On 16-count fabric and stitching ‘over one’ the completed pattern will be 10 1/2 inches wide x 7 1/4 inches high. Add 2- 3 inches extra fabric on each side for final mounting and framing. I like 3 inches more each side for ‘wiggle room’ for your framer.

And the final product won’t be too small for reading? I was thinking about some savings for the framing.

Seeing that the writing is well within the tulips, no problems seeing it. I prefer 16 count because I cannot see smaller fabric (higher numbers, like 18, 25, 32, 36 or 40 count). If you do add 3 inch margins to all four sides, your starting fabric in 16 count should be 16.5 inches by 13.25 inches. Two inch margins should be 14.5 inches by 11.25 inches. These would be the minimum size for doing this pattern. You might want to begin a conversation with your framer about how big of a margin he prefers for framing cross stitch.
I use two framers. One is my framer that we loved, as he helped us with choices and also with frame styles, etc. The frame company he was with went out of business, so he is at Michaels and is miserable there. The other is a fellow who frames for and art store and framed for me occasionally. He can frame with just a very tiny margin. It is always best to keep your framer happy!

Thank you. I just saw this today. I think I can work on 16 ok. I’m with you on the 18 and higher. We don’t have a lot of choices of framers in my area, but Michaels has been doing a good job for me on my last couple of jobs. I hate that cross stitch shops and framers who know what they are doing on stitchwork have disappeared. We had a shop locally that always had so many patterns, classes, and supplies, it was great. Just don’t find anything like that anymore.

Would you still use 3 strands on 16-count? And a #24 needle for 2 or 3 strands?

Do a ‘practice stitch” on the edge of your material - stitch 5-8 complete cross stitches with 3 strands of floss; then stitch 5-8 complete cross stitches with 2 strands of floss. Look at both sets of practice stitches to determine which has the best fabric coverage you like.
As for needle size, I read somewhere a LONG TIME AGO, that the needle size should be just big enough to easily go through the fabric hole smoothly but not so big that it causes the fabric threads to be forced out of shape.
No cross Stitch police here; I use a 28-count needle (Bohin) on 25 and 28-count fabric