The soil should be a well-drained light sand to silt loam soil, with a pH of 5.5 to 6.5. The soil needs to be kept moist to hasten germination and to ensure a uniform stand, when plants emerge within two weeks. Mulching is recommended for basil production because it ensures moisture retention, prevents weed growth and keeps the foliage clean from the soil. The most commonly used mulch is black plastic, which encourages an early first harvest by warming the soil in the spring. Basil cannot tolerate drought stress.
Water needs to be applied regularly throughout the growing season to maintain constant growth.
Although basil may be irrigated with a simple overhead sprinkler system, drip irrigation is best. Plants grown with drip irrigation are less likely to develop foliar diseases than sprinkle-irrigated plants because the foliage stays drier. Research has shown that growing basil with drip irrigation and black plastic mulch results in high yields of high-quality, clean leaves. The rates of fertiliser application will depend upon the soil type and the previous crops and fertiliser applications. Over fertilising basil sacrifices flavour for growth.