Wet Soil

• Sites with wet, boggy or clay soil can be among the most challenging sites for gardeners. Not many plants can thrive in wet sites, but exceptions include the marsh marigold. This perennial grows between 12 and 18 inches tall and thrives in wet soil and sun to partial shade. Marsh marigolds bloom in spring with yellow flowers and can tolerate standing water.
  
  The cardinal flower can also tolerate wet soil. A perennial, the cardinal flower can grow up to 4 feet tall and blooms in late summer with tall spikes of bright red blossoms. Cardinal flowers grow best in partial shade.
  
  

Drought

• Many parts of the United States regularly experience droughtlike conditions. For flowers that thrive in the dry soils, choose drought-tolerant plants. These include the daylily, a perennial that grows to 3 feet tall and blooms through spring and summer with pink, yellow, orange and maroon flowers. Daylilies thrive in full sun to partial shade and tolerate dry, but enriched, soils.
  
  While most annuals need consistent moisture to thrive, some tolerate dry soil. These include the Dahlberg daisy, a 4- to 8-inch-tall annual that spreads up to 18 inches wide and produces yellow blossoms from summer to fall. The spiderflower tolerates both drought and heat and produces pink, lavender or white flowers with long stamens from summer to early autumn. This annual grows to 72 inches tall.
  
  

Cold Temperatures

• If you live in U.S. Department of Agriculture plant hardiness zone 3 or 4, temperatures in your region can reach as low as minus 30 to minus 40 degrees Fahrenheit. For flowers that thrive in these cool zones, choose cold-hardy plants such as the balloon flower, a 3-foot-tall perennial hardy in zones 3 to 8. Balloon flowers bloom from late spring through summer with blue and white blossoms and prefer sites with full sun to partial shade. Plant balloon flowers in well-drained, acidic soil.
  
  The daisy fleabane tolerates even colder temperatures. This perennial is hardy in zones 2 to 8 and prefers dry soil and full sun to partial shade. Daisy fleabanes bloom in summer with white, purple, pink and orange flowers that have daisylike yellow centers. They grow from 1 to 2 feet tall.
  
  

High Altitude

• To grow at altitudes more than 7,500 feet, flowers must be cold-hardy in USDA zones 2 to 4 and must tolerate short growing seasons and dry soils. High-elevation-tolerant flowers include the long-blooming yarrow. Yarrow grows between 1 and 4 feet tall and blooms in midsummer with white, yellow, orange, red and pink blossoms. This deer- and rabbit-resistant perennial has aromatic foliage and thrives in full sun and dry soil.
  
  Monkshood also tolerates high elevations, as well as shade, deer, rabbits and many pests and diseases. Monkshood grows to 4 feet tall, blooms with purple to pink flowers in midsummer and prefers moist, shady sites.