You can feed one more time this week. Knockouts don't have too many blind shoot. (stem without bloom) .

Have you had much summer rain? I don't apply granular fertilizer after Fourth of July because northern VA only receives hit or miss thundershowers in July/August and the soil dries out despite my irrigation. We haven't had any hurricanes/tropical storms and its pretty dry out there. The fertilizer that I applied earlier in the season is still mostly in the soil waiting for rain. If you have summer rain your mileage may vary.

The "false bud" statement is nonsense. Most modern roses make new growth that is reddish and that will bloom.

I am in your zone and I keep fertilizing into the fall if I am using mostly "fast" or soluble nitrogen. I will fertilize around mid- September so the fertilizer runs out about the time the roses will naturally slow down. I have been doing this successfully for decades. IMO it has no effect on winter hardiness of the older canes, and it does increase fall bloom. If there is a little more new growth to be nipped by frost in mid to late November, that does not hurt the plant.

If you have made several applications of organic fertilizer during the season, there will be enough slow nitrogen in the soil, and late applications would not be helpful.

This post was edited by michaelg on Tue, Aug 19, 14 at 10:12

I fertilize (this year it happens to be Miracle Grow because that was on sale when I needed some) right up to first frost. Whether you fertilize or not they will continue to grow as long as weather conditions permit. I prefer mine to go into dormancy well fed and not having used up all their energy continuing to grow even though I stopped feeding them and would prefer them to stop growing. They have minds of their own. I've found that all this business about stopping dead heading and feeding them will some how tell them to go dormant is a bunch of hooey. As long as there is sun and water and the temps are warm enough they keep right on growing no matter what I do.

Seil is correct--you cannot make repeat-blooming roses stop growing. They are naturally evergreen and ever-blooming, and will not stop until they are bludgeoned by a hard freeze. However, when night temperatures fall into the 40s, they will start toughening up for winter, insofar as they are capable.

Most once-blooming roses are deciduous and will drop leaves in response to the days growing short.

In neither case can the gardener control these processes. The old theories about this are not true.

Thanks to all for your suggestions.
Based on these recommendations, I plan to continue my regular feeding regimen into early October.