How to decorate the gazebo?

Have you looked on Pinterest for ideas? Whatever you do, I'd keep it very simple. That's a beautiful area all on its own.

Can you substitute potted flowers where the others used to be?

Maybe on the left & right posts put long floral arrangements and then take them to the reception to put on the head table.

Tulle? Maybe run some flowers around the opening of the gazebo? It's a beautiful space. I wouldn't worry but so much.

I think it looks gorgeous on it's own! You could wrap some tulle or something around the gazebo posts to make it look more weding-y, but I think that would take away from the natural beauty of it.

Agree that potted plants would look very nice at the entrance, but transporting them may be an issue cause they'd be very heavy.

I'm not a fan of deco mesh for a wedding. I think flowing white fabric would be a prettier, more formal look. If you liked the idea of deco mesh because they come with the twinkling lights inside, you can add the lights behind the fabric (white cords only). The only photo I could find was a gazebo decorated with wide tulle and lights (tulle works, but not everyone is a fan).

http://www.merchantcircle.com/business/Party.Time.Designs.LLC.732-495-1154/picture/view/1477498

If you're not adding a floral spray or floral pieces to the arbor, go to your local nursery and get two potted rose bushes (or any tall, flowering plant) with a good amount of blooms, put them in white pots, and put them on either side of the gazebo opening. That's always nice because the couple can take the bushes home and plant them. It's an everlasting memento.

You could use fabric, and drape it...check out the photo attached.

I like the idea of the plants on the side, and the flowy fabric wrapped around the frame just because I do want it to be more wedding-y. Maybe I will add some flowers to the frame as well. The memento idea is beautiful as well! We could use pretty flower bushes in our house, specially as a memory of our wedding!! Thank you very much ladies!!