Line the bottom of a pot with an inch of gravel. The pot should have drainage holes to keep the water from drowning the plant, and the gravel will keep the pot well-drained as well.
Fill the pot three-fourths full with potting soil.
Remove the seedling lavender plant from its container by gently squeezing the container until the soil ball pops out. Because lavender does not breed true from seed, it is more effective to buy young plants and transplant them.
Set the lavender in the pot.
Add potting soil around the plant until the pot is full.
Firm the soil around the plant.
Place the lavender pot in a place where it receives at least eight hours of sun.
Water whenever the soil feels moist.
Trim back the branches when the lavender is 1 year old. Restrict your pruning to the early spring, when there is new growth. According to Purdue University, you should only trim the new growth.