Yes, you can. It will not compromize your blooms. Gallicas bloom on a new growth, that is coming from the last year growth. So if you shorten your canes, for example 1/3 you will promote more side growth and as a result more blooms, not less. Additional benefit is that your bush will support its blooms, you will escape seeing your blooms in the mud after the rain. This is an old wifes tale that old European oncebloomers should be pruned only after the bloom. You can't see the structure of a rose when it is covered with leaves. So after the bloom it is a good time to shape your bush, but major pruning is better if it is done in late fall or winter. I don't think it is too late now. I just pruned several of my gallicas, that escaped winter pruning somehow, last week. I do my pruning this way for the last 20 years and my gallicas always bloom like crazy.
Olga

If the flowers are coming from old wood shortening the old wood cannot increase the amount of bloom over what would have been produced otherwise. Of course you can get away with it because the remaining 2/3 of the cane will still have some bloom. Likewise pegging increases flowering because bloom tends to be concentrated at the highest points, arched over canes will have a longer section that is above the rest than vertical canes.

Bboy, when you cut the cane ends, you get more NEW side shoots and they will bloom. More side shoots, more blooms. Flowers are formed on the NEW wood that is coming from old wood. Just try and you will set it yourself.

Olga is absolutely right-it is the buds on the old wood that have to go through cold in order to bloom. Many those buds dont break(produce laterals that bloom)unless the more dominant bud on top is removed(or pulled down in pegging) We have all experienced our over-loaded gallica flowers laying down into the dirt..pruning back helps with this. Not all Gallicas appreciate being pruned but most of them like it just fine.

patricia

IMO using that terminology is an over-simplified and uninformative description of the issue. We don't prune just cuz. We prune to train. Pruning generates growth. Timing growth is everything with once bloomers.

Blooming on old wood means that the basal and lateral canes produced last year (or earlier) have the capacity to generate bloom - -from all laterals they produce-- and that neither basals nor laterals produced after the flush will not flower because the plant already bloomed for the year. New laterals from old basals will bloom if they grow in time for the annual flush. But if the plant blooms before it produces laterals, then it only blooms on last year's "wood". Furthermore, this year's basals, produced before this year's flush, are inconsistent in bloom the same year. Some will, but most will not. In my limited experience (only a few in my garden), Old Europeans are in the "will not" group.

Too much pruning in the spring sometimes generates a bunch of new basal growth before the spring flush, and that growth won't be mature enough to bloom this year. The lush new growth swamps the older, flowering wood. So that's another factor to consider in pruning in the spring.

Those of us who live in hot climates need to juggle factors like the heat and drought stress our plants will be under if we prune after the flush. It just feels wrong to prune a plant in 100 degree temperatures.

This is the knowledge you need to apply to your pruning. Several classes of roses are implicated, and they don't all grow alike everywhere. Old Europeans don't grow exactly like once blooming climbers.

I have a cold, dry spring, so my Old European roses bloom on laterals before they put on substantial new basal growth. With ramblers, there have been exceptional years, where if I pruned too hard in the winter and if the spring was wet and mild, I promoted a lot of lush green growth before the flush, obscuring the bloom. As for summer pruning, I don't do much. But if the weather accommodates and if I notice older unproductive wood that I missed pruning out, I will definitely remove it to channel the plant's growth into productive new canes. I training roses year round in moderation.

Berndoodle-great description. I guess I just did the short version. We can have extreemly long bloom on Gallicas here-well into July...I assume because of our cold nights. Buds apparently must accumulate a certain number of chill hours in order to make blooms but I must say I have been paying insufficint attention to who is doing what when. Like you I prune to shape all during the year but I certainly dont expect any more bloom after the bloom season although I do have a few Gallicas that will throw the occasional flower. I wonder how many chill hours it takes? I tried to do some research on that once but dont have access to those University sites you have to pay for-our benighted county doesn't even have county libraries. Didn't seem to be much out there anyway..now fruit trees....There must be an ideal temperature for a certain period of time. I know there are some who think the chill thing is junk but it does account for why so many ogr's dont bloom in places with no winter. It would be the build up or break down of some plant hormone plus storage of enough carbs. In any case a little judicious shaping this time of the year(we are barely breaking bud)shouldn't hurt anything.

patricia

Here, gallicas bloom late...but they don't bloom long because it gets so darned hot by mid-June that they fry before noon. If I lived in a climate where spring rain was extensive, they'd probably do a lot better. They seem to be a water-loving group.

I was not aware that chill during bloom was a factor, not that it surprises me. I do know that winter chill hours are required for spring bloom. I happen to live in a mild climate that usually has ample winter chill hours - depending on the methodology used, from 925 hr (in a mild year like this year) to 1235 chill hours (in a cold year) between 32 and 45. I have no problem with once-bloomers wanting to bloom. The problem is timing, because they tend to be late. They are often ruined if they wait until mid-June, when our daytime temperatures can reach 100â for days on end with not a bit of rain. The Mediterranean climate is not great for gallicas.

Now I'm confused..sorry..and I know this is a somewhat old thread. I have a CDM that I planted last spring. I'm in Zone 4 and this rose is now huge (probably tripled in size in a year) There are probably 30 arching green 'canes' . Even last summer I experienced the 'blooms in the mud' referenced above.

So, in my climate, can I prune now? (they're already touching the ground) If I do will I sacrifice blooms? Will it make this a better blooming rose next year? Truthfully, if it continues to get bigger and bigger I'll have to move it anyway. Is there a way to keep this rose small-ish? Like 3 ft or so high and wide? Oh and last summer I had only a single bloom..