Basil is a tender, annual, aromatic herb that grows from a single stem. It's a culinary herb with fragrant leaves that are used extensively as a condiment, paired with tomatoes, and also as a drink flavoring. If you grow basil, your goal is for the plant to produce as many leaves as possible and to make this happen, consistent pruning is required.
Pruning basil increases both stem and leaf growth. Sweet basil, the variety grown most often, can be shaped into a rounded bush 18 to 24 inches tall and wide. Basil grows easily from seed but it needs warm soil to germinate. is sensitive to temperatures below 45 degrees, and grows best in temperatures of 80 degrees and above. In northern climates, basil has a relatively short growing season. In more southern climates, the growing season may last a little longer, however constant warm temperatures encourage flowering.
Basil flowers attract pollinators, and also are edible, but allowing the herb to flower can cause the leaves to turn bitter. Flowering also leaves a terminal bud which halts the growth of new leaves. Just a few basil leaves are seldom sufficient for the basil lover. No matter where you live, plan to visit your basil plant often with a pair of herb snips and a harvest basket. You will soon be using the leaves collected as you prune.
For the best harvest, pruning should begin early to get the plant started off right with a branching habit. Each time you cut back a stem, 2 new stems will branch out from that cut, so consistent trimming is important to help the plant reach its most productive form. Follow these instructions for growing your basil into a full, bushy plant with plenty of delicious leaves.
When to Prune Basil
Basil is a plant that starts out with one central stem so you want begin pruning fairly early, when it is 6 to 8 inches tall and has 3 to 4 sets of opposite leaves. It can be tempting to harvest those early green leaves, but pruning too early can rob the plant of the energy it needs to grow. Snipping or pinching back the central stem to 1/4 inch above the first set of leaves will create two new branches. As the plant begins to bush out with multiple stems, you can prune up to half of each stem. Be sure to always pinch or cut just above a set of leaves. Harvest any leaves on the portion of stem you have pruned off.
To encourage additional branching and more leaves, you will need to prune your basil regularly throughout the growing season. This herb will grow quickly during warm weather and should be checked daily when temperatures approach 80 degrees. When grown from seed, sweet basil will reach maturity at 65 to 70 days and flowering will increase. Pinch back flower buds as they form as part of your pruning regimen.
The best time to harvest most aromatic herbs, which include basil, is in the morning after dew has dried or in the early evening before dew has fallen. The essential oils that give the herb fragrance and flavor are at their peak concentration during these times. Since pruning your basil will include harvesting, these times are also best for pruning tasks.
Equipment / Tools
- Herb snips
- Harvest basket
Pinch Back the Stem to Topmost Leaves
Whether you are growing basil in a pot or in the ground, make your first pruning cut when the plant is 6 to 8 inches tall and has 3 to 4 sets of opposite leaves.
Using your thumb and index finger pinch the central stem back to within 1/4 inch of either the topmost or second set of leaves. The central stem of the plant will be fairly slender and soft at this point so using snips is optional. Two new stems will grow from the pruned central stem.
Prune the New Stems to Half the Length
When the two new stems have produced several sets of leaves, pinch or snip each stem back by up to half its length. Remember to prune 1/4 inch above a set of leaves.
Place the pruned stems with leaves in your harvest basket to use in your favorite recipe.
Continue to Prune Often
Continue as above, keeping in mind that the more stems you prune, the bushier the plant will become and more leaves will be available to harvest. At peak growing season when you find yourself doing a lot of pruning on your basil plant, it will be easier and quicker to get the job done with a good pair of herb snips.
Watch For and Remove Flower Buds
Because basil grows best in warm temperatures of 80 degrees and higher, this plant has a tendency to flower and go to seed in the hottest months of the growing season.
Once flower buds begin to appear, you will need to stay vigilant and check your plant every day to remove them. Flower buds appear on the stem at the juncture of two leaves or stems.
The flower buds are easily pinched out using your thumb and index finger. Be sure to remove the entire bud. Any part left on the plant will cause that stem to cease producing new leaves.
Prune Even After Flowering
If you miss a few days and your basil does produce flowers, there's no need to panic. Remove the flowers—they're edible—and sprinkle them on a salad, or put them in a small vase of water.
To encourage new growth you can cut the entire plant back by half to encourage regrowth and use the leaves to make pesto.
Prepare for End of Season
Basil is intolerant of cold weather and can die back or develop black spots when night time temperatures dip just into the lower 40s.
As autumn weather approaches you may want to harvest the entire basil plant and dry or freeze the leaves for use during the off-season.