Basil

Basil is one of the most rewarding culinary herbs to grow, indoors or out.

This member of the mint family may not be as rugged as many of its cousins, but you’ll be glad you planted basil when it’s dinnertime! 

Fresh basil

Basil seeds are used in Thai cooking and the leaves are used to make many amazing dishes. Aromatic basil leaves, julienned with mozzarella and fresh tomatoes, make a delightful summer Caprese salad, and what would pesto be without basil?!!?

Basil varieties

There are many varieties of basil. Sweet basil (Ocimum basilicum) is the most common, but you can also find these varieties:

• Purple or opal basils (Ocimum basilicum purpurea) are big favorites of bees and it looks and tastes lovely in salads.
• Lemon or lime basil (Ocimum basilicum citriodorum) pairs nicely with fish.
• Licorice-flavored Thai basil (Ocimum basilicum ‘Siam Queen’) has serrated leaf edges.
• Cinnamon basil (Ocimum basilicum ‘Cinnamon’) has a distinctly cinnamon flavor.
• Greek or globe basil (Ocimum basilicum 'Spicy Globe’) has very tiny leaves and makes a lovely little topiary tree.

How to grow basil

As a tender annual, temperatures must be at least 70ºF for basil to grow. Start too soon and you’ll just waste seeds. Basil loves hot weather, but may benefit from a little afternoon shade if your summers are really scorching. I have planted basil slightly east of a small apricot tree, in patio containers, and in a partially shaded tower. Our summers get very hot and basil performs well in each of these locations. If you are growing basil in a container, be sure to use one that is large enough to hang onto some moisture.

Start seeds indoors, 6-8 weeks before warmer temperatures are expected, to get a big head start on the growing season. You can also use succession planting to increase yield. Basil can be started from cuttings. Simply pinch off a stem and place it in a glass of water. This is an excellent way to make many plants out of a single plant!

Basil seeds should be planted 1/4” deep. The soil should be kept moist, but not soggy. In 5-7 days, seeds should germinate. It is easy to recognize basil seed leaves because they look like two capital D’s, facing away from each other. Seedlings need 12-18” between plants to reach full size and for good airflow. A 2-3” layer of mulch placed around young plants will help retain moisture and reduce weeds. ​

Thai basil seedlings

Basil needs 6-8 hours of sunlight a day and it prefers well-drained soil with a pH of 6.0-7.5. Depending on rainfall and temperatures, basil will need to be watered deeply every 7-10 days. Since basil is food, think twice about using any chemical pesticides. 

BTW, ignore basil plants for sale in the grocery store. They look lush and full, but what they really are is overcrowded and root bound. If you try to separate the plants, it will damage the roots too much. Leave them the way they are and they will simply choke themselves to death. Even if they survive, air flow problems can lead to fungal disease. Buy a pack of seeds and share with friends.

Basil pests & diseases

Aphids, spider mites, nematodes, cutworms, slugs and snails, mealybugs, and fungal diseases can all cause problems on basil. Adding a ring of wood ashes around each plant may protect them against cutworms, and dusting plants with diatomaceous earth can reduce mealybug damage. Planting nasturtiums nearby is said to entice aphids away from basil. Apparently, aphids prefer nasturtiums, so you get more basil. Whether it works or not, the nasturtiums are lovely and tasty, all on their own. Row covers can be used to protect basil from many of these pests.

Ensuring good air flow between plants and proper watering make a big difference in basil health. Too much water can cause root rot diseases. Allow plants to dry out between waterings. Stem rot, Fusarium wilt, bacterial leafspot, gray mold, and damping-off disease can also infect basil. A relatively new disease, basil downy mildew, has made its way to California. Be on the lookout for purple or gray spore growth on the underside of leaves. Infected plants must be destroyed.

Basil makes an excellent companion plant to asparagus, carrots, sweet peppers, and tomatoes. Apparently, asparagus beetles, carrot flies and tomato hornworms don’t share our love of basil. While there is no scientific proof, many gardeners believe flies, mosquitoes and whiteflies are also repelled by basil. Whether it works or not, I can’t plant enough of this delicious herb!

Harvesting basil

Snip fresh leaves any time they are needed in the kitchen. If more than a few leaves are needed, or if the plant is getting leggy, cut just above a pair of leaves to stimulate new branching. Regular trimming will keep the plant productive. The basic rule of thumb is to pinch a stem just above a pair of leaves as soon as a stem has 5 or 6 leaves on it. If basil is allowed to go to flower and seed, the leaves may begin to taste slightly bitter. (The bees will love it, though!) Basil flowers are edible and they look lovely in a salad or candied and used to decorate baked goods.

Pinching back basil

Pinching stimulates bushy growth in basil

Storing basil

Basil leaves can be dried or frozen. To dry basil, cut the stems and rinse off any dust, insects or microorganisms. Then pat dry and hang the basil stems upside down until the leaves have dried out completely, just as you would with lavender and other herbs. Once the leaves have dried out completely, they can be removed from the stems by rolling them between your hands over a sheet of wax paper. Store in a dark, dry location. (I repurpose spice jars that used to hold something else and that have been thoroughly washed and dried.) To freeze fresh basil leaves, rinse them off, pat dry and remove from the stem. Leaves can be frozen whole (not recommended) or pureed and then frozen in ice cube trays for easy portion control. My very favorite use for basil is pesto, which can transform everyday pasta, chicken, or pork into something truly delicious!

If you have a large container, you can create a lovely miniature herb garden by planting parsley, chives, oregano and basil together. The spiky chives, trailing oregano and bushy parsley and basil make a lovely arrangement that tastes even better than it looks!