|Click the picture for link to "Thingiverse"|
I was thinking of how a person might lash the pole to the railing in the most secure way when I discovered there actually is a product designed to do exactly this. The page says that it holds the umbrella steady as a rock, is simple to adjust or move, and is non-scratching... although, I don't know if it is actually for sale or at the invention stage. It looks like an invention website and there is no price that I can see.
And further, for a homemade solution, look at what this fellow did over at the All-Purpose Flower Blog. He attached two PVC tubes to the railing so that the umbrella could be moved into different places on his balcony. What a great idea. I like that very much!
|Click the pictures for link to "All-Purpose Flower"|
With an umbrella on my railing I could have much more control over the heat on the deck, protecting my plants from the worst of it anyway, while also making it more pleasant to sit out there at the same time.