Medicinal and Aromatic Crops

Cultivation

Soil

C. forskohlii thrives better in well drained soils with a pH ranging from 5.5 -7.0. It does not require very fertile soils and can be economically grown under marginal soils.
Climate
Coleus is a crop of the tropics and is found growing well at an altitude of about 2400m under tropical and sub tropical conditions. It grows well under humid climate with a RH ranging from 83-95% and a temperature range between 10-25O C for its successful growth.
Varieties
A selection, K-8 is reported to give 0.5% forskolin and a higher tuber yield. A new variety ‘Aisiri’ with forskolin content of 0.7% released from UAS, Bengaluru.
Propagation and planting

Coleus is propagated by terminal cuttings. Normally, 10-12 cm long cuttings comprising 3-4 pairs of leaves are preferred. These cuttings are either rooted in nursery and then planted in the main field or planted directly in the main field.
The ideal season for planting Coleus is from June to July with the onset of South west monsoon. Before planting, the field is ploughed deep soon after the receipt of pre monsoon showers and brought to fine tilth. The crop loves high amount of organic manure and about 25 t FYM/ha is applied. Ridges and furrows are prepared at 60 cm spacing. The height of the ridge should be 15 cm from ground level. The cuttings are planted at 30 or 45 cm distance depending on the soil type. While planting, care should be taken to see that minimum of two nodes should be underneath the soil. Watering should be done before and after planting.
Under drip irrigation system, raised broad row ridges of 90cm width are prepared at 60 cm interval and planting at 60 cm spacing between rows are planted. The space between two plants should be 45 cm.

Manures and Fertilizers
The crop requires plenty of organic manure. In addition to 25 tonnes of FYM, addition of 1 ton vermicompost, 150 kg of neem cake, 500 kg of gypsum are applied to condition the soil and to improve its fertility by organic means. Many farmers adopt organic farming by avoiding chemical fertilizers and pesticides. ‘Panchagavya’ 3% organic spray is given along with root drenching.
A fertilizer dose of 40 kg N, 60 kg P2O5 and 50 kg K2O per hectare is recommended for Tamil Nadu. Half the dose of N, the whole P and K may be applied as the basal dose followed by the remaining half N, 30 days after planting as top dressing.
Irrigation
The first irrigation is given immediately after transplanting. In the initial phase, the crop is irrigated once in three days and there after, weekly irrigation is enough to obtain good growth and yield.
Weeding and earthing up
Two or three weedings are given and after the second weeding, earthing up is given. As the roots are shallow, deep digging should be avoided.