just mix it all together

mixing means just that, mixing it together, like baking a cake or something. I don't know if play sand is silica sand, but silica sand is what you need if you are using sand. I have personally never used sand, but a lot of people do with success. I have a lot of sand outside, but since I don't know if it is silica or not, I am afraid to use it.

Sounds like you've been shopping at either Lowes or Home Depot. I've been asking a guy a contractor's desk about the various sands that are available. All Purpose sand is washed, but he doesn't know if it was with water or an additive. It was also the cheapest ($2.87 / 50 lb bag.) It is also what I most recently bought and used and have tried to rinse thoroughly in a bucket. I think I might try a burlap sack the next time. Then there is Play Sand (Building Materials Department, 50 lbs., $3.27 and washed). There is also silica sand, called commercial grade, 50 lbs., $4.34. There is also "tube Sand", which is the same as All Purpose Sand, only packaged in a tube shape and 60 lbs., $2.98. So there are a few options and all may be purchased at the same garden center.

The peat is fine. Sounds like you bought a bale of it (2.5 or 3.8 cubic ft.?) Was it Lambert or Schultz or Nirom brand? Hopefully it wasn't Scott's brand, because it has fertilizers in it.

It would also be a good idea to buy a $4 bag of dried LFS (Long Fibred Sphagnum moss) and put a layer of that on top of the sand & peat mix.

May I ask what sundews you purchased? Some are good for outdoors and many are really best on a window sill. Can you tell if it is D. spatulata or D. adelae?

Here are pics that might be helpful:

{{gwi:428435}} (D. adelae)

{{gwi:548173}}(D. spatulata)

50:50 mix, as suggested earlier is just fine!