While there are a number of flowering plants that have green flowers, there are few that have a true turquoise color. The genus Lachenalia has more than 100 species, most of which are found in the Cape Province of South Africa, but only Lachenalia viridiflora has the exquisite true turquoise color. It blooms earlier than most of the other species, coming into bloom here at Telos before Christmas, and continuing into January.
Lachenalias are in the Family Hyacinthaceae, and are easy to grow. Like most other South Africans they come into growth in the fall when the rains arrive, grow throughout the winter and go dormant in the summer when they must be kept dry. There is an amazing range of color, and many are also scented. They do need good light, but can be grown on a windowsill in bright light but they must have cool temperatures. A porch or unheated sunroom is ideal.
I have posted before on Lachenalia, and you can find that post here: https://thebulbmaven.typepad.com/the_bulb_maven/2009/03/lachenalia.html