) of Yorkshire where the 
Rhubarb Triangle can be found.  This is an area between the cities of 
Bradford, Leeds and Wakefield where rhubarb was widely grown 
commercially, producing forced rhubarb since Victorian times when the 
medicinal benefits of Rhubarb became prominent. Forced rhubarb lacks the 
acidity of green rhubarb, green referring to being grown outside rather 
than the colour of the stalk in this instance. A collection of over120 
cultivars was established at Harlow Carr Gardens and formed the national 
collection.  Since the RHS took over the gardens they moved the 
collection south to Wisley which is a shame because the reason Yorkshire 
grows so much rhubarb is due to the winter cold.  The crowns would be 
grown in the fields and fertilised with shoddy, waste from the wool 
mills , a traditional industry now as good as extinct in the area, which 
would provide nitrogen.  Coal mining was another traditional industry 
from which slag was used as a fertiliser.  The soils of the area are 
clay based and receive around 300mm winter rain.
Three year old crowns would be dug from the field in winter, late 
November to early December, as they should have been subjected to frost. 
The growers are finding that now they are having to chill the crowns 
after lifting because our winters are not as cold as they used to be and 
we are not seeing extended cold spells until January.  The crowns are 
then washed to removed soil, so as not to damage the emerging stalks and 
placed carefully into light excluding forcing sheds which are low sheds 
that are gently heated (50°F rising to 60°F, but no higher as this 
detrimentally affects the colour and firmness of the stalks).  The 
warmth brings on the crop, the retained water from the washing 
sufficient to keep the crowns healthy, though if they show signs of 
drying they will require watering, which is heated to the same 
temperature as the forcing shed, so as not to check the growth.  Once 
the forced crowns have been harvested they are disposed of, having no 
further energy in them, it is more commercially viable to vegetatively 
propagate by division of plants.  Apparently Rhubarb does not come true 
from seed, which is why they are vegetatively propagated.  Having said 
that there are a couple of varieties that are more stable from seed, 
particularly Victoria.  Rhubarb can also be propagated via root cuttings.
Rhubarb occupies the land for 3 years and as such needs a long, 7 year 
crop rotation
Rhubarb varieties are grouped according to the earliness of outdoor 
harvest.  So group 1s are very early (April 18-24), group 2s Early 
(April 25-30) and group 3s Late (May).
Here in the UK Forced Rhubarb is now a premium priced product, and the 
majority of that sold still comes from Yorkshire although the Dutch are 
copying the Forced methods.  Green Rhubarb, that grown outdoors, makes 
less of a sale.
As for the different types  you can simplistically divide into red and 
green stalked kinds (on the plant before cooking) but closer inspection 
shows that some stalks are concave, flat, thin, thick, ribbed or smooth. 
and permutations of the above. Combined with leaf characteristics of 
more or less downy or without hairs - results in 14 groups of rhubarb. 
Rhubarb is currently at the centre of trials on cancer treatments - 
utilising the root as per old Chinese medicine. The irony is that 
rhubarb used to be grown for the medicinal qualities of the root rather 
than for the edible qualities of the leaf stalks.
To celebrate the historical links with Rhubarb, Wakefield holds an 
annual Rhubarb Festival at the end of February / early March which 
includes tours of the Forcing sheds.  Local restaurants offer Rhubarb 
themed food.  From a foodies point of view we see Rhubarb as a sweet - 
forced rhubarb cut into chunks, placed in a non aluminium pan, add the 
juice of an orange, cover and bring to the boil, remove from heat and 
allow to stand. The stalks will be tender.   Last February I went on a 
tour of the sheds which was enlightening.  You could hear the leaves pop 
as the broke through their casing.  The sheds are mystical due to these 
popping sounds and the fact that the rhubarb is harvested by candle 
light, so as not to adversely affect the colour of the stems. After the 
tour I went to the pub across the road and had pigeon breast cooked in 
Rhubarb, followed by rhubarb crumble and custard.  Delicious.
On a personal level, I have 17 cultivars growing in large pots.  I have 
to say that when eating green rhubarb, prior to obtaining my collection 
I would not have acknowledged the variation of types and flavour.  Now 
having my own mini collection there are definite distinct flavour 
characters between them.
Regards
Clifford Cain
Bawtry, Doncaster, South Yorkshire, UK