For many, indoor gardening is an exciting hobby, one which often leads to the possibility of setting up a profitable business using new skills and knowledge. While hydroponics is the basis of many successful commercial enterprises, selecting the right crop is essential and, given the high intensity, but limited area of many indoor gardens, niche market crops are usually a good option.
Crops that currently receive the highest returns on local markets include those such as ginseng, bay, tarragon, and saffron, all of which are suited to both hydroponics and indoor cropping. While a high rate of return per pound may look lucrative, growers also need to take into account the difficulty of the crop, yields per square foot, time to harvest, and availability of information on hydroponic cultivation.
Some of the most highly priced, niche crops are relatively low yielding and slow to mature, so growers need to weigh up all these factors before deciding which to grow.
French tarragon (Artemisia dracunculus) has long been a staple hydroponic herb and is relatively easy to grow. It is a perennial bushy plant with slender branching stems and smooth olive green, narrow leaves. The flavor of tarragon is strong, sweet, aromatic, and reminiscent of anise and licorice and has been growing in popularity as a culinary flavoring.
While French tarragon does receive considerably higher prices per pound than most other herbs (currently around $16/lb), it is slow to produce good yields and can take up to a year before regular harvests of fresh cut product can be taken and the foliage is light in weight.
French Tarragon, being a long-lived perennial plant, is suited to free draining media bed systems with substrates such as perlite as the plant is intolerant of high moisture levels. A warm, well-lit environment is required to prevent tarragon plants going into dormancy which halts growth and, in an indoor garden, tarragon can be grown year round.
Tarragon has similar nutritional requirements to other slower growing herbs such as rosemary and thyme, with an EC of 1.6-1.8 for mature plants and 1.0-1.2 for young plants, cuttings/root divisions, or plants just coming out of dormancy.
Bay leaves, sold both fresh and, more commonly, as a dried product, are produced by the Bay tree (Laurus nobilis) a native of the Mediterranean region where it can reach heights over 40 feet. Under hydroponic cultivation for fresh herb production, young trees are regularly trimmed to restrict height. Fresh bay leaves currently receive around $30/lb and are used to flavor a wide range of dishes.
Bay is a slow-growing tree, best suited to being individually planted into containers with a drip irrigation system. Small plants are generally started as cuttings and potted on as they grow in size. The growing point of young plants needs to be removed to encourage branching and stem development for higher yields of individual leaves as the plants grow to a harvestable stage.
Bay trees are fairly hardy and can survive cool conditions, but for maximum growth, they do best in a warm, dry, high-light environment with EC levels maintained in the 2.4 – 2.6 range. While bay is relatively disease free, it is prone to attack by mealy bugs which can either be manually removed for small plantings or sprayed regularly with neem oil.
American Ginseng (Panax quinquefolium L.) is a relatively new crop to hydroponic production and one which has considerable potential to increase both yields and quality of the harvestable product. Dried ginseng root is reported to receive around $500-$600 per lb, however the plant is slow growing and low yielding compared to most other fast turn-around hydroponic crops.
One of the main advantages of ginseng is that it must have a very low light, cool environment and is thus suited to indoor production where these factors can be easily controlled. American ginseng is native to the cool, shady hardwood forests of eastern US and Canada and since the 18th century, has been hunted down and dug from the wild to supply markets, often exported to Asia.
However, the high prices and demand for ginseng combined with its slow rate of growth and reproduction has meant that wild populations are often dug at an early age before flowering and seed production has occurred, thus the plant faces extinction in the wild. Due to the high prices paid for wild ginseng, cultivation of this crop has become more widespread with most systems still being soil based.
Cultivated plants are a long-lived crop, with the roots becoming larger each year until harvest, often in the fourth year — at this stage roots are usually forked and around four inches long and one inch thick. Mature plants are between one to two feet tall and enter into a dormancy phase in autumn when the leaves turn yellow and stems die back.
Propagation of ginseng is somewhat time consuming as the seed requires at least 12 months of after-ripening (stratification at low temperature) before germination will occur. However, for quicker crop establishment, growers can start with one- to two-year-old roots which are precisely spaced to maximize plant density in the growing area. While starting a crop from young roots is more expensive than raising planting stock from seed, it reduces the time to harvest and allows only healthy roots to be selected for planting out.
A potentially profitable option for indoor hydroponic growers with limited space is to not grow ginseng for harvest of the mature product (which then needs to be carefully dried before sale), but to propagate from seed and sell only one- to two—year-old roots to other growers. Ginseng seedlings can be grown at a much higher density than mature plants and respond well to hydroponic nutrition — this allows the production of high-health planting stock which has not been in contact with soil and is well suited to further soilless production.
Starting with stratified seed which is usually for sale in fall, this needs to be sown a half-inch to one-inch deep, with an average germination rate of 70 per cent. Seed beds containing a mix of fine grade perlite and coconut fiber and a high-quality, low-mineral water source are suitable for the germination process
Hydroponic Systems for Ginseng
Hydroponic systems for ginseng have had limited research, however, there is potential to improve yields and growth rates through climate and root environmental control as well as optimal nutrition. Ginseng requires low light levels (heavy shading is used for outdoor crops) with light saturation occurring in both seedlings and mature plants at about 150 micromoles m-2 s-1 (1) which is around 7.5 per cent of full sunlight. Too much light will reduce yields, burn leaves, and lead to plant decline, while excess shade depresses the yield potential. Much of the photo assimilate produced by the ginseng leaves ends up in the thickened root system, however, the yield of the roots can be increased by up to 25 per cent if the flowering stems are removed as they form.
Temperatures for ginseng are similar to those for other cool-season crops, around 68-73°F (20-23°C). Growing mediums for ginseng must be free draining, but at the same time not impede the development of the forked roots — coconut fiber, or mixtures of fiber and perlite under drip irrigation are suitable.
Overly wet substrate conditions should be avoided as these attract fungus gnats, the larvae of which can damage the roots and introduce infection. Some research has also indicated that for high quality root production, ginseng can be grown aeroponically without the requirement for any growing medium. Spraying roots for 30 seconds every 10 minutes in the light period, and for 30 seconds every 30 minutes during the dark has been stated as a suitable frequency. Ginseng can be prone to root rot and physiological disorders, so the use of disease-free root stock is recommended along with high quality water sources and solution disinfection.
There is little information on suitable nutrient ratios or elemental levels for hydroponic ginseng, however, a low EC of 0.5-1.1 has been suggested for solution culture system. A high concentration of potassium has also been stated to result in an increase in ginseng root growth.
Harvesting ginseng roots at the end of the growth period occurs when they have reached a fresh weight of around an ounce. Harvesting needs to be carefully carried out as damaged roots receive lower prices than intact ones. After harvest, substrate grown roots need to be washed then dried in drying rooms with forced air to ensure mold growth does not occur. Once dried, roots can be packed and stored until sold.
Profitable hydroponic crops for indoor growers are worth a little investigation into market prices and cultivation techniques, taking into account yields, growing space, and time to maturity. However, many opportunities and a diverse range of crops exist within niche markets, even if some trial and error may be needed to perfect a new commercial enterprise.