If you have a space in your garden to fill, and you'd like to add a cool colored plant, the flower commonly called Spiderwort is a great candidate. The real name is Tradescantia. The flower of the Spiderwort is a very cool blue. It can be good to pair with a contrasting color, like a red, to allow each color to pop.
Spiderwort will grow to be about two to three feet tall, and the three-petaled flowers will bloom all summer long. The plant grows best in moist soil, and needs to be watered regularly.