Pick small, succulent leaves from the top of the basil plant by hand, recommends Deborah Weschler on the National Gardening Association website. Pull the leaf gently to separate the leaf from the remainder of the plant. Pick frequently, as needed for use in culinary dishes.
Use a pair of scissors to cut basil stems just below the top two leaves on the plant. Cut the stems about 1/4 inch above the leaf node, recommends Fyffe Court on the Ohio State University Extension website. Combing this harvesting practice along with picking the small, top leaves encourages basil to continue to grow throughout the season.
Fill a small jar 3/4 full with cool water. Place harvested basil leaves with stems in the jar so the stems are in the water, but the leaves are not.
Change water every two or three days. Gently pull leaves off the stems as needed.
Store extra leaves in freezer plastic bags. Keep in the freezer and pull out leaves when ready to use throughout the winter.
Chop a few leaves into small pieces. Fill each section of ice cube trays half full with basil leaves. Pour water over the basil and store in the freezer. Drop basil cubes in sauces or soups to add flavor.