This is a list of the twenty-one easiest flowers for beginner gardeners to guarantee success. The list is divided into annuals, perennials and bulbs and includes the zones, colors and heights of each plant. The particular all-star qualities are described as well as brief growing tips. I came across this useful list on the Garden Design Magazine website.

Sunflowers

Zones: Annual
Colors: Yellows, browns, and mixed
Height: 3-16 feet

• Thrives in full sun
• Tolerates most soil types (except water-logged)
• May require support to prevent breakage

Zinnias

Zones: Annual
Height: 20-24 inches
Colors: Shades of red, orange, yellow, pink, and white

• Likes rich, well-drained soil
• Has moderate water requirements
• Grows best in full sun

Marigolds

Zones: Annual
Height: 6-36 inches
Colors: Shades of yellow, red, gold, and mixed

• Prefers well-drained soil, grows well in dry or sandy gardens
• Water well, allow to dry between waterings
• Should be grown in full sun

Cosmos

Zones: Annual
Height: Varieties 18-60 inches
Colors: Orange, pink, white

• Prefer moist, well-drained soil, but can tolerate dry spells
• Water regularly, but don?t over-water
• Grow in full sun, with afternoon shade in hot climates
• Will self-sow for the following year if seeds left to scatter in fall

See more at Garden Design Magazine