Basil is one of those wonderful garden plants that just keeps coming. Unlike radishes and beets that are done once you harvest them, basil plants provide their pungent goodness for months if you can stay on top of them.
Basil should be harvested regularly to prevent flowering; trim the plants as soon as you see flower heads start to form. To do so, simply use scissors to trim off the upper leaf clusters, making your cut close to the set of leaves below. Often, you’ll need to cut more than one leaf cluster, and that’s okay. Just be sure to snip right above the set of leaves you’re planning to leave on the plant. New growth will sprout from that point so you can continue to harvest throughout the season.
You’ll want to make sure to leave some green growth so that the plant can do its photosynthesis thing, but the plant will be noticeably smaller. Healthy basil plants will need to be harvested every week or two. I have almost a dozen plants and these provide enough basil every time I harvest to make two batches of pesto – one to eat fresh, one for the freezer.
These harvesting rules apply for growing basil indoors, too, though an indoor basil plant might not need to be trimmed as frequently.