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Growing Lemongrass Hydroponically – A Full Guide

Introduction to growing Lemongrass hydroponically: Lemongrass (Cymbopogon citratus) is a shrub-like herb with a different lemon aroma and flavor. The hydroponics system is a method of growing plants in a water-based nutrient-rich solution. The advantage of growing Lemongrass in hydroponics is that the procedure is clean, with faster growth and edible roots. Plant roots are always cut off when grown in soil whereas; the entire roots can be consumed.  Growing Lemongrass hydroponically provides you with complete control over nutrient intake, and fewer risks of encountering soil-based pests and diseases. In this article we also discussed the following topics;

  • Hydroponic Lemongrass growing conditions
  • Hydroponic Lemongrass nutrient requirements
  • Hydroponic Lemongrass growing medium
  • Optimal pH for Lemongrass growing hydroponically
  • Advantages of growing Lemongrass in hydroponics

A step by step guide to growing Lemongrass hydroponically

The hydroponics refers to the practice of growing crops without soil, with the plants receiving their nourishment from water instead. In contrast to soil-based agriculture, where the plants are fed by extracting nutrients from the soil, the roots of hydroponically grown plants are a complete liquid plant food that contains all the nutrients the plants need.

A hydroponic system will use less water than soil-based plants because the system is enclosed, which results in less evaporation. Roots expand and spread out in search of foods, and oxygen in the soil and this is not the case in the Hydroponics, where the roots are sunk in a tank full of oxygenated nutrient solution and directly contact with essential minerals. This means you can grow plants closer, and consequently huge space savings.

In place of soil, hydro systems use a medium to anchor the plants, such as rock wool, coconut fibers (known as coir), or perlite. Other systems have no solid growing medium, with the roots bathing directly in the liquid. The general thread tying all hydro systems together is that the plants are receiving fertility from the nutrient solution, rather than soil.

Conditions for growing Lemongrass hydroponically

Lemongrass is a popular hydroponic herb and grown commercially for fresh harvests. Lemongrass seeds germination rapidly within 3 to 5 days at 77 to 86°F, making this an easy plant to establish. Mature Lemongrass plants can become as large as 4 ft. in diameter with leaves 3-ft. long, although small plants can be grown if kept well-trimmed.

Even the foliage of young seedlings have the fresh pungent flavor of Lemongrass, so harvesting can take place as soon as there is sufficient foliage to cut for use. The use of small rooting volumes such as nutrient film technique is not recommended due to the large and fibrous root system that rapidly develops and causes system blockages and slows the flow of nutrients.

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Growing Conditions for Hydroponic Lemon Grass.
Growing Conditions for Hydroponic Lemon Grass.

Lemongrass requires warm temperatures to produce well and develop a strong and distinctive flavor; it will survive cool conditions in a dormant state. The optimal temperatures range is 72 to 95°F, with a high humidity level (more than 80%) and full sunlight or high levels of artificial light. Full-spectrum grow lamps are recommended for several spices such as Lemongrass as there is evidence to suggest certain parts of the light spectrum that are UV assist with the development of flavor compounds in plants.

Low-to-medium Electrical Conductivity (EC), a measure of nutrient strength, is normally preferred, with an EC range of about 1.2-1.8, and a slightly acidic pH level of about 5.8 to 6.4 will be ideal for most culinary herbs.  Economical and easy to use pH pens and EC meters are obtainable for precise measurements of these important aspects of hydroponic growing.

Requirements for growing Lemongrass hydroponically

Considerations for growing hydroponic herbs contain light, nutrients, temperature, humidity, and pH level. Once these factors are controlled, hydroponics provides a less time-consuming and growing medium versus conventional soil.

While propagating Lemongrass from cuttings is a viable option, starting your herbs from seed is the most popular method for growing hydroponic herbs. Moistened propagation cubes work well for seedlings, as does a conventional soil mix. Germination typically takes 1 to 3 weeks. Once the seeds are of adequate size and are displaying their true leaves, the plants can be transported to your hydroponic growing system.

Herbs need at least 6 hours of bright, unobstructed sunlight per day. A south-facing window can provide adequate lighting for herbs. Rotating the Lemongrass plant to ensure all sides receive sufficient coverage is advisable. Since Lemongrass plants thrive on up to 10 to 12 hours of sunlight per day, grow lights are recommended for extra supplementation, especially if plants are not receiving the minimum natural sunlight to remain healthy. Standard fluorescent lamps can be sufficient, but their yield is less effective compared to modern LED grow lights. High-intensity discharge lights [HID] are effective especially metal halide, which is superior for growing leafy herbs. Since grow lights with blue spectrum lighting encourage lush, bushy growth in Lemongrass, grow lights with blue spectrum capability may be the best choice to grow your hydroponic herbs.

Water and nutrients for growing Lemongrass hydroponically

A good quality hydroponic nutrient formulation is very important. Most herb plants prefer low to mid electrical conductivity levels (1-1.6) and total dissolvable salt levels of between 800 and 1200 ppm (measuring total salts is a way to ensure correct nutrient levels). A slightly acidic pH level between 5.5 and 6.4 is ideal.

Nutrient solution for hydroponic Lemongrass

Hydroponic growers can choose from a variety of commercial nutrient solutions or also make their solutions. One common nutrient recipe combines ½ ounce of potassium phosphate, 2 ounces of potassium nitrate, 3 ounces of calcium nitrate and 1 ½ ounce of magnesium sulfate dissolved in 25 gallons of warm water. This recipe requires ½ pint each of iron sulfate, boric acid, and manganese chloride, as well as ½ teaspoon of zinc sulfate and copper sulfate to give important micronutrients. Because plants exhaust the nutrient solution over time, changing the solution every 3 weeks is necessary to prevent damage to the plants.

Growth media for hydroponic Lemongrass

You can grow Lemongrass hydroponically using several kinds of growth media, including sterile root cubes made from peat and vermiculite or cellulose fiber. These help to support the Lemongrass plants. It is possible to grow herbs hydroponically directly in a nutrient solution, but most require some kind of physical support. Avoid using peat pots or growth cubes produced for non-hydroponic gardening as they tend to disintegrate and may clog your hydroponic system.

Lemongrass propagation in water

Propagating a Lemongrass is as easy as placing the stalks in a glass of water and hoping for the best. Lemongrass can be mainly found in most Asian grocery stores as well as some larger supermarkets. Buying Lemongrass for propagation, pick stalks that have the bottom bulb still intact. There’s a chance there can be some roots still attached and this is even better.

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Suitable hydroponic system for growing hydroponic Lemongrass

Deepwater culture hydroponics

A deep water culture hydroponics system is a method of growing plants hydroponically while the roots are suspended in a nutrient solution throughout the entire grows cycle. A net pot is suspended from the center of the lid; the roots are suspended in the nutrient solution, in a reservoir under the lid containing the nutrient solution. Air is pumped into the reservoir with the use of an air pump. This keeps the water supplied with the amount of oxygen needed for the plant roots. The grow pot is filled with a growing media such as gravel, clay pellets, lava rock, etc. it is suspended in the nutrient solution. The key to fast growth is making sure that when the plants are in their young stage the roots are at least touching the water. As the Lemongrass plant grows and you see signs of roots growing down into the water you can now drop the water level.

Ebb and Flow hydroponics

Ebb and Flow is a method of growing plants hydroponically that is known for its reliability, simplicity of operation and low cost of investment. Pots or a flood tray are filled with a growing media such as gravel, clay pellets, and lava rock, etc. These do not function such as soil or add nutrition to the plants but will anchor the plant roots and will function as a temporary reserve of water and nutrients. The hydroponic solution floods the system 4 to 6 times a day and is allowed to drain away in between flood cycles.

With this system, a watertight flood tray or pot, containing clean gravel, clay pellets or lava rock is used as the rooting medium. The hydroponic system is then periodically flooded for short periods (5 to 15 minutes) with a nutrient solution pumped from a reservoir. By locating the reservoir below the flood tray, with an overflow drain, the nutrient solution can drain back by gravity through the pump with the same line that supplied the water during the flood cycle. Good media is lava rock with this type of system. Lava rock drains quickly and traps air and will not leave a clay residue if using clay pellets, which can clog the pump after time. Lava rock contains slight trace minerals that are beneficial to the plants.

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In an ebb-and-flow system, the plants are held in plastic pots in a flood table, and the reservoir is underneath. A timer clicks a submersible pump on, flooding the roots with nutrient-rich water and waste gasses. When the timer clicks off, the water drains back to the reservoir, pulling fresh oxygen to the plant roots. The timer is generally set to flood three to four times per day, with 15 a minute duration per flood.

Rooting Lemongrass in water

To encourage Lemongrass stalks to grow new roots, place them bulb down in a jar with an inch of water in the bottom. Rooting Lemongrass in water can take as long as three weeks. Throughout that time, the tops of the stalks must start to grow new leaves, and the bottoms of the bulbs should start to sprout new roots. And to prevent the growth of fungus, change the water in the jar every day. After 2 or 3 weeks, Lemongrass roots should be an inch or two long. Now you can transplant them to a garden or a container of rich, loamy soil. Lemongrass prefers full sun and it can’t tolerate frost, so if you experience cold winters, you’ll have to grow it in a container or treat it as an outdoor annual.

Benefits of growing Lemongrass hydroponically

Outdoor plants are subject to many variables, such as temperature, precipitation, and lighting. Since Lemongrass thrives in a mild, consistent and controlled environment, indoor hydroponics is a preferred method of growing.

Overwatering and under watering is a constant challenge with soil mixes. Too much or too little water can result in the demise of your herbs. In contrast, hydroponic allows for a consistent supply of water and nutrients, eliminating the stress and guesswork involved with growing herbs in the soil.

Not only will you avoid the mess caused by having a soil mix, but growing Lemongrass using hydroponics can also result in a 20%-50% faster growth rate.

Pests love soil. Gnats, flies, and other insect infestations can be a constant problem for those who use a soil mix to grow their Lemongrass plants. Since the hydroponics system uses no soil, this becomes less of a concern. No soil-borne diseases, no weeding, and the need to introduce those insecticide sprays into the indoor environment are less likely.

Importance of supplying air and oxygen (O) in hydroponics

The importance of supplying the right amount of air and oxygen (O) when growing plants with a deep water culture or ebb and flow hydroponics system.

Almost half of the total dry weight of a plant is made up of oxygen and this means you need a proper and even air delivery system when growing with a hydroponics system. With the absence of oxygen, which is a necessary element disintegration of plant tissue soon accrues. During warmer temperatures and an increase in oxygen level is much appreciated by the plant versus cooler temperatures.

Plants obtain oxygen in the elemental state from the atmosphere, this enters through the stomata, along with the oxygen that enters through the plant roots in water is termed external oxygen. Oxygen is also liberated during the process called photosynthesis. This additional supply of oxygen is supplied within the Lemongrass plant, this is termed internal oxygen.

Without an adequate oxygen supply, it is not possible for the oxidation of organic substances in respiration to take place. During normal conditions, the atmosphere contains 21 percent oxygen, but the air in your grow media is lower due to the proximity of the roots and the root mass. In this, the oxygen level can drop as low as 18 percent. A fall of this few percent will have inhibiting effects on the plant’s growth rate and overall plant health.

The importance of ensuring that the plant roots receive the appropriate amount of oxygen cannot be stressed enough when growing with a hydroponics system. Lack of oxygen interferes with the respiration of the protoplasm of the root cells causing wilting. This can be present as yellowing and or brown spots on the leaves, the plant does not look healthy in mild cases, but you are not sure what to do. Start by making sure you have the suitable air delivery to the roots of the plant, whether you are growing with an ebb and flow or deep water culture hydroponics system.

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