How about a very pale green.

I like the limey color in the print, so a subdued version of that maybe?

Do you have white furniture in mind, or other?

I like the pale blue-green in some of the leaves.

I'd pick from the main colors: pink, purple, green, and ask which she prefers. They're all great choices and this print is beautiful.

I’d stick with white walls but then paint the doors (back of bedroom door, closet door) color from the paper, or even the trim

It's hard to pick colors in a vacuum. You'd get better advice if you post photos of the room and the furniture, rugs and window coverings. If you haven't yet selected them, wait until you do--the paint color is selected last, as it's the easiest to blend with the other items.

It depends how saturated in color you want the room to feel. If you go pale ? Ben Moore Feathered Lilac.......

Either way, I hope its freash white trim, and white furniture a nice bonus as well.

In any scenario, I'd get the bedding selected so you don't paint yourself into a corner.

Bold?

Ben moore pistachio

A green or greenish brown.

https://www.benjaminmoore.com/en-us/color-overview/find-your-color/color/2029-60/pale-vista?color=2029-60&source=%2Fen-us%2Fcolor-overview%2Ffind-your-color%2Fcolor-families%2Fgre%2Fgreen

Take the wallpaper to the paint store and have them match the background of the wallpaper. It may seem "boring" but it will allow the wallpaper to shine and keep other options open like bedding, etc. Make sure it works with your trim as well, or paint the trim the same as color only in a semi-gloss finish. Love the wallpaper and it can grow with her for a while at least. Then, as she matures, you just change the wallpaper!

Thanks everyone, I like the lilac color suggested above but it may be too much with the purple rug. I'll need to get a sample to see. My daughter DEFINITELY prefers pink of all the colors in the wallpaper.... although because she is 4, I do wonder if she will outgrow that preference soon. I chose a wallpaper that I thought would work for her for a number of years, but I'm not sure about the pink wall color. I guess I can just repaint at some point! :)

I don't want the colors to be too saturated because it's a Tudor home so the windows are smaller and it's overall a bit dark. I don't want to contribute to the darkness with walls that are also very dark.

The colors I did try were shades of pink/rose that came from the wallpaper, so thanks for validating that was a good strategy.

The trim will be Simply White by Benjamin Moore.

The furniture is a chocolate color - we've had it for a while, but I think I may replace it with a white set soon to brighten up the room.

Question based on a couple of comments above: I thought we would select the bedding last since it's easier to change out and adapt to paint colors etc. But it sounds like I should pick that earlier and then find a wall color that works? I didn't realize this was the best order of operations for this process.

Thanks!

Yes. Always select hardest to find items first. There are hundreds or thousands of paint colors! Paint color last.

kindergardener girls often seem to go through a big pink phase as they have become aware of conformity, hard to say how long it will last, I grew to hate pink when I was little, but everyone is different

also, the flowers appear to me, to be a rose or raspberry red with hints of blush and pink, there seems to be more of a bluish cast to the flowers, not sure if pink is going to look clashy.

Here we are with all palette in your wallpaper, so go with any one you like, :-))

IMO white like the background on the print since next year there will be a new favorite color palette and at least you won’t need to paint all the walls. Kids change there minds about what they like on average once every 2 yrs some much more often . My Mom and Dad did our rooms white with a huge cork board on one wall for all the stuff we wanted to put up for a year like poster , tickets, photos etc. Our favorite color of the year was in bedding my Mom made and we added some pillows we liked .

I rest my case, if going pastel I’d lean towards lilac, or a very soft muted blush.