“Don’t prune in May or June” (gardening adage)

A popular gardening adage rhymes “prune” and “June.” “Don’t Prune in May or June” was cited in print in 1980. “If it flowers before June, don’t prune” was cited in 2000. A comment was posted to the Internet in 2002:
 
“About 14 years ago I coined the old Hampshire saw about pruning clematis: if it flowers before June, do not prune.”
 
“Don’t Prune in April, May and June” was cited in 2003. “Remember the old adage for oaks, ‘April, May and June do not prune!’” was cited in 2015.
 
   
Google Books
Overstory: Minnesota’s Urban Forestry Newsletter
Volumes 1-12
1980
Pg. 69:
People in prime oak wilt areas again see billboards saying “Don’t Prune in May or June” thanks to a cooperative agreement between Minnesota Department of Agriculture and Naegele Outdoor Advertising.
   
Google Books
Michigan Forest Health Report
Department of Natural Resources, Forest Management Division
1991
Pg. 3:
This “overland transmission” of oak wilt occurs primarily in May and June. Thus, a popular oak wilt prevention slogan is, “Don’t prune in May or June!”
       
Google Groups: uk.rec.gardening
inherited Clematis
Rachel
8/29/00
(...)
A good rule of thumb for Mystery Clematis is ‘if it flowers before June, don’t prune’ (if it flowers after, prune hard).  It’s a useful adage, but not accurate a hundred percent of the time. In the North of England I take the longest day as the cut off point - no pun intended:-).
 
Google Books
Shade Tree Wilt Diseases:
Proceedings from Wilt Diseases of Shade Trees: a National Conference August 25-28, 1999
Edited by Cynthia L. Ash
St. Paul, MN: APS Press
2001
Pg. 247:
Their message, “Do not prune in May and June,” is a great slogan that has come to be understood by a lot of citizens who know nothing more about forest pathology than what is contained in that one simple rhyme.
 
Google Groups: rec.arts.sf.composition
Week and a half of…
jf
3/16/02
“Elizabeth Shack” <

> Can I steal that?  I’m not sure what I want it for yet.
You may quote it without attribution from now till next muck spreading and welcome.

JF
About 14 years ago I coined the old Hampshire saw about pruning clematis: if it flowers before June, do not prune*. A couple of years ago I heard it used by an expert on the radio. One day I hope I’ll hear someone call it an old Hampshire saw.
 
*For the Northern Hemisphere. For our NZ readers: if it flowers before December, not to prune you must remember.
   
Google Books
Forest Insect and Disease Newsletter
Minnesota Department of Natural Resources, Division of Forestry
2003
Pg. 1995:
The slogan ‘Don’t Prune in April, May and June’ was advertised across the state and soon most Minnesota residents.
 
Twitter
Annemiek Cox
‏@Annemiek_Cox
Nu Clematis snoeien? Ezelsbruggetje: if it flowers before June, don’t prune
2:36 PM - 9 Mar 2012
 
Twitter
john stavinoha
‏@jstavi
“@TXForestService: Central Texas trees at risk for deadly oak wilt disease: http://bit.ly/1039NTz ”
Don’t prune February to June!
8:24 AM - 1 May 2013
 
Twitter
Christine Bottomley
‏@ChrissyBotto
-“If it blooms before June don’t prune “-says monty but it’s bloomed and now looks sad on my garden fence #clematis
3:56 AM - 18 May 2014
     
Mille Lacs Messenger (Isle, MN)
It’s spring – let gardening begin
Posted: Saturday, May 2, 2015 6:00 am
by Janice Hasselius Master Gardener
(...)
Oaks can still be pruned now. Remember the old adage for oaks, “April, May and June do not prune!” The reason for this is to not spread the oak wilt disease which is active during this time frame.