Perennial baby Breath Gypsophila Paniculata 'Snowflake

Sow directly as soon as the ground can be worked in spring or in Fall. Barely cover the seeds as they need light to germinate.
When sowing directly where they are to flower, choose a sunny open site with good drainage. Prepare the ground well and rake to a fine tilth before sowing,

Cultivation:
Pinch out the growing tip to encourage bushiness. Soil should not be too rich or you will get large plants with few flowers. Plain 'Top Soil' works best. Compost should be kept slightly moist, but not wet at all times. Do not fertilize, it will kill them.
Once they are established they need little care. When the flowers are removed for use in arrangements, the plant, will blossom with renewed vigour

As a cut-flower, assuming the water is kept clean; gypsophila is a relatively long-lasting flower, often out-living the other flowers in a bouquet. It also makes a nice dried flower, looking almost as good dried as it does when fresh from the florist. 

For bouquets, the day before you need them cut the stems in the late evening after the blossoms have opened. 
For longer lasting blooms: Carry a bucket of cool (not cold) water into the garden and immerse the stems immediately. Allow them to stand overnight in a cool, dark place to the harden stems before arranging the next day. 
For continual blooms: Leave 6 to 12" of stem on the plant and cut just above a leaf joint so the plant will produce more blooms.

7-12 Days