Krishna Tulsi is a tropical plant but it still dislikes direct sunlight. So, do not keep your basil plant at a spot where the sun is beating down. Indirect sunlight is best for basil plants.
Tulsi plant likes lots of moisture in the soil. So you need to water it at least 2 times daily in summers and once in winter. If the basil plant is out in the sun, then it needs more water than the indoor plants.
Basil needs soil that can retain moisture. That is why black soils with high amounts of clay matter are good for tulsi plants. The most basic thing you must know to care for basil plants is that they need to be in a moist soil that can keep them well supplied with water for many hours.
The plant doesn't need much fertilizer but if you want aromatic basil, then you need to give organic manure.
Once the basil plant starts sprouting flowers, not only it will its leaves lose the flavour but it will also stop growing. Prune the flowers as soon as they appear.
Holy basil is an erect, many-branched subshrub, 30-60 cm (12-24 in) tall with hairy stems. Leaves are purple; they are simple, petioled, with an ovate, up to 5 cm (2.0 in)-long blade which usually has a slightly toothed margin; they are strongly scented. The purplish flowers are placed in close whorls on elongate racemes
Superb as a container herb plant on the patio or you could try growing basil on the kitchen windowsill and in convenient containers outside the back door.