“The old saying is that you cut your roses back before President’s Day and your azaleas before the Fourth of July” was cited in 2015. It’s not certain when the two gardening adages first originated.
 
“Rose bushes shouldn’t be pruned until February. The best time to prune is between Valentine’s Day and the first of spring because the canes of bushes pruned in the fall will likely be injured during harsh winter weather” was cited in a 1986 newspaper. “Prune roses no sooner than President’s day is the traditional saying here (Portland, Oregon—ed.), but, I would personally wait a little longer because we usually get another freeze after that time” was cited in 1999.
 
“Major pruning of azaleas is done following bloom or in any event before the Fourth of July” was cited in a 1987 newspaper.
 
     
Google News Archive
25 February 1986, Sumter (SC) Daily Item, “Springlike weather benefits small grains” by Rowland P. Alston, pg. 5C, col. 2:
Rose bushes shouldn’t be pruned until February. The best time to prune is between Valentine’s Day and the first of spring because the canes of bushes pruned in the fall will likely be injured during harsh winter weather.
 
Google News Archive
25 June 1987, Reading (PA) Eagle, “Moisture, sun are critical to building strong azaleas” by Evin McDonald (King Features Syndicate), pg. 38, col. 1:
Major pruning of azaleas is done following bloom or in any event before the Fourth of July. This is the time to remove dead wood and direct overall shaping of the branch framework or super-structure. For azaleas that are by nature loose and dry, no further pruning is needed.
 
Google Groups: rec.gardens.roses
When to prune: Zone 8a (Portland, Oregon)
Siemsen
1/26/99
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Prune roses no sooner than President’s day is the traditional saying here, but, I would personally wait a little longer because we usually get another freeze after that time.
 
Google News Archive
31 January 1999, Victoria (TX) Advocate, “Garden spot: Warm weather gets gardeners antsy” by Beverly Arnold, pg. 6D, col. 3:
Roses should be pruned on Valentine’s Day Feb. 14.
       
Google Groups: rec.gardens.roses
cut back rose’s
Radika Kesavan
11/9/01
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Over here, most people normally get their pruning started around Thanksgiving and finish by Christmas, depending on the year and the number of roses. I think the local paper’s gardening column used to advice to get started around Presidents’ Day weekend, since officially, that is when the last frost is supposed to be over. Personally, I think that is way too late for us since all sorts of new growth is already started on roses and grapes by then.
   
Google Groups: rec.gardens.roses
Is it time to prune in zone 9?
Radika Kesavan
12/23/02
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If you wait till later, even in colder years than this El Nino one, new growth will start making it a difficult choice as it would be to sacrifice part of the spring flush. Around here, the local papers (SJ Mercury News, for example) used to say that Presidents’ Day is the last day for frost and to wait until that time to prune your roses. In my experience, that is way too late for my roses, and also, as tough as some winters here have been dipping to single digits and all that in these last fourteen years that I have been here, I have never seen late season frost that was so cold as to kill roses. Avocado, citrus, agapanthus, hibiscus - ye, they all can get killed by cold winters here, but not roses .... so ...
 
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BC Nursery
‏@bcnursery
Presidents Day is a handy way to remember when to prune roses. Cut hybrid teas back to knee height. Shrub roses and old garden roses…
10:18 AM - 17 Feb 2010
 
Twitter
MasterGardeners
‏@therealdirt
@katiekeenan Here’s a good way to remember when to prune roses: anytime after President’s day.
12:58 PM - 9 Feb 2011
 
Twitter
Landscape Design PDX
‏@Winterbloomer
Presidents Day Gardening Tip - Great time to prune roses/plant new ones. http://www.heirloomroses.com  = best place to purchase self-root roses.
6:00 PM - 17 Feb 2012
 
The News Star
Don’t wait to prune azaleas
2:28 PM, May 16, 2013
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Azaleas respond well to pruning. Once a stem is cut, a growth response is stimulated, usually resulting in several new stems arising a few inches below the cut. These new stems will grow during the early summer, eventually setting flower buds in July. Therefore, pruning after early July may reduce next year’s flower production. The fourth of July is a good benchmark to remember. Always finish pruning by July 4th every year to maximize flower production next spring.
 
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Love & Carrots
‏@LoveNCarrotsDC
Pruning your azaleas should happen after bloom but before Fourth of July!  http://ow.ly/lsvQB
7:45 AM - 28 May 2013
 
DeSoto Times-Tribune (Hernando, MS)
Azaleas trimmed at courthouse
By ROBERT LEE LONG Community Editor Jun 24, 2015
Just as everyone needs a trip to the barber’s chair every now and then, the large, overgrown azalea bushes on the north side of the DeSoto County Courthouse are getting a trim, thanks to local landscape architect Michael Hatcher.
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“The whole intent is to get out in front of any problems,” Hatcher said. “These old Southern azaleas need to be cut back. The old saying is that you cut your roses back before President’s Day and your azaleas before the Fourth of July.”