I am planning to grow ginger in hydroponics. Can you please let me know which nutrients I should provide for the crop, and how I should go about adding these nutrients to the system? Also, w hat type of yields should I be expecting? Finally, I would also like to know how many nutrients should be used for feeding a 10-foot long by 1 foot wide area of ginger in a drip irrigation system. Many thanks!

Ginger grows extremely well in hydroponics and there have been a number of research trials investigating the best methods of production as well as plant nutrition. A good hydroponic growing medium to use would be deep bags (at least 1-foot deep) or containers of perlite mixed with coconut fiber with nutrients drip irrigated on several times a day and allowed to fully drain between nutrient applications.

The nutrient solution for ginger should contain the following approximate levels of elements:

• nitrogen 170 to 180 parts per million (ppm)
• phosphorus 110 to 120 ppm
• potassium 200 to 240 ppm
• calcium 220 to 230 ppm
• magnesium 40 to 55 ppm
• iron 4 to 6 ppm
• manganese 3 ppm
• zinc 0.25 ppm
• boron 0.70 ppm
• copper 0.07 ppm
• molybdate 0.06 ppm

The ideal EC is 2.5 and pH should be within the range of 5.8 to 6.2. If you are growing on a small scale you can use hydroponic pre-mixed products like a general purpose grow formulation at an EC of 2.5 for the first two to three months, then switch to a fruiting formulation (higher in potassium and calcium) during the rhizome development stage.

Ginger requires warm growing conditions of 71 to 86°F (21.6 to 30.0°C), with some slight shading under high light. Under these conditions, ginger should produce harvestable rhizomes in eight to nine months. Long day length is beneficial with 16 hours being ideal. The plants will also require hilling or earthing up during development of the rhizomes; in hydroponics this just means adding more growing medium to the top of the grow beds or bags that will help the rhizomes expand upwards and increase size and uniformity of shape.

The yields obtained from hydroponic ginger are dependent on a number of factors, not just the fact that the plants are grown in a hydroponic system. Climate, temperatures, light, size of seed rhizome, cultivar, planting density and length of time the crop has been grown for determine yield more than growing method used. Under ideal greenhouse conditions of temperature (71 to 86°F), day length (16-plus hours), nutrition, watering, and with a good-sized seed rhizome of a suitable commercial cultivars (at least 4 ounces in weight for each seed piece), researchers have obtained yields of between three to six pounds per square foot of greenhouse hydroponic grow bed area after a nine-to-tenth-month growing season (plant spacing was 1 foot between plants and 1.5 feet between rows).

Yields, however, can be lower than this if growing conditions are not ideal or if disease causes rot of the rhizomes before they are harvested. Ginger is prone to bacterial wilt, soft rot and erwinia rot, although starting with a clean hydroponic system and high-quality water helps prevent (but not eliminate) the risk of these. Yield is also dependent on cultivar grown and only virus-free and disease-free seed rhizomes should be planted.

The amount of nutrient solution to apply to the ginger crop depends on the size of the plants; watering will increase as the plants get larger, and also on the growing conditions. Warmer conditions means the plants need more water and nutrients per day, and a higher rate of irrigation is used compared to cooler or more humid conditions. For that reason, it is not possible to give exact volumes of water and nutrients to be given each day; this has to be determined by the grower based on the growing conditions that day, how much water the crop is using under those conditions, and other factors such as the rate of drainage from the growing medium in the beds or bags.

As a general guide with drip-irrigated hydroponic crops, enough nutrients should be applied at each irrigation so that 10% of the volume applied drains out the base of the growing bed or bag (placing a shallow container underneath the drainage holes allows the grower to measure the amount of nutrient solution draining out after each irrigation). The frequency of irrigation needs to be decided based on how damp the growing medium remains between each irrigation. In hot climates with a mature crop, irrigation may be as frequent as six to nine times a day, while very small plants may only be irrigated one to three times a day depending on temperatures and other climatic factors.

–Dr. Lynette Morgan