Greenhouse Methods for Herbs

Planting

• Greenhouses allow growers to begin the cultivation of plants from seeds, plugs and plant trimmings. Hartley Botanic recommends sowing seeds of annual and biannual herbs in the spring and planting trimmings from perennial herbs also at this time of year. For example, mint and basil should be grown from trimmings to ensure the best flavor and consistent appearance.

  In the fall, plant herbs, like chervil and coriander, using trimmings for an uninterrupted supply of these herbs.

  Move dill, chives, thyme and tarragon from the outdoor garden to the greenhouse at the first chance of frost. Consider also relocating parsley, anise and cumin to a warm, moist greenhouses when temperatures start to drop. Think of the greenhouse also as a way to protect herbs during the winter months. It saves money in having to buy new plants in the spring. The warm, humid conditions of the greenhouse should continue to provide fresh herbs for meals all year long.

Growing Conditions

• The same applications for growing herbs outdoors apply to herbs grown in greenhouses as well. Specific herbs require different growing conditions. For example, grow mint in beds rather than pots to allow enough room for its roots to spread. Plant rosemary and sage in pots to control the soil's moisture. These plants do not need as much water as other herbs. Use a balanced fertilizer of equal components to allow for growth and flavor. According to May Hill Press, most herbs grow best in temperatures ranging from 70 to 80 degrees Fahrenheit with humidity of 40 to 50 percent. The greenhouse provides a controlled environment that allows growers to regulate its temperature.

Cropping

• Most herbs take from 60 to 90 days to harvest in a greenhouse. An exception is basil, which can take 40 days to cultivate. Crop them as soon as they become established, according to "Growing Edge" magazine. This makes the plants bushier as the herbs re-grow.

  In general, it takes three weeks after cropping for herbs to re-grow. Chives and thyme take longer to establish than other herbs, taking as long as six months.

  Crop herbs regularly as the constant conditions of the greenhouse allow them to grow faster than they otherwise would grow outdoors.