“The hardest things for me to raise in my garden are my knees” is a joke about old age and gardening. “The hardest thing to raise in my garden is my knees” was cited in print in 1997. The authorship of the jocular saying is unknown.
 
   
Google Books
Beds I Have Known:
Confessions of a Passionate Amateur Gardener
By Martha Smith
Wakefield, RI: Moyer Bell; Emeryville, CA: Distributed in North America by Publishers Group West
1997
Pg. 12:
More a commentary on the annoying limitations of growing old than of growing flowers, its caption read, “The hardest thing to raise in my garden is my knees.”
   
Google Groups: alt.humor
Wanted: Your so old jokes
Keith E. Sullivan
3/23/97
(...)
The hardest things for me to raise in my garden are my knees.
 
The Philippine Star (Mandaluyong City Philippines)
Green and Bear it with Gary Lising
By Ching M. Alano | Updated September 9, 2001 - 12:00am
(...)
Old age: The hardest thing for me to raise in my garden is my knees.
   
BreastCancer.org Discussion Boards
Sep 29, 2005 11:44am MJB wrote:
“THE HARDEST THING TO RAISE IN MY GARDEN IS MY KNEES…UNKNOWN
   
Homegrown by Cindy Hadish
The hardest thing to raise
March 12, 2008
The following post is by Master Gardener Ellen Skripsky: 
(...)
As an anonymous gardener once said, “The hardest thing to raise in my garden are my knees.” 
 
Twitter
martina‏
@362t
6:42 PM - 10 Apr 13  
The hardest thing to raise in my garden is my knees.
6:42 PM - 10 Apr 13