Hi
I have checked the Hana-fuda divination site I mentioned before.
The webmaster of the site is a Japanese woman, who says she inherited the method from her late father (and he did from his parent.) Unfortunately the information she gives on the site is quite fragmentary, so it is hard to know her whole method.
http://tower8.jp/hanafuda/
It seems that main meanings of each plant are as follows (maybe inaccurate):
JAN(pine)--"MEN"
FEB(plum)--"FAMILY"
MAR(cherry)--"WOMEN"
APRIL(wisteria)--"RELATIONSHIPS"
MAY(iris)--"PERSONALITIES"
JUN(peony)--"SOCIAL MATTERS"
JUL(clover)--"HEALTH"
AUG(pampas)--"HAPPINESS"
SEP(chrysanthemum)--"TROUBLES"
OCT(maple)--"WORK"
NOV(willow)--"CHANGES"
DEC(paulownia)--"MONEY"
And seemingly, high-ranked cards have good meanings and low-ranked cards have bad meanings in general. For example, she says the "BOUZU with the full moon" card has the best meaning of 48 cards.
Hope this helps. (Note again I may be wrong!)
Kenji