Tulsi (Ocimum tenuiflorum) is a variety of basil. The small perennial herb features fragrant, green leaves and purple flowers. In India and southeast Asia, the plant is considered holy and is often used for medicinal purposes, including healing tea. For this reason, it is often nicknamed "holy" or "sacred" basil or even "queen of the herbs." It is shorter-lived than the more commonly grown culinary basil, but the general care remains the same as for all varieties of basil.
Choose a sunny, warm location for your tulsi. This tropical plant needs full sunlight in order to grow and thrive. Your holy basil needs at least six hours (and preferably eight) of sunlight per day. Often, these plants are treated as annuals because there is not enough sunlight or warmth for them to thrive during the winter months.
Surround outdoor basil plants with a 2-inch layer of organic mulch to retain moisture and nutrients in the soil and to inhibit weed growth.
Water your tulsi plant frequently but not so much that the soil is soggy. Let the top layer of soil (down to an inch) dry slightly between waterings. Too much water can cause fungus to grow or the plant's roots to rot.
Fertilize your sacred basil plant once every other week with a balanced (10-10-10) liquid fertilizer.
Remove spent flowers immediately after they wilt. This will encourage new blooming. To encourage leaf growth, pinch off the tips of flowers when they sprout. This will create a bushier plant, with more usable leaves.
Bring your tulsi plant inside or cover it with a blanket or tarp if the temperature drops below 65 degrees. These are warm-weather plants and should only be grown outdoors in tropical or subtropical climates.