Sweet basil is a species of mint plant native to Asia and Africa. It is a popular houseplant, and thrives when it receives plenty of regular sun and water. This plant is also easy to transfer from one soil environment to another. The edible sweet basil leaves can be eaten fresh or dried with pizza, salads, soups, teas, and many other dishes.
I. Appearance and Characteristics
Basil (Ocimum basilicum ), also called great basil, is a culinary herb of the family Lamiaceae (mints). It is a tender plant, and is used in cuisines worldwide. In Western cuisine, the generic term “basil” refers to the variety also known as sweet basil or Genovese basil. Basil is native to tropical regions from Central Africa to Southeast Asia. In temperate climates basil is treated as an annual plant, however, basil can be grown as a short-lived perennial or biennial in warmer horticultural zones with tropical or Mediterranean climates.
There are many varieties of basil including sweet basil, Thai basil (O. basilicum var. thyrsiflora), and Mrs. Burns’ Lemon (O. basilicum var. citriodora). O. basilicum can cross-pollinate with other species of the Ocimum genus, producing hybrids such as lemon basil (O. × citriodorum) and African blue basil (O. × kilimandscharicum).
Basil is an annual, or sometimes perennial, herb used for its leaves. Depending on the variety, plants can reach heights of between 30 and 150 centimetres (1 and 5 feet). Basil leaves are glossy and ovulate, with smooth or slightly toothed edges that typically cup slightly; the leaves are arranged oppositely along the square stems. Leaves may be green or purple. Its flowers are small and white, and grow from a central inflorescence, or spike, that emerges from the central stem atop the plant. Unusual among Lamiaceae, the four stamens and the pistil are not pushed under the upper lip of the corolla, but lie over the inferior lip. After entomophilous pollination, the corolla falls off and four round achenes develop inside the bilabiate calyx.
Basil is sensitive to cold, with best growth in hot, dry conditions. It behaves as an annual if there is any chance of a frost. However, due to its popularity, basil is cultivated in many countries around the world. Production areas include countries in the Mediterranean area, those in the temperate zone, and others in subtropical climates.
II. How to Grow and Care
Sunlight
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.
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.
Watering
Sweet basil likes a moist environment. Frequent watering is required for seedlings to keep the soil moist. Established plants should be watered once every 4-6 days in spring and fall, and every 2-4 days in summer. In winter, move inside and reduce watering.
Also, it is preferable to use rainwater and distilled water, because tap water may contain a lot of calcium, magnesium, and other mineral salts, and long-term use tends to compact the soil. Inserting a finger into the flowerpot soil. If the soil is particularly hard and dry, it needs to be watered immediately. If the soil is soft and wet, no immediate watering is required.
Soil
Sweet basil is a deep-rooted plant, with the roots growing up to 51 to 102 cm deep. Therefore, well-drained, fertile, loose sandy loam or humus soil is the best culture soil. Potted plants can be planted in a mixed culture of peat and vermiculite at 2:1, or garden soil and fully decomposed organic fertilizer at 2:1.
Sweet basil does not have strict requirements on soil conditions. It can be planted in both acid and alkaline soil and can tolerate pH values of 5-8, but neutral soil is the best.
Fertilizing
An appropriate amount of quick-acting fertilizer can make sweet basil grow better based on the principle of less fertilizer applied more frequently. In the case of fertilizer deficiency, sweet basil will be short. In the prosperous growing period, organic fertilizer can be applied once every two weeks. Observe its growth and keep it growing healthily.
During spring and fall, the roots, stem, and leaves grow and the flower buds differentiate. In summer, the temperature is high and the water evaporation is fast. Liquid fertilizer should be applied in small amounts but frequently. In winter, the temperature is low and the plant grows slowly or even stops growing, so no fertilizer is required generally.
Planting Instructions
Sweet basil is generally sown in spring and fall, and the best time for sowing is a sunny morning. The soil can be exposed to sunlight before sowing to kill harmful microorganisms in the soil. Select plump, pest-free seeds, spread them evenly in the soil, cover them with a layer of 5 mm thick soil, and spray water gently. If you worry about uneven sowing, you can mix the seeds with fine soil in advance and then spread them in the garden.
The best temperature for sowing sweet basil is about 20 ℃, and the seedlings are expected to grow in 4-5 days. When they grow 1-2 leaves, poor or excessively dense seedlings may be removed, and the spacing of seedlings set to about 3 to 4 cm. When 8-10 leaves grow out on one plant, the plant can be transplanted. Keep plants spaced to about 25 cm apart.
Pruning
Sweet basil can be pruned when they reach 20 cm in height. Yellow leaves, once found, should be cut off promptly. If the plant grows too exuberantly and the ornamental effect deteriorates, redundant branches can be cut off. After pruning, add a small amount of slow-release fertilizer. Sweet basil usually dies after the seeds are ripened, and its life can be extended by cutting off the flowers to prevent the seeds from ripening.
Propagation
Sweet basil can be propagated by cuttage or sowing. Sowing is the main cultural method for families.
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.
III. Uses and Benefits
Folk medicine
Basil is used in folk medicine practices, such as those of Ayurveda or traditional Chinese medicine.
Culinary uses
Basil is most commonly used fresh in recipes. In general, it is added last, as cooking quickly destroys the flavor. The fresh herb can be kept for a short time in plastic bags in the refrigerator, or for a longer period in the freezer, after being blanched quickly in boiling water.
- Leaves and flowers
The most commonly used Mediterranean basil cultivars are “Genovese”, “Purple Ruffles”, “Mammoth”, “Cinnamon”, “Lemon”, “Globe”, and “African Blue”. Basil is one of the main ingredients in pesto, an Italian sauce with olive oil and basil as its primary ingredients. Many national cuisines use fresh or dried basils in soups and other foods, such as to thicken soups. Basil is commonly steeped in cream or milk to create flavor in ice cream or chocolate truffles.
Lemon basil has a strong lemony smell and flavor due to the presence of citral. It is widely used in Indonesia, where it is called kemangi and served raw as an accompaniment to meat or fish.
- Seeds
When soaked in water, the seeds of several basil varieties become gelatinous, and are used in Asian drinks and desserts such as the Indian faluda, the Iranian sharbat-e-rihan, or hột é. In Kashmir, the Ramadan fast is often broken with babre beole, a sharbat made with basil seeds.
Insecticide and insect repellent
Studies of the essential oil have shown insecticidal and insect-repelling properties, including potential toxicity to mosquitos. The essential oil is found by Huignard et al. 2008 to inhibit electrical activity by decreasing action potential amplitude, by shortening the post hyperpolarization phase, and reducing the action frequency of action potentials. In Huignard’s opinion this is due to the linalool and estragole, the amplitude reduction due to linalool, and the phase shortening due to both.
Callosobruchus maculatus, a pest which affects cowpea, is repelled by the essential oil. The essential oil mixed with kaolin is both an adulticide and an ovicide, effective for three months against C. maculatus in cowpea. The thrips Frankliniella occidentalis and Thrips tabaci are repelled by O. basilicum, making this useful as an insect repellent in other crops. The pests Sitophilus oryzae, Stegobium paniceum, Tribolium castaneum, and Bruchus chinensis are evaluated by Deshpande et al. 1974 and ’77.
Nematicide
The essential oil is found by Malik et al. 1987 and Sangwan et al. 1990 to be nematicidal against Tylenchulus semipenetrans, Meloidogyne javanica, Anguina tritici, and Heterodera cajani.
Bacterial and fungal inhibition
The essential oil of the leaf and/or terminal shoot is effective against a large number of bacterial species including Lactiplantibacillus plantarum and Pseudomonas spp. The essential oil of leaf and/or terminal shoot is also effective against a large number of fungal species including Aspergillus spp., Candida spp., Mucor spp., and Geotrichum candidum.
IV. Harvesting and Storage
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.
