Gardeners, Gardeners flowers are carefully tended. the correct form of the plural noun

You need to make gardeners by adding ' at the end.

Check this site for the rules and examples of possessive nouns.

http://www.edufind.com/english/grammar/Possesive1.cfm

The correct form of the plural noun "Gardeners flowers" is "Gardeners' flowers."

The correct form of the plural noun for "gardener" is "gardeners". To form the plural of most nouns in English, we usually add an "-s" to the end of the singular noun. In this case, "gardener" becomes "gardeners" when referring to multiple individuals who work as gardeners.