Perennial spikey green plants are a popular garden choice because they return every year, make distinct accents and borders, and tend to be relatively low-maintenance, allowing you more time to baby your annuals and focus on other areas of your yard. However, some exotic-looking plants can grow quite tall or become far too spikey to prune or garden around. Knowing exactly the right perennial for your garden will help you create a yard that fits your style and maintenance capabilities.
Eryngium yuccifolium is a small, compact green plant with narrow, bright green leaves that have a shape reminiscent of a chainsaw. Gardeners often use these plants in borders since they retain their shape year after year and do not tend to encroach on other grasses or flowers. In addition, they are not so spikey as to make gardening and weeding around them impossible. When Eryngium yuccifolium is about a year old, it will sprout tall, pale stalks with thistle-shaped balls on the tips. These balls will release seeds if you don't remove them. According to American Beauties Native Plants, this plant is deer-resistant when mature and provides nectar for several species of adult butterflies.
Phormium, also called New Zealand flax, will grow in many places other than New Zealand. Most species of phormium are fairly hardy and have green leaves. However, a number of colorful hybrids have maroon and bronze leaves that do not tolerate extreme cold or extreme heat, so your local climate should be suitable for a hybrid form of the plant. Phormium can grow upright to a height of several feet. If you want more relaxed spikes, then select a slightly-arching or arching form of the plant instead.
Veronicastrum virginicum is native to Mississippi, where these plants typically reach three to seven feet in height when mature and in full bloom. The leaves are long, green and lance-shaped, and the blooms, which tend to be white or pale blue, circle tall stalks so that the flowers also add to the pointy effect. The plants bloom from late spring into the summer, and the leaves remain in tact for most of the year. This plant can grow in sun or shade, but if you grow it in the shade, you may need to stake some of the leaves since they will get longer in shade than in sun.
The Lady Bird Johnson Wildflower Center attributes this plant's common name, culver root, as an honor to a doctor who prescribed it as a laxative. However, you should not use any laxative, natural or otherwise, without first consulting a physician.