The common sunflower, plume poppy, Himalayan knotweed, tobacco plant and Clark's geranium are fast-growing garden plants. The common sunflower, plume poppy and Himalayan knotweed are tall plants that grow several feet high, while the tobacco plant and Clark's geranium are widely-branching plants
The common sunflower is a stout annual plant that has hairy leaves and stems. Its terminal flower heads are very large, growing up to 5 inches in diameter. This plant grows in any type of soil and reaches its full potential when gardeners situate it in full sunlight.
The plume poppy grows up to 7 feet tall in one season. It stands upright without the aid of a stake. It thrives in sunlight, but is able to grow in partial shade. This plant's beige flowers bloom in mid- to late-summer.
The Himalayan knotweed grows up to 6 feet tall. Gardeners should not plant this overpowering plant amongst delicate plants. Its scented white flowers come fully into bloom by early- to mid-autumn.
The tobacco plant is very fragrant, especially at night. Hummingbirds are strongly attracted to the tobacco plant. It has white flowers and large, oval-shaped leaves that sprout sticky hairs during the summer and early fall.
Clark's geranium is a rugged, yet pretty plant that produces either violet or white flowers. Its growth does not interfere with plants growing above it. This plant spreads quickly across the ground, inhibiting the growth of garden weeds.