Lighting
How many hours of light does a plant need?
What is a grow light?
A plant needs light for photosynthesis, without light a plants leaves soon yellow and the plant will die. Indoors the plant does not have access to sunlight and needs this light source replacing. This is where grow lights come in. In short a grow light is a light used for growing plants. These normally come in the form of either a HPS (High Pressure Sodium) or MH (Metal Halide) bulb, a reflector and a ballast.
A ballast is the powerpack for your light, it ignites the bulb and regulates the power, making sure the energy needed is given. Ballasts are available in 250 watt, 400 watt, 600 watt and 1000 watts. The right ballast is needed to power the bulb i.e. a 400 watt ballast will only power a 400 watt bulb, not a 250 or 600 watt.
The reflector is used to maximise the usage of light, and ensures all light is reflected down onto plants and not onto the ceiling of your growroom. We will cover reflectors in more detail in another article.
The most important part of a growlight is arguably the bulb, normally in the shape of a HPS (High Pressure Sodium) bulb or MH (Metal Halide) bulb. HPS is the most popular as it gives out a red spectrum suitable for flowering plants, but many growers will use HPS all the way through their grow. MH is more specifically used for vegetative growth as it gives out more of a blue spectrum of light.
What are CFL's?
A CFL is a compact fluorescent lamp, also known as a compact fluorescent light or energy saving light. CFL's and other fluorescent lights work by passing electricity through gaseous vapour under low pressure.
They are most efficiently used as a light for young plants during the propagation stage, for seedlings and cuttings. CFL's perform well as a propagation light as they are cooling running, so they will not cause heat problems and also allow you to get your light closer to your plants to maximise usage.
You can also use CFL's as supplementary light in the flowering period of your plants. The more light you can get in a growroom, the better the plants will do. And CFL's are a great way of adding extras lumens without adding extra problems with heat.
Small scale growers may also find a use for CFL's as they are so cool running they can be used in small growrooms and even cupboard grows where it would be very hard to run a HPS or MH light without turning the cupboard into an oven.
How many hours of light does a plant need?
The hours of light a plant needs is called the photoperiod, it is the relationship between the duration of the light period and dark period. The photoperiod affects the life cycle and growth of all plants. Most plants in the vegetative period need 18 hours of light and 6 hours. Some growers do give young plants 24 hours of light for faster growth.
Plants can be 'triggered' to flower by changing the photoperiod to 12 hours of light and 12 hours of darkness. This will trick the plant into thinking it is the right time of year to flower.
The very basics of photoperiods are 18 hours of light for vegatative growth and 12 hours of light for flowering. This will suit most plants.