Basil plants are one of the most popular herbs to grow and also one of the easiest. Sweet basil (Ocimum basilicum) is a member of the mint family. It is closely identified with Italian cooking, although it is originally from India. The extremely aromatic leaves also have a delightful variety of flavors, from the slightly lemony-mint of sweet basil to cinnamon and licorice. Leaf colors span from rich green to deep purple, with smooth or crinkled leaves. The flowers are insignificant but very popular with bees.
All types of basil grow easily in warm, sunny weather. The leaves are commonly used in cooking, but the flower buds are also edible. This fast-growing herb thrives equally well in gardens and containers. With sufficiently warm weather, new basil plants are ready for pruning (to encourage bushier growth) in about six weeks.
|Botanical Name||Ocimum basilicum|
|Common Name||Sweet basil|
|Plant Type||Perennial or annual herb|
|Mature Size||18–24 inches tall and wide|
|Sun Exposure||Full sun (likes some shade in very hot climates)|
|Soil Type||Somewhat rich soil|
|Soil pH||5.1– 8.5 (acidic to alkaline)|
|Bloom Time||June to frost|
|Hardiness Zones||10-11 (grown as an annual elsewhere)|
|Native Area||Central Africa to Southeast Asia|
How to Plant Sweet Basil
Sweet basil is a warm-weather herb, so it is often planted from nursery transplants that have been started in greenhouse conditions. If you grow basil from seeds, you will need to start them indoors about six weeks before your last spring frost. Basil is ready to start harvesting in about 60 to 90 days from seeding.
Prevent your basil from blooming for as long as possible by harvesting or pinching off the top sets of leaves as soon as the plant reaches about 6 inches in height. If the plant sets flowers, it is on its way to going to seed and will not grow bushy and fill out with a lot of tasty leaves.
The size of your plant will depend on the variety, the growing conditions, and how much you harvest. Sweet basil (Ocimum basilicum) can reach 6 feet tall but typically grows to about 18 to 24 inches—or even shorter, since its height is kept in check if you're harvesting regularly and not letting the plant flower. Continually pinching and using your basil will coax it into becoming bushy, with more leaves. There are also short 6-inch dwarf varieties, which work especially well in pots.
Basil grows best with six to eight hours of full sun each day. Ample sun also means fewer disease problems and sturdier plants. This is the case except in the hottest climates, where basil prefers part shade.
Basil does best in moist, rich, well-draining soil. It's a good idea to amend your soil with compost or other nutrient-rich mulch.
Water basil deeply on a regular basis, but be sure its soil is well-drained. Use mulch to help keep moisture in.
Temperature and Humidity
Basil is a heat lover. Don't bother planting it until the daytime temperatures remain in the 70s and night temperatures are above 50 degrees Fahrenheit. Basil is very sensitive to frost and will be one of the first plants to die in the fall. You can extend the season slightly by covering your plants with row covers when frost is threatened. Don't let the row cover touch the leaves—frost on the outside of the row cover is enough to damage the tender leaves, likely turning them black.
If you live in a frost-free area, you might want to allow some basil plants to set flowers and self-seed in your garden. Not all varieties will do this successfully.
Because you will be harvesting leaves from your basil plants, you may need to fertilize them often. An all-purpose fertilizer works well and helps ensure that new leaves will grow continuously.
Varieties of Basil
There are many cultivars of sweet basil, as well as other related species with unique tastes. Try these different kinds of basil:
- 'Genovese' (Ocimum basilicum 'Genovese'): This variety has larger leaves than the species sweet basil, with all the flavor.
- 'Cinnamon' or 'Mexican Spice' (Ocimum basilicum 'Cinnamon'): Enjoy the green foliage, purple flowers, and spicy, cinnamon scent.
- Lemon basil (Ocimum basilicum x citriodorum): This is a hybrid plant with a distinct odor and taste of citrus.
- Thai basil (Ocimum. basilicum var. thyrsiflora): This variety of sweet basil has a sweeter taste with a hint of licorice. It is very common in Asian cuisine, especially Vietnamese dishes.
Growing Basil in Containers
Basil works in almost any type of pot or container, even a kiddie pool. But there are two rules for success: keeping the soil moist and not crowding the plants. The easiest way to follow both rules is to plant in large, deep pots, which means more soil for moisture retention and more real estate for spreading out multiple plants and ensuring adequate air circulation. You can plant them as close as 6 to 8 inches apart if you desire a full look to your containers, but spacing them 12 to 18 inches apart is better for air circulation. Overcrowded plants are vulnerable to fungal problems.
To make sure your container plants are properly hydrated, check the soil daily by sticking your finger in to the second knuckle, and water when the soil feels dry at this depth. Use a quality potting soil that drains well so the roots do not sit in water. Also, make sure the container has drainage holes. If the soil is not premixed with fertilizer, add some organic plant food and mix it in well when filling the pot. Thereafter, feed the plants every two weeks with diluted liquid fertilizer.
You can start harvesting basil leaves when the plants are 6 to 8 inches tall. Even if you are not using the leaves in cooking or drying or freezing them, picking leaves regularly will improve the plant's vitality. Basil leaves can be dried or frozen for use after harvest. Dried basil is convenient but at the cost of some flavor. Frozen basil has a stronger basil flavor than dried but at the cost of texture. Use frozen basil in cooked dishes. If you like to cook with basil and olive oil, blend fresh basil with your favorite olive oil and portion it into an ice tray for freezing. Store the frozen cubes in an airtight container.
Basil can be used in cooking, generally added at the end to keep its fresh taste and color. Basil can also be used fresh in salads, on sandwiches, or even as a wrap—around cheese cubes, for instance. One of the most popular culinary uses of Genovese basil is in the classic northern Italian pesto, traditionally made with fresh basil, Parmigiano Reggiano and Romano cheeses, fresh garlic, olive oil, and salt. Puree the mixture in a food processor or blender, and stir it directly into freshly cooked pasta (with a bit of pasta water to keep it slightly loose).
Common Pests and Diseases
Aphids are the biggest basil pest, especially with plants grown indoors. Beetles and slugs also can be a nuisance outdoors, creating holes in the leaves. Cover your entire plant with a soap solution of 2 teaspoons of dishwashing liquid to a full gallon of water to eradicate these pests.
Basil is susceptible to powdery mildew, which can be controlled by providing plenty of space between plants to improve air circulation, and avoiding overhead watering, which can splash fungal spores onto the plants. Severely affected leaves should be picked off and discarded.