Indoor lights are the key component of growth for hydroponic plants. Light is the catalyst for photosynthesis, the driving force behind most of the green plant life on our planet. The process of photosynthesis uses the energy from light to convert water and carbon dioxide into carbohydrates and oxygen. These elements are used by the plant as food necessary for growth and sustenance.
Fluorescent lights are adequate for plants that do not need much sunlight, but will not help produce anything other than greenery. Natural sunlight is not white, but is made up of many colours. Bending light will expose a dazzling array of red, orange, yellow, green, blue, indigo and violet beams. To really imitate natural sunlight, a range of bulbs that represent the colours of the spectrum will provide the best hydroponic plant growth.
For an indoor hydroponic garden, the grow light should come from the red and blue beams. This kind of light, called PAR (photosynthetically active radiation), is the next best thing to natural sunlight.
High Intensity Discharge (HID) lights are designed for hydroponic use. They are stronger than regular fluorescent lights and provide the maximum amount of PAR for the amount of wattage. There are two types of HID lights:
- Metal Halide from the blue/white spectrum
- suited for vegetative growth, including plants such as lettuce, basil, herbs, house plants, etc. This means the metal halide grow lights are not best for producing flowers.
- High Pressure Sodium from the orange and yellow part of the spectrum.
- promote bud growth and flowering
- suited for tomatoes, peppers, cucumbers, flowers, flowering house plants or other types of fruit bearing plants
Choosing a type of grow light is a decision that should be based on what kind of plants are going to grow in the environment and the results that are expected. Seeds or cuttings will grow under either category of lights. MH/HPS conversion bulbs are available which allow switching back and forth with ease. If these two types of grow light systems are combineda dual spectrum combination grow system will mimic the natural sun and is suitable for year-round growth of fresh berries, vegetables and herbs, as well as beautiful flowers.
Hydroponic light is measured by wattage per square foot. Photosynthesis will occur if the wattage is around 20 watts per square foot for low light plants and as high as 50 watts per square foot for vegetation that needs a higher intensity.
The tips of stems and tops of leaves can become scorched if the hydroponic lights are too close to the plants. If the wattage is low or 250W, the bulb should be 12-14 inches away or 16-24 inches from a 400W bulb and have 24 inches between the plant and a 1000W light.
The colour of paint on the walls and ceiling makes a difference too, with lower gloss white paint making the most of your indoor lights. Mylar is even more reflective if you want to get serious and don’t mind the look.
Hydroponically grown plants need roughly 16-18 hours of light per day for normal growth. Some plants need extra light followed by a period of darkness in order to force blooms to flourish inside. Timers can be purchased to help alleviate the need to remember the lighting cycle and to allow you some freedom from your light switch.
Using HID lights extends the growing season in the fall and allows a head start in the spring, but don’t get too carried away! Extending the light beyond 18 hours a day will wear your plants out and cause an untimely demise.
There are many advantages of the different indoor grow light options available, including:
|
Fluorescent Grow Lights |
High Density Discharge (HID) Grow Lights |
Metal Halide (MH) Grow Lights |
High Pressure Sodium (HPS) Grow Lights |
Dual Spectrum Combination Grow Lights |
| Fluorescent lighting is primarily used for seedlings and cuttings | High Density Discharge lights include two varieties:
1. Metal Halide (MH)*, which emits white/blue spectrum and is best as primary light source 2. High Pressure Sodium (HPS)*, which emits yellow/orange spectrum and promotes flowering * Additional information provided in other areas of table |
Metal Halide light is primarily used for plants in the vegetative stage | High Pressure Sodium light is primarily used for plants in the flowering stage | Combination grow light systems maximize plant development and growth with a dual spectrum lighting system, delivering the only full-spectrum plant lighting |
| Fluorescent lights and low in intensity and emit a low temperature, making them the perfect choice for young plants.
T-5 fluoresent lighting systems are by far the brightest and offer the best spectrum for indoor growing. They can be used for starting seedlings and clones and the larger systems can be used all the way up to harvest. |
Most Efficient, and most intense with wavelengths of light and HID designed specifically to cover both spectrums of natural light: Red: most pronounced in fall Blue: most pronounced in summer |
One of the best sources for plant growth, emitting white/blue – best as primary light source | High pressure sodium lighting systems produce a red/orange spectrum, perfect for promoting rapid fruiting, flowering and budding | This type of hydroponic lighting system blends the blue spectrum of a metal halide lamp with the red spectrum of a high-pressure sodium lamp, offering the best of both lighting systems |
| If you are growing where some natural light is available (in a sunroom, for instance), fluorescent lighting may provide enough supplemental light for all stages of growth | If only going to use one type, this would be good choice | MH to HPS and HPS to MH conversion bulbs available | The most advantageous hydroponic lighting for all stages of growth. | |
| Adequate for propagation | MH to HPS and HPS to MH conversion bulbs available |