Grow Lights

The biggest hurdle to growing plants indoor is having enough light. Using a grow light can remedy many issues with indoor gardening. It can give you the flexibility of growing anywhere in your home and not be reliant on sunlight coming through your windows.

Understanding the light that plants need

Light intensity is measured in lumens (lm) for most household lights. Lumens is a basic unit of measurement for light brightness as perceived by the human eye.

However, what may seem to be bright to our eyes may not appear as bright to plants. A light fixture that has more blue and red light would have lower lumens than a green and yellow light which our eyes are more sensitive to.

The light spectrum range useful for plant growth is defined as Photosynthetically Active Radiation (PAR) which refers to the wavelength from 400nm to 700nm. This is usually expressed as Photosynthetic Photon Flux Density (PPFD) value. Its unit in is µmol/m²/s, which measures the number of photons in the suitable spectra range received by the plant surface at a certain time. The larger the value, the more usable light by plants is reaching the plant surface. This value can be found in the specifications for various grow lights.

Choosing the right light for your environment and plant needs

There are many kinds of light you can use to grow plants indoors but the most common are LED household lights or grow lights. LED lights are generally preferred as they produce less heat. Plants can burn if they grow too close to or touch very hot bulbs!

LED household lights: for indoor ornamental plants

LED household lights contain red and blue wavelengths within the light spectrum, which are necessary for photosynthesis albeit at lower intensity. They look like indirect natural sunlight, and are enough for most ornamental indoor plants. These lights can be put on a timer to customise how many hours of light your indoor plants can get. These systems are relatively inexpensive and easy to put together.

LED grow lights: for plants that need more light

LED grow lights are specially modified to produce more light in the red and blue wavelengths which allows for better plant growth, with PPFD values high enough to be equivalent to direct sunlight. They are usually tailored to maximising the growth of edible plants grown indoors, with custom lights making it possible to grow cold weather crops in air conditioned rooms. These systems can get very expensive, but can also yield a variety of crops when used well.

For more information on grow lights and indoor gardening, download our Introduction to Indoor Gardening brochure!