Basil: An Herb Society of America Guide
Pruning & Harvesting
According to Madalene Hill and Gwen Barclay, proper pruning and harvesting is the "secret" to growing basil (44). Consider pruning a means for continual harvest. By pruning your basil often, the plant will stay healthy and robust and will produce many harvests throughout the season.
Different sources have different recommendations on when to start pruning. Madalene and Gwen like to "nip off the end growth of each branch to encourage new growth" just prior to transplanting (45). Susan Belsinger recommends pruning when
the plant has three sets of true leaves (8). In
The Big Book of Herbs, Art Tucker and Tom DeBaggio suggest pruning when
the plant has three leaf pairs and is
1 foot tall (79). Others recommend pruning when plants have six to eight sets of true leaves (24, 38, 45). James Adams usually prunes basil when it has four to five nodes (1).
For the first pruning, cut the plant just above its second set of leaves (8, 44). Plants should be pruned in this manner whenever repotted or transplanted (45). Continue to prune every 3-4 weeks (8, 44), cutting plants back to the lower one-third of the plant (51) or just above the lowest two to four leaves (45) or second leaf node (8). Harvesting in this manner can produce as much as 15-24 cups of basil in a season from a single plant (8).
If you prefer to harvest more frequently and less dramatically, snip off the top set of leaves just above the next lower node as needed. Depending on your basil's growth rate, this may be as often as once a week (1).
After flowering, when seeds have matured, basils will stop producing new leaves (24, 44, 45). To ensure continued growth, cut off any flower buds that begin to form (8, 62). Be sure to cut the branch rather than just the tips or new buds will quickly appear (45).
Many basil lovers claim that flowering will also cause the leaves to have a bitter taste. Mark Langan points out that preventing flowering is only required for annual basils (rather than perennial), since flowering marks the beginning of the end of an annual plant's life cycle. Mark believes that flowering doesn't affect the flavor of tender perennial basils (51). Try growing a variety of basils, and judge for yourself!
Even annual basils can and should be allowed to flower at the end of the growing season. Flowers can be enjoyed for their beauty, then harvested and used in a variety of dishes.
Harvest Time
Traditionally, the best time to harvest basil is in the morning when the essential oils are strongest, after the morning dew but before the heat of the afternoon sun. Contrary to popular wisdom, however, University of Michigan researchers have found that harvesting basil in the evening between 6 and 10 p.m. increases its shelf life (79). This finding may be of particular interest to commercial basil growers (45). If all else fails, and you only need a small amount of basil to add to a favorite dish, follow the lead of Madalene Hill and Gwen Barclay and harvest when you have the time. For large harvests, however, Madalene and Gwen recommend harvesting in the morning and hosing basil off the previous evening to rinse off any dust (44, 45).
Next topic: Preserving & Storing