Montanas are funny things. I had one for about 10 years that never gave me many, if any, flowers, frost always seemed to occur at the wrong time, and bits of it were frequently dying back. The winter before last it froze to the ground, and I put all the above ground plant into the bin in the spring. Then new shoots came from the roots in the summer, it grew like wildfire, and this spring a plant as large as it has ever been was completely covered in flowers.