Catnip grows wild in the mountain areas of North Carolina and many other regions of the United States. Traditionally the plants have been collected from the wild, but it is getting increasingly difficult to find gatherers who are willing to search the mountain regions to locate and harvest the herb. Today catnip is cultivated and grown under contract which has resulted in a more uniform and higher quality crop.
The most important component of all aromatic herbs is product quality. When catnip was collected there was often a mixture of catnip plants of varying maturities and of different ecotypes resulting in a non-uniform product. Gathered material also has many weeds and other extraneous debris. Herb companies and catnip buyers often faced with excess raw product will purchase only the highest quality plants. Thus, increasing catnip quality via cultivation is essential for both maintaining current markets and opening newer ones.
The demand for catnip is clearly not large, but a few farmers in North Carolina are making a profit from producing catnip on limited areas. It is essential for growers to have an established market available before starting production. Our efforts at North Carolina State University have been to assist farmers who have a market for catnip and develop more efficient production practices in the production of a quality product
Catnip seeds germinate rapidly and produce healthy seedlings at temperatures between 20-30°C (AOSA 1986). Seeds are sown into warm plantbeds 60-65 days prior to transplanting, which in North Carolina is generally between March 1 and April 1, in a manner similar to tobacco seeding (Tobacco Information 1989).
Daily management of plantbeds is necessary to produce strong, healthy seedlings. Once the seedlings start to grow they should be thinned to a population of about 430 plants per m2. Any plastic cover on the plantbed should be removed if the air temperature reaches 24°C or higher for two consecutive days during seedling growth to avoid heat damage. Coverings are desirable when the temperatures go below 7°C. Seedlings are ready for transplanting by hand or mechanically when they reach a height of 150 to 200 mm.
Catnip has few insect or disease problems. However, weeds, the major pest need to be controlled by cultivation. There are no herbicides labeled for use in catnip production nor are any expected in the future.
Catnip is ready to harvest when the plants are in full bloom. The aromatic properties of the volatile oils in catnip decrease after this stage making timing of the harvest critical. Plants are harvested by clipping the stems about 10 to 12 cm above the crown. This allows regrowth from the adventitious buds located on the lower stem nodes. The thicker stems of the harvested plants may also be removed to allow for a leafier, finer stemmed and aromatic product. In the Piedmont areas of North Carolina (lower elevations), two harvests can be generally be made in a single growing season. At higher elevations cutting a second time could result in significant plant injury over the winter.
In general a stand of catnip will last for three years, after which time the weeds generally become a serious problem and the stand, yield and quality of the crop decreases. Yields of 4.4 to 6.7 tonnes/ha dry weight can be expected in years when growing conditions are good.