There are many different kinds of herbs and most of them can be grown indoors. Varieties that don't do well indoors include horseradish and fennel. Meeting the requirements of an indoor herb garden can be challenging. Herb gardens need light, water, fertilizer and humidity whether they are indoors or outdoors, so proper preparation is a must. Many people have successfully grown their herbs indoors with time and special care.
Mix two parts sterilized potting soil with two parts coarse sand to make the soil to fill your containers. Place 1 inch of gravel at the bottom of the containers and fill the containers with soil, leaving ½ inch to an 1 inch at the top for watering. Add 1 tsp. of lime per 5-inch container. Adjust the lime to the size of your container. Mix the lime into the soil.
Place the containers on a tray filled with pebbles. As you water the plants the draining water will fill the tray and ensure humidity to the plants. Do not allow the containers to sit directly on the water. Alternatively, install a humidifier near the plants.
Water the herb plants when the soil starts to dry on the surface. Young growing herbs, herbs in clay pots and hanging baskets will need a little more water than older plants or those in plastic containers. Do not over-water (soil should be wet but not soggy) and do not water the foliage.
Locate the plants in a sunny south or southwest window where they will receive at least six hours of sun a day. The room should be at least 65 to 70 degrees Fahrenheit during the day and 55 to 60 degrees at night. Rotate the containers every few days to ensure straight growing plants.
Feed the herbs every two weeks with fish emulsion or a water soluble fertilizer. Follow the manufacturer's directions on the amount to use per age and size of the plants.
Provide the plants with proper air circulation by placing a small fan nearby or using a ceiling fan every few days. Plants that need extra humidity also need good air circulation to keep fungus and mold from damaging them.