Winter Hardiness

• Native to Europe, baby's breath grows best in temperate climates with cool to warm summers and cold winters. Grow Million Stars in U.S. Department of Agriculture plant hardiness zones 4b through 8. Lack of winter cold during dormancy leads to plant demise, and winters colder than minus 25 degrees Fahrenheit can kill the roots. In subtropical regions, grow this perennial like an annual, expecting it to decline within a year. In USDA zones 9 and 10, plant seedlings in fall.
  
  

Climate Zones

• In the western United States, where great variation in elevation occurs, the USDA hardiness zones are not easily applied. Instead, "Sunset" magazine developed a climate zone map to better match plants with appropriate growing areas. Grow Million Stars baby's breath in Sunset climate zones A2, A3, 1 through 10, 14 through 16, 18 through 21 and H1. Baby's breath is not well-suited to deserts or regions with excessively hot and dry summers.
  
  

Summer Heat Tolerance

• Million Stars baby's breath will perform best in areas where no more than 150 days of temperatures above 85 degrees Fahrenheit occur. Excessive heat causes foliage and plants to die back when they should be photosynthesizing light and invigorating the roots prior to fall and winter dormancy. In hot summer regions, plant seedlings from November to January. The plants grow through the mild winter and bloom in late May or June before the summer heat withers them.
  
  

Growing Conditions

• Plant Million Stars baby's breath in a full sun garden setting; partial sun may be best in unirrigated areas or where the summers are hotter. A crumbly, light-textured fertile soil that is evenly moist but well-drained is best. Grow baby's breath only in neutral to alkaline soil types. Amend acidic soils with lime to raise the pH, otherwise the baby's breath doesn't grow well. Plant young baby's breath where it can grow permanently, as the deep taproot resents disturbance and doesn't transplant well.