Cotentin Côté Jardins recommends these gardens which, although independant of the association, are open for visits in the Manche.  Here is a brief description with opening times, admission and directions:

• Other gardens to visit in the Manche

And, three dynamic clubs, a choice of guides to gardens of the Manche and finally nurseries and plant centres in partnership with CCJ:

• Clubs and Associations
• Nurseries
• Books on gardens