Flowers on your dress for a garden wedding—I like that and would likely continue on that theme.
The skin-colored or metallic shoes mentioned above would make your legs look longer, which many people want. Another route you could take would be to pick up on the red or green for the shoes, then continue the theme with accessories either in those colors or in the shape of plants, maybe like this headband. https://www.sallybeauty.com/ha.....38;start=1
Make sure that what you wear is comfortable for the occasion. Go for flats or, if you want heels, then platforms/wedges (so the bottom of the shoe is flat). There are more likely to be bugs than at an indoor event, so you might want a very light wrap, like voile in the same navy as the dress.
Once you’ve got your outfit on, relax and have a great time at the wedding!