To create a wind effect on plants using physics in Spine, you can utilize the physics constraints feature to simulate wind and gravity. You can set the wind and gravity values directly on the physics constraints to achieve the desired effect. By keying these values, you can modulate them to create a dynamic wind effect. Additionally, you can write code at runtime to control the wind, providing a more random and natural behavior. For a more organic feel, consider slightly varying the apex of your curves so that each bone has different values and spacing, which can enhance the realism of the wind effect.
For more detailed guidance, you might find it helpful to watch tutorials or explore examples of similar effects, such as the windmill tutorial or the Wave principle video.