I think I know what you are getting at Sue.
I read a very old farming manual once that used a system like that. It was more concerned with how long you could sit your bare bum on the ground and be comfortable than on the calendar date.
They also mentioned not planting before some of the trees were in leaf or some of the flowers out.
They were quite specific about the flowers.

I have seen similar ideas expressed in some mushroom manuals, but I have no word that fits.

"Planting by the signs" has been taken already by the Astrologists for planting by the moon and by the zodiac.
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OK, A Phenological planting guide?

Phenology comes close but I think it might not be catchy enough.
http://en.wikipedia.org/wiki/Phenology

Maybe we can put some makeup on it and tart it up a bit.
Phenochrony
Phenosynchronic
Phenosynchratic
Phenosynchristic
Phenochroidal
Phenomodal

I give up.

Good luck Sue. I know it can be really hard to coin a new word.