Verbena is a tricky plant to grow for me. I don't know why, but I always feel the need to buy them when they are on sale. I follow the directions and they still die. The only one that I've had success with is the sand pink verbena. It loves sun and performs well here in Tucson. At times, it can get a bit leggy and isn't as nice a groundcover as other verbena. I put this plant with other groundcovers and it looks great. It is said to be endangered along the Pacific Coast, but here it is sold at the local garden centers. My recommendation is to forget the other verbenas and try this little guy out. It has beautiful pink flowers and will add that color pop in your garden.
Here's a little blurb on this native plant to our deserts.....
"Pink or beach sand verbena is a prostrate, somewhat succulent perennial with few to many slender, glabrous to glandular-hairy stems and opposite, ovate to diamond-shaped leaves on stems as long as the leaf blades. A member of the coastal strand plant community, sand verbena is typically found on beaches and sand dunes near the coast from San Diego Co. north to Yuma, AZ blooming throughout most of the year. The flowers are in clusters subtended by 5-8 rose-colored lanceolate bracts. There are no petals, and the five calyx lobes are in turn cleft into two lobes, making it appear that the plant has ten petals. The limb of the perianth is rose to bright magenta with a central whitish spot and the tube is green or red and glandular-pubescent. The one pistil and three stamens are included within the tube. A. umbellulata hybridizes with several other species of Abronia, including maritima." End of article.
Sand-verbena likes full sun, and sandy soil. Sand-verbena has gray foliage with pinkish purple flowers, and the flowers are fragrant. It does not tolerate weeds and needs bare ground. They require little to no care, but do water once a week during the hot months if monsoon rains seem to be lacking.