From the Painting Guide: I like the strong graphic quality of these flower portraits and think you've succeeded in creating backgrounds that are interesting while allowing the focus to remain on the flower.

Things to consider:
• Shadows: The amaryllis doesn't need a shadow (think of it being as in diffused light). The shadow on the bird of paradise makes it feel as if the flower is right up against the wall. Don't these flowers come out of the centre of a bunch of leaves?
• Composition: The potplant of the amaryllis is a distraction and should possibly be left out. There also needs to be more background at the top and on the left-hand side; it's presumably there and just got cut when the photo got cropped. The bird of paradise has two strong diagonals – one the flower, which goes across the stem, and the other in the leaf, which doesn't. Maybe there should be another, small leaf at the bottom to continue this diagonal so that your eye doesn't get pulled off the bottom of the painting so strongly.
• Getting texture: Various paint manufacturers produce texture gels or pastes which you can mix with acrylic colour. Winsor & Newton (used as an example only because I have a leaflet from them to hand) produce "fine, medium, and coarse texture gel", "natural pumice texture gel", "natural sand texture gel", "black flint texture gel", "glass beads texture gel", and "modelling paste" which can be sanded and carved. You could also simply mix your own sand etc. into the paint, though paint manufacturers will tell you there's the risk of introducing impurities which'll influence colour stability and permanence. If you're trying to recreate a wall that's had a paint effect used on it, such as spongeing or stippling, it may be easiest use that technique on your canvas (see the decorative painting links for more info) rather than trying to reproduce it with a brush.