Cilantro growing indoors needs more nutrition because the root system range is limited and can’t access as much soil for nutrients as it would in your garden.
The soil when planting cilantro indoors should be a mixture of potting soil and sand to allow water to move freely. In addition, you can use a fertilizer of liquid fish emulsion or chemical formulation of 20-20-20 to add additional nutrients. Use half concentrations of the fertilizers bi-weekly during the active growing periods.
Thorough watering is more important than frequent watering when growing cilantro inside. Water the plants until the water comes out the drainage holes. Check the soil frequently, but cilantro growing indoors should only be watered when the soil is dry to the touch. This will be more often in the summer months.
To grow cilantro indoors, it’s important that the plant have full sun four to five hours per day. If you also use a growing light, growing the cilantro inside will be more successful.