Do I need to quilt this?
 

I just finished a quilt that is one piece of fabric on the front (cotton/poly blend) and fleece backing. Since there is no batting in the middle to shift, do I need to quilt this?

I would to hold the two together.

I've made this type of quilt as a baby quilt and quilted it. I was afraid the 2 pieces would shift in the wash. I did minimal quilting with my walking foot and decorative stitches.

I totally agree. You don't want the possibility of it sagging.

Yes, use a walking foot and a simple design to speed it up.

I would want to keep the two layers together so it won't start shifting and sagging.

Maybe just a quick cross hatch would work. It does not need to be too closely quilted

If you don't want to quilt it, you could tie it in a few places.

Years ago I put 2 fleece fabrics together and then added what I guess you would call "hash tags" in various areas to keep the 2 layers from shifting. I just used what ever little design was on my machine such as a heart or diamond and it seemed to work as these fleece blankets are still being used and have been washed un told number of times.

I concur, just simple with the walking foot to keep from shifting.

I would either do simple quilting or "tie" it with an embroidery pattern at intervals. I used an airplane design for my grandson's quilt and he loved it.

I don't think you have to quilt the whole thing to keep the layers together. I made a summer quilt and when the two fabrics were layered and done.....to the point that yours is......what I did was mark off 10 or 12 spots on the quilt and using my sewing machine and a matching thread, I just did a stitch-in-place 5 or 6 times (I used my quilting foot with the feed dogs down), then moved onto the next marked spot. It was just enough to hold the 2 layers....not enough to define a design.

I've used a decorative stitch. One that I hopped around and placed in various areas to hold the two pieces together.

It depends on the size. If you made a very small baby quilt, maybe not. But, anything larger needs something to hold it together even if it is only knotted at strategic points. This keeps the pieces lined up - especially after washing. But, it does not need allover quilting. Look at it and decide on something simple (STID or a diagonal line). You can always add more detail later.

I would to hold the two fabrics together.