Plants With Ornamental Spikes

Spiky Succulents

• Nothing screams "spikes" like agave (Agave spp.). These spiky succulents grow in U.S. Department of Agriculture plant hardiness zones 6 through 11, depending on species, and offer varying heights from around 1 foot to 12 feet tall. Weber's agave (Agave weberi) is hardy in USDA zones 8 through 11 and has deep blue-green foliage that reaches up to 5 feet tall. For an interesting look, consider octopus agave (Agave vilmoriniana), which grows in USDA zones 9 through 11. The gray-green foliage twists in different directions, creating the look of octopus tentacles. Like agaves, yuccas (Yucca spp. and Hesperaloe spp.) are the epitome of spikes. While most varieties are a bluish-green, some are green and a few are variegated. Members of this genus vary greatly in shape and size: a few are around 1 foot tall and others are tree-like. For a specimen, consider the trunked, 5-foot-tall Sapphire Skies beaked blue yucca (Yucca rostrata "Sapphire Skies"), which grows in USDA zones 5 through 11. Adams needle (Yucca filamentosa), which grows in USDA zones 4 through 9, has 3-foot spiky, blue-green foliage that is highlighted by 5-foot creamy-white spires of flowers throughout the summer.

Flower Spikes

• Delphinium elatum, which is hardy in U.S. Department of Agriculture plant hardiness zones 2 through 7, is a parent species to many of the hybrids available today. Reaching 3 to 6 feet tall and offering racemes of flowers in blue, pink, purple and white, this summertime perennial is a spiky masterpiece when planted in masses. Baneberry (Actaea spp.) grows in USDA zones 3 through 9, depending on species, and offers tall spikes of fluffy white flowers. The foliage of some baneberry cultivars is deep blackish-purple, offering even more intrigue to your garden. Cardinal flowers (Lobelia spp.) come in either red (Lobelia cardinalis), which is hardy in USDA hardiness zones 2 through 8, or sapphire-blue (Lobelia siphilitica), hardy in USDA zones 4 through 8. Both bear their colorful flowers from summer through early autumn.

Graceful Grasses

• Decorative spiky grasses are common accents in container plantings, but when placed in a bed, they can create a graceful flow of spikes and spiky racemes during even the gentlest of breezes. "Karl Foerster's" (Calamagrostis x acutiflora "Karl Foerster) grows in USDA zones 4 through 10 and offers white, spiked flower tops atop the upright, green blades. For spiky color, consider "Shenandoah" red switchgrass (Panicum virgatum "Shenandoah"). Deep purplish-red blades intertwine among the green blades in 3- to 6-foot-tall clumps.

Prickly Plants

• Spiky and prickly go hand-in-hand and, as such, at least one prickly plant should make your shortlist of spiky plants. Sea hollies ( Eryngium planum), which grow in USDA zones 5 through 9, offer prickly, thistle-like blue flowers surrounded by spiky collars. Other members of Eryngium offer different colors and looks. Bear's breeches has an equally prickly appearance, although the 3-foot-tall white, purple and green flowers and bracts offer a focal point that will captivate the eye. Bear's breeches are also evergreen, and their glossy, large leaves create winter interest in USDA zones 7 through 11.