Ocimum

( OSS - ih - mum )

At-A-Glance Information

This genus includes aromatic annual and perennial herbaceous plants and shrubs that are native to warm, temperate regions worldwide. The best known species are those cultivated for their tasty foliage, including Great Basil and Holy Basil (Tulsi). These plants do well in pots or in the ground, and are commonly included in potager, herb, or vegetable gardens.

Ocimum Species and Varietals

The genus Ocimum is the type genus member of the plant family Lamiaceae, and includes 160 distinct species. The genus name is derived from the Ancient Greek word for basil, okimon. The growing zones for these plants vary depending on the species; for more information, consult the information below. To find your zone, click here: Zone Map.

Ocimum americanum (Hoary Basil, Lime Basil, American Basil)
This species is native to Africa, India, China and Southeast Asia. It forms an annual plant that reaches up to a foot tall with toothed leaves and small white to purple flowers which bloom in clusters. This plant produces a deep taproot and is highly aromatic, with a fragrance similar to citrus. Foliage can be used as basil, and has a citrusy flavor to it. Best in USDA zones 9-11; frost-sensitive.

Ocimum basilicum (Basil, Great Basil)
This perennial culinary herb is a tender plant that is used in cuisines around the world. It is native to tropical areas from central Africa to Southeast Asia. In temperate climates, these plants are grown as annuals, but in warmer zones it can be a short-lived perennial or biennial plant. Plants typically reach up to between 1 and 5 feet tall when mature, and produce fragrant green (sometimes purple) foliage and small white flowers on upright spikes. These plants are ready to be harvested between 60 and 90 days from planting. These plants thrive in warm conditions, and are hardy to 50 degrees Fahrenheit. Best in USDA zones 10-11; treated as an annual in colder regions. There are many varieties of this species, listed and described below.

'African Blue'
A perennial sterile hybrid varietal of basil that has a strong camphor scent. Great for fruit teas and cocktails.

'Anise Basil'
Originally from Persia, these plants have dark stems and are great in Italian, Thai, and Mediterranean dishes. With anise scent and flavor.

'Cinnamon'
(Mexican Spice Basil)
Flavor and scent reminiscent of cinnamon. Dark green leaves with purple veining. Stems are dark purple, plants reach 18-30 inches tall.

'Dark Opal'
With deep purple, sometimes mottled leaves. Developed at the University of Connecticut. Foliage is purple, and flowers are pink-purple.

'Genovese' (Sweet Basil)
Produced in Italy, this popular varietal is used mainly for pesto.

'Greek'
This cultivar produces green leaves and are used in many culinary applications around the world.

'Globe' (Spicy Globe)
This variety forms a compact rounded bush, and is suitable for small gardens and container growing.

'Lemon'
(Lao Basil, Thai Lemon Basil)
Primarily grown in northeast Africa and southern Asia for its fragrant lemony scent. White flowers.

'Lettuce-Leaf'
A large-leaved variety that is not as strong as other basils. Great for salads, wrapping meats, or in stuffing or grilling.

'Neapolitano' (Mammoth)
To 18 inches tall, with ruffled large leaves that have jagged edges. Taste similar to Genovese Basil.

'Red Rubin'
Reddish-purple leaves with a stronger flavor than sweet basil. Good for salads and garnishes. To 2.3 feet tall.

'Thai'
Sturdy, compact plant to 1.5 feet tall. Purple stems and green foliage. Licorice and spicy undertones.

Ocimum campechianum (Alfavaca, Albahaca del Monte, Amazonian Basil, Wild Mosquito Plant, Mangericao, Estoraque)
This species of Basil is native to Mexico, Central America, South America, the West Indies and Florida. Its leaves have a pungent flavor, and are commonly used in ayahuasca brews. These plants do well in USDA zones 10a-13b.

Ocimum gratissimum (Clove Basil, African Basil, Wild Basil, Scent Leaves, Nunu Bush, Scent Leaf)
Native to Africa, Madagascar, Southern Asia, and the Bismarck Archipelago. This species produces fragrant foliage, and is used in its native range in soups, rice, beans, and other delicacies. Repellent to thrips. Holy Basil is best in USDA growing zones 10 and 11.

Ocimum tenuiflorum (Holy Basil, Tulsi, Tulasi)
This aromatic perennial plant is widely cultivated throughout the world, and is native to tropical and subtropical areas of Asia, Australia, and the Western Pacific. It is cultivated for religious purposes as well as to extract essential oils. Plants reach up to 2 feet tall at maturity. Holy Basil, or Tulsi, does best in USDA growing zones 10-11, but can be grown as an annual in cooler climates.

Caring for Ocimum

Basil plants are typically either planted via seed (direct-sown or started indoors and planted out) or as starts purchased from a reputable nursery. Basil plants started from seed indoors will need to have about 6-weeks of development before they are ready to be transplanted out (which should only happen after the last frost of your area has passed). Space Basil plants between 12 and 24 inches apart for best coverage and airflow. Choose a space in the landscape that receives between 6 and 8 hours of sun each day. In warmer climates, plants appreciate some afternoon shade when temperatures are at their peak (typically between 2 and 3 PM). Ensure that soil is well-draining, rich in nutrients, and has a pH of between 6.0 and 7.0 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, Basil plants like to get water on a regular basis; as a general rule of thumb, irrigate whenever the top inch or two of soil feels dry to the touch.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prevent Basil from blooming if you will be harvesting it for its leaves. Plants can be pinched back when they reach about 6 inches in height to encourage a bushier habit to form, which will provide more leaves for harvesting. Pruning for aesthetics is not necessary for these plants; they typically take a bushy, attractive form and are considered more crop plants than ornamentals in the landscape.

Harvesting Basil
Ocimum, or Basil, plants are typically grown for their fragrant, tasty foliage. Plants can be harvested beginning when they are between 6 and 8 inches tall. Harvested leaves can be used fresh, dried, or even be frozen for later use. Dried Basil is a convenient herb, but the drying process does cause some flavor to be lost. Frozen Basil has a stronger flavor, but a somewhat odd texture, and is best in cooked dishes like soups and pasta sauces. Remove leaves individually or by stem using a pair of sharp, clean shears or snips. The best time of the day to harvest Basil leaves is in the morning, after the dew has dried but before the heat of the day sets in. Although individual leaves are best used fresh, harvested stems can be dropped in a glass of cool water and stored on the counter for harvesting over the next week or so. Do not store Basil leaves or stems in the refrigerator, as this will cause the leaves to blacken and wilt.

Propagation

Ocimum, or Basil, can be propagated by cutting or seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, especially if you are propagating a hybrid cultivar. To propagate your Basil, follow the instructions below:

Propagating Ocimum by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Ocimum by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
In early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new plant.