Nice composition and I notice only that you've made a small error in drafting the door. It seems to tilt to the left a bit. Otherwise, doesn't the painting look wispy and unfinished? Well, that's the problem: it's an underpainting now, it just need more layers. Notice that the red flowers are single "smudges" and the green around them one thin layer. The branches are a single thin layer of brown. The door has some nuance in different blue hues which is good but the darks are just black lines. You did ask about shadow treatment and you've handled that well IMO as you haven't made it dark/black which is the most common error. OK, so I argue you need more layers. Here's a illustration.
See how the artist has created a fuller look just because he's kept at it. There's nice balance between the hedge, which is gesturally treated and the door which gets more detail. This artist probably had an underpainting like yours and added more nuance and rubbed out some lines with a scrubber brush.
If you're an insane master, you can end up with a watercolor like this.
It sold for $260,000. The vast, vast majority of us artists will never approach work like this, especially with watercolor, but it's nice to see how far an expert can take it.