Our Clematis doesn't flower.

We have several Clematis in the garden. Some in the ground and some in planters.
This one



which my wife believes in Montana "Alba" has never flowered. It looks healthy but despite this being its second summer we have never had so much as a flower bud from it. Can anyone offer any advice? What could we be doing wrong?

 

A couple of possibilities....it might be a seedling rather than a plant produced from a cutting, so shy to flower. As Montanas are early-flowerers, could be that late-ish frosts are killing off the buds? Give it a good dose of blood, fish and bone or a high-potassium (K in the NPK) feed and see what happens next year

 

From the photo the spot looks dry and sunny but Clematis likes its roots to be shaded. I don't know if that's the cause but it's a thought.

 

That was the CEO's thought so we have put slate chips around the base.
@noisette47 We didn't get much in the way of frost for most of the winter being so close to the coast. Whether it is a seedling or a cutting I have no idea. We bought it online from either Taylors or Thorncroft.
The boss swears by Tomorite.

 

Both those nurseries are reputable, so that's that theory out the window Perhaps it just needs more time than most to settle in? Tomorite should do the trick!

 

this flowers on last years growth sooooo did you give a haircut over the winter as you may have cut off all the flowering shoots buds

can you take A close up of the leaf please ....

we also had a very dry april which woudnt of helped it looks like the whole are is thirsty

 

It has not been pruned since it was planted. I have put loads of water into the ground around it. First with the hose and recently with the sprinkler.
Here are the leaves.

 

Seems someone else in the forum had the same problem with Alba -
Clematis Montana Alba

Looking at your photo above the leaves look so lush and healthy, makes us think its not flowering because its too happy growing leaves on a high nitrogen feed, but that would not be the case as you say its fed on Tomorite ??

 

looking very healthy

 

My wife called me out to take a look at the Clematis this afternoon and I believe it is starting to flower. Better late than never.