Black Tulsi

Black tulsi is not a separate species. It is Ocimum tenuiflorum (syn. Ocimum sanctum), the same holy basil as green Rama tulsi, in its dark-leaved form. It belongs to the mint family, Lamiaceae. The "black" is really a deep violet, produced by anthocyanins, the same group of pigments that colour jamun and red cabbage. Shyama means dark, and it is also one of Lord Krishna's names, which is how the plant got both of its popular titles.

What you will notice:

• Leaves. Oval and softly toothed, about 2–5 cm long. They are green washed with plum, darkest on the upper leaves in strong sun. New leaves at the tips are often deep plum.
• Stems. Near-black, finely hairy, turning woody at the base with age.
• Flowers. Slim manjari spikes of small, pale lilac to pinkish flowers held in dark cups.
• Scent. Crush a leaf and you get a warm, clove-like smell with more bite than green tulsi.
• Habit. An upright, branching shrublet, usually 30–60 cm tall in a pot.

Black tulsi or green tulsi: which should you choose?

Both are the same plant species and need the same care. The differences are colour, aroma and pace:

• Colour. Krishna tulsi brings dark stems and plum-flushed leaves; Rama tulsi is bright green throughout.
• Aroma. The dark form smells sharper and more peppery; the green form is milder and slightly sweet.
• Growth. Many growers find the purple type a little slower and less leafy than the green one, especially in partial shade.

Choose the dark form for its colour, its contrast against a white mancha and its association with Krishna. If quick, leafy growth matters more to you, pick green Rama tulsi for the courtyard instead. Many households grow one of each in the same sunny spot.

Why are my black tulsi leaves turning green?

It is almost always the light, not the plant. Purple colour develops most strongly in bright sun. In shade, under grey monsoon skies or on soft, fast growth after heavy feeding, new leaves come up greener, while the stems usually stay dark. Once the plant gets four to six hours of direct sun again, fresh leaves darken within a few weeks. To keep the colour deep, give it your sunniest spot, feed lightly and pinch the tips so new growth stays compact.

Where should you keep a black tulsi plant?

Pick the spot with the longest hours of direct sun:

• A courtyard or tulsi mancha. The traditional place, raised above rainwater and in full view of the house.
• A south- or west-facing balcony. It is one of the most rewarding balcony plants for a hot, west-facing ledge since strong afternoon light keeps the leaves dark. Shade young plants for a few weeks in May.
• An open terrace. It is one of the easiest plants for a home terrace garden, as long as the pot sits on bricks so it drains after rain.
• A sunny windowsill, for short spells. Only a sill with four or more hours of direct sun will do.
• Not inside a puja room or a dim flat. In low light the leaves turn green, stems stretch and the plant declines within weeks. Bring it indoors for a festival day, then return it to the sun.

Product Specifications

• Plant name: Black Tulsi (Krishna Tulsi) Plant
• Botanical name: Ocimum tenuiflorum (syn. Ocimum sanctum), purple-leaved form
• Common names: Black tulsi, Krishna tulsi, Shyama tulsi, purple tulsi, purple holy basil
• Plant family: Lamiaceae (mint family)
• Origin: Indian subcontinent and South-East Asia
• Plant type: Aromatic herb; short-lived perennial shrublet
• Leaves: Oval, softly toothed, about 2–5 cm, green flushed purple; colour deepens in full sun
• Stems: Dark purple to near-black, finely hairy
• Flowers: Small, pale purple to pinkish, on slender spikes (manjari) with purple calyces
• Aroma: Strong, warm and peppery, with a clove note
• Growth habit: Upright and branching; bushy when pinched
• Growth rate: Moderate in warm weather; slow in winter
• Mature size: About 30–60 cm in a pot
• Lifespan: Usually 2–3 productive years; self-seeds
• Suitable placement: Courtyard, tulsi mancha, sunny balcony, terrace, garden bed; outdoors or a very sunny sill only
• Light requirement: Full sun; at least four hours of direct sun daily, ideally six
• Water requirement: Moderate; water when the top 2–3 cm is dry; no waterlogging
• Soil requirement: Light, gritty, well-drained loam with compost
• Temperature: Thrives in warm weather; suffers in prolonged cold below about 10 °C; not frost-hardy
• Fertiliser: Light compost or vermicompost every 5–6 weeks, March to October
• Maintenance: Low; regular pinching of flower spikes and tips
• Common pests and problems: Aphids, whitefly, lace bug, mealybug, caterpillars; stem rot in waterlogged soil; winter leaf drop; green leaves in low light
• Difficulty level: Easy, with enough sun
• Suitable environment: Warm plains, coast and hills across India; needs winter protection in the north
• Safety: Holy basil is not listed by the ASPCA; not classed as pet-safe

How do you care for a black tulsi plant?

• Soil. A loose, gritty mix: two parts garden soil, one part compost or old cow dung manure and one part coarse sand or cocopeat. Avoid sticky clay that stays wet.
• Watering. Check with a finger, not a calendar. In April and May the pot may need water every morning; in the rains and in winter, perhaps once a week. Empty the saucer each time.
• Sun. Full sun keeps the plant compact and purple. If it has turned green and stretched, move it before you change anything else.
• Pinching. Snip off manjari as they form and nip each stem tip above a leaf pair. The plant branches out instead of going to seed, and lasts longer.
• Harvesting. Take leaves from the tops of stems. Stripping the lower stems leaves a bare, woody plant.
• Feeding. A small handful of vermicompost every five to six weeks from March to October. Rich nitrogen feeds push soft, green, aphid-prone growth.
• Repotting. Move up one pot size each year in February–March or at the start of the rains. It does well alongside other medicinal herbs to grow at home that like the same sun and drainage.

How long does Krishna tulsi live, and how do you grow more?

Like all holy basil, it is a short-lived perennial. A pinched, well-lit plant usually stays productive for two to three years before the stems turn thick and woody. To keep the line going:

• From seed. Let one or two manjari ripen and dry on the plant, then sow the tiny black seeds on the surface of moist soil in spring or early monsoon. Most seedlings carry a purple tint, but the depth of colour varies from plant to plant.
• From cuttings. Root 10–15 cm tip cuttings in moist, sandy soil during the monsoon. A cutting is an exact copy, so take one from your darkest plant.

Black tulsi through the Bengal year

Our plants grow in the warm, humid Kolkata climate, and these timings suit most of the eastern plains.

February to April: growth returns. Fresh purple shoots appear. Repot, add compost and start pinching. Many homes hang a dripping earthen jhara over the mancha through Boishakh.

May to June: peak heat. Water early. On an open roof, a little afternoon shade protects young plants from scorch.

July to September: the monsoon. Leaves often turn greener under cloud, and soggy soil is the main threat. Raise the pot, water only when the top layer dries and trim back any stretched stems.

October to November: Kartik. Clear skies bring back the deep colour just as the evening lamp is lit beside the plant each day of Kartik. The month closes with Tulsi Vivah.

December to January: the cool months. Growth slows. Cool nights often deepen the purple, but cold, wet soil causes leaf drop. Water sparingly, and in north India move the pot against a warm wall and cover it on frosty nights.

What pests and problems affect black tulsi?

• Leaves dropping in winter. Cold roots in wet soil. Water less, give it the warmest sunny wall and wait for spring.
• Stems blackening and wilting in the rains. Stem or root rot, which looks different from the plant's natural dark colour: rotting stems are soft and limp at the base. Cut them out and repot into drier, sandier mix.
• Curled, sticky or mottled leaves. Aphids, whitefly or tulsi lace bug on the undersides. Spray neem oil every week until they clear.
• White, cottony tufts. Mealybugs in the leaf joints. Wipe them off and follow with neem oil.
• Chewed or rolled leaves. Caterpillars or leaf rollers. Remove them by hand.

What does Krishna tulsi mean in tradition and Vastu?

In many Hindu homes, black tulsi is offered in worship and kept beside the green plant, its dark colour linked to Krishna. Families light a lamp near it through Kartik, and the season ends with Tulsi Vivah, when the plant is ceremonially married to Lord Vishnu. Vastu tradition usually places tulsi in the north, north-east or east of a home, or at the centre of the courtyard, and it appears on almost every list of the best vastu plants for home. These are traditional beliefs, not claims about what the plant does.

The leaves also go into tea and kadha in many households and have a long history in Ayurveda. That is tradition, not medical advice. Please consult a doctor before using any herb as a remedy, especially during pregnancy or alongside regular medication.

Is black tulsi safe around children and pets?

It has no thorns or irritating sap, and children can help water and pinch it. The ASPCA lists sweet basil as non-toxic to dogs and cats but has no separate entry for holy basil, so we do not class it as pet-safe. Keep pets from chewing it.

What grows well beside black tulsi?

A small courtyard herb corner suits it well. Add green chiretta, another courtyard herb which tolerates a little more shade, and an asgandh plant for the sunniest ledge, which likes it even drier than tulsi does. For more ideas, this guide to plants for home garden with their names covers flowers, fruit and herbs for Indian gardens.

Bring home a Krishna tulsi before Kartik

Order this week and your plant can settle in and colour up before Tulsi Vivah. Every plant is raised and packed at our own nursery in West Bengal. Check the cities and towns our tulsi plants travel to, then give your new plant the sunniest spot you have.