The date was decided at a high-level meeting between Chief Minister Vijay Bahuguna and office bearers of the Kedarnath Mandir Samiti, which oversees the revered shrine.
A senior official said Sep 11 was auspicious as "Naag Panchami" would be observed that day.
The stars would in the right conjunction to restart the prayers that were halted after flash floods ravaged the area June 16.
The floods occurred at a time when the Char Dham pilgrimage when tens of thousands of believers make it to Kedarnath and three other ancient temples in the hills was at its peak.
Several feet of slush and rubble collected inside the sanctum sanctorum of the temple, killing hundreds in the region.
Many more died elsewhere in the hills of Uttarakhand because of flash foods and cloudburst.
More than 5,000 remain missing.
Housing the 11th "Jyotirlinga" of the 12 fabled Shiva shrines that are known as Jyotirlingas, the temple is said to be over a thousand years old.
But although the region was ravaged, the temple stood intact, by and large.
The 14-km walking stretch between Kedarnath and Gaurikund, the base camp for the pilgrims, still remains shattered and unapproachable.
Office bearers of the shrine said that by the time puja starts, the rubble that has collected will be cleared.
The chief minister had earlier announced that the 'puja' would start at the Kedarnath shrine in the ongoing holy month of "Saawan".
Inclement weather caused that date to be put off.
Officials said that though the temple premises would be cleared, the track from Gaurikund may take longer to put back on track. And pilgrimage to the shrine would not be possible for another year or two.