There are a number of factors here, two of which you've identified:

• a yellow color cast
• shallow depth of field, possibly with additional post-processing blur

These are important, but part of the dream-like appearance comes from the high key. Here's the histogram for the image:

which shows that all of the tones in this image are brighter than the 50% mark, with the bulk being way up in the top 20%. Nothing is even close to dark, let alone black. This brightness, especially when combined with blur or soft focus glow (not really seen in this example), tends to contribute towards a dreamy, ethereal appearance.

If we use the Levels tool to bring up the black point, stretching that same histogram across the whole range, the image looks like this:

and if we use Auto Levels to correct for the yellow cast in addition to that stretching, we get:

Both still have the blur, but are much less dream-like in appearance.

This is kind of extreme, and the high contrast now looks like an effect in its own right. The "realistic" image is somewhere in the middle.

I think it's pretty clear in looking at the adjusted images that the blur is from a shallow depth of field; the flowers are in narrow band of focus and the nearer and farther objects are blurred. This suggests that a long focal length was used, in combination with a wide aperture. It doesn't seem like post-processing blur was added, although it's possible that there's a smidge of it in the bottom front.

This also brings out what looks like corner vignetting, but that may just be the framing of foreground objects rather than either lens obstruction or a post-processing effect.