It is more than feasible to grow herbs indoors almost all year round. In fact, it is no more difficult to grow them indoors than growing them in the garden provided there is enough light. Essentially they need the same conditions. Sunlight and well-drained soil.
If possible you should select a south facing window. Most herbs need sunny conditions and south facing will be best. In winter, a fluorescent or “grow lamp” would be a good idea.
When planting your herbs you need two parts sterilized potting soil to one part coarse sand (or perlite). Add in 1 tsp of lime to each pot. The pots themselves should have one inch of gravel (small stones will do) at the bottom to ensure adequate drainage.
As with growing outside, you need to consider the individual needs of the herbs. When plants are in full growth they will need more water than at more dormant times. However, you must make sure that you don’t overwater. Waterlogged roots are a surefire way to kill the plants off. Ideally, keep the pots on a tray of pebbles, mist the herbs, and keep the pebbles moist.
Perennial herbs will appreciate a move outdoors during the summer. They won’t die if you don’t but you will see better and stronger growth if you do. Simply pot the pot up to it’s rim in a suitable location within the garden. Obviously when the weather starts to cool, you need to make sure that they are brought in before the first frost is forecast. Annual herbs can spend the full year cycle indoors.
An indoor herb garden can be pretty much maintained indefinitely providing, they get lightly fed periodically, get repotted yearly, and watered as necessary.
Fresh leaves may be picked as soon as the plant has enough foliage to maintain growth. The best time to harvest your herbs is in the morning after the dew has disappeared, and before the sun has become too hot. To ensure good oil content, pick leaves or seeds after dew has disappeared but before the sun becomes too hot. For dry, winter use, harvest leaves before the flower buds open. Pick the seed heads as the color changes from green to brown or gray. Wash dirty leaves and seed heads in cold water; drain thoroughly before drying.
