Spikes are the tall, narrow-flowered fillers that anchor mixed containers and border schemes. These 6-inch plants grow upright with dense flower spikes in reds, purples, whites, and bi-colors, reaching 12–18 inches by midsummer.

Plant spikes in full sun with average moisture and well-draining soil. Deadhead spent flowers to keep them blooming through frost, and they'll reward you with weeks of vertical color.