Before frost, harvest your basil leaves and preserve them Instead of bringing it indoors to continue to grow. Here are some options for how you can preserve your fresh basil.
Freeze Basil in Oil Cubes or Water Cubes – Fill ice cube tray with basil leaves and top with olive oil or water. Push any leaves poking out into the oil. Freeze for 24 hours or until solid. Remove the cubes from the ice cube tray and place in airtight freezer bag.
Freeze Massaged Basil Leaves in Oil – Strip basil leaves off stems and gently massage each leaf with oil. You'll need about 2-3 Tbsp of oil per 2 cups of basil leaves. Place in plastic bag and squeeze out all the air forming a thin, flat layer. The oil prevents the basil from turning black and once frozen you can just break off what you need.
Freeze Basil Leaves as is – Strip basil leaves off the stems and freeze them whole just as is – no oil, no water, no nothin’. The leaves turn very dark and will be soft and mushy when they thaw but they still have great taste for use where you won't see them - soups, stews and pasta dishes where looks and texture don’t matter.