The urban gardener asked:


Along with water,  hydroponics plant nutrients, Co2 and oxygen, grow lights is the key basic component, required by plants to live. Providing additional light is necessary for indoor gardening. Furthermore, light should resemble the sunlight as much as possible. In order to achieve that goal several types of lights are used: incandescent, fluorescent, high intensity discharge or HID lamps and sulfur lights. While there are many other types of lighting, only the mentioned above are recommended for indoor gardening. The major concern with other types of lights is that they do not produce light in the appropriate spectrum, required by plants.

Though typical widely used incandescent lamps fit any ordinary light socket, this type of lighting is considered to be the least effective in lighting your garden in comparison with other types of lighting. Incandescent lights produce light in the red spectrum; that is why such lamps are commonly covered with a blue coating in order to increase the amount of blue spectrum in the produced light. In general, incandescent lights are considered to be poor options for indoor gardening needs.

In comparison with incandescent lamps, fluorescent lights produce more light with lower energy consumption. However, the light, produced by fluorescent lamps, is not intensive enough and cannot penetrate more than 6” – 8”. Light, produced by fluorescent lamps, is usually simply insufficient to provide normal growing of plants, vegetables and flowers. The only application, where it is possible to use fluorescent light, is growing seedlings, cuttings, or some particular plants with low light requirements, such as orchids.

High intensity discharge lights, also known as HID lights, are currently the most effective lights for indoor gardening. Metal halide (MH) and high pressure sodium (HPS) grow lamps are two major types of HID lights. Each type produces light in a particular range: for example, metal halide lights generate blue spectrum light similar to the full summer sun, and high pressure sodium lights produce light in red and yellow spectrum, resembling the autumn sunlight. 

Though high pressure sodium lamps usually are more expensive (by about 10%-20%) than metal halide lamps, they are more durable with extended lifecycle. Besides, HPS lights feature higher lumen output (97-150 lumens per watt consumed) and lose only about 5% of their brightness after one year of use (for comparison, MH bulbs produce about 70-115 lumens per watt and  lose up to 15-20% of their initial brightness within a year). 

Irrespectively to the particular type of lighting in use, it is recommended to replace lights on the timely manner: MH bulbs – after 12-18 months, and HPS bulbs – after 24 months of work. Basically, metal halide lamps is the more preferred type of lighting for plants, when they grow, and high pressure sodium lamps suit best for flowering plants. However, the discussion on which type of lighting is best is still open among gardeners. Each type of lights offers its own advantages, as well as disadvantages, so it is often a matter of personal choice, preferences, growing environment and needs. The scope of this article is to provide plain information on the available types of lighting for indoor hydroponic gardening, while leaving readers enough space for personal decisions on which product to prefer.  By the way, recently a new type of lights appeared. The so-called conversion systems allow switching between MH and HPS lights when it is necessary simply by changing the bulb. Though this type of lighting offers certain benefits, conversion systems are still pretty expensive. More information on particular types of HID grow lights used in hydroponics systems will be provided in the next set of hydroponics guides.

The urban gardener asked:


A great indoor garden requires a good grow light. It could mean the difference between success and failure. Having the right hydroponic light is the single-most important and costly decision in setting up your garden.

 Hydroponic grow lights come in three main types:

 

Incandescent lights

These are the usual lights found in homes. They are generally a poor choice for garden grown lights because of their limited light spectrum and inefficiency.

HID (High Intensity Discharge) grow lights

Producing more light (up to 10x more lumens/watt than an incandescent light),are more efficient. Drawbacks would be, they produce more heat, generally more expensive than incandescent lights and requires the additional expense and maintenance with ballast. It takes around 100 hours before hydroponic HID grow lights reach their optimum working conditions, or until they reach light intensity and color stability. 

Natural Sunlight

Expense for acquiring artificial lights can be skipped by using sunlight. This is done with the use of solar room, greenhouse or large windows which allows plenty of sunlight. Or you can do this outdoors; hydroponics does not necessarily mean the cultivation of plants indoors but it growing plants without the use of soil.

Basic setup for an indoor garden is 1000w of lighting for and area of 16-25 square feet of plant area. Reflectors and/or light movers should also be considered as they improve efficiency of the indoor hydroponic gardening system. Ballast may also be needed as numerous hydroponic grow lighting require igniting.

 Some Basic Facts

Before plugging in your grow light

Different plants require different levels or types of lighting, this paragraph would deal on some simple know-how on how to make an effective lighting setup. In setting up your garden, it is essential that you determine your growing area in order to determine the best lighting setup for you. Light is an essential factor in the growth of plants, it is important that the lighting solution you chose for your garden is adequate for its size. A poor or ill advised decision would certainly reflect on the quality of plants you produced. Inappropriate budgeting like cost cutting specially on lighting would just prove to be uneconomical and inefficient in the long run.

A general rule for lighting that area coverage is determined by a light wattage output. Reflectors might be used to increase the light area and reach corners but effectiveness is still determined by this formula.

Day and Night Cycles

The type of plant and its stage of growth generally determine the amount of light needed. A common cycle is that with 18 hours of light and 6 hours of darkness which is recommended for its vegetative growth phase.

For seedlings, a continuous light source is needed until the first real leaves appear. When the leaves appear, the regular 18/6 light cycle is used. Fluorescent or incandescent lights are best for seedling because of the low heat and soft light they generate. Automated timers maybe used to ensure consistent light cycles. Inexpensive timers are also available; this can be found any hardware or Home Depot/ Lowe’s type store.

Light and Photosynthesis

The plants exposure to light intensity, duration and light color directly affects the amount of energy needed for photosynthesis. The color of the light, Blue simulates the summer sun, Orange for autumn seem to stimulate photosynthesis best. The light spectrum produced by metal halide bulbs (Blue lights) and high pressure sodium bulbs (red/ orange lights) produce this effects. HID grow lights produce these effects owing to their popularity to hobbyist and professionals. Combination of metal halide and high pressure sodium bulbs provides the complete spectrum of light produced by the sun.

Use Caution When Working with Lights

The combination of water, electricity and chemicals in such a closed-in space makes the grow room one of the most dangerous places in your house. Keep in mind to separate your ballast by elevating it from the water-containing areas of your hydroponic growing system.