Indoor gardening lets you grow everything from houseplants to fresh herbs and vegetables regardless of season or outdoor conditions. Grow lights make this possible by providing the light energy plants need to photosynthesise. This guide covers what to know to get started, from choosing a light to giving your plants the right amount of it.
Why use grow lights?
Sunlight contains the full spectrum of light plants use to photosynthesise, and grow lights replicate it indoors. That lets plants grow where natural light is limited, such as apartments, basements, or places with short winter days.
NASA has used LED grow lights in controlled environments such as the Veggie and Advanced Plant Habitat systems on the International Space Station, tailoring the light spectrum to the needs of the plants.
What to consider when setting up grow lights
Choosing the right colour temperature
Colour temperature is measured in Kelvin (K). Lower values look warm and reddish, and higher values look cool and bluish. Plants respond to the red and blue wavelengths in the light, as explained in what type of light do plants need to grow:
Red-rich light encourages flowering and fruiting.
Blue-rich light supports leafy, vegetative growth with strong stems.
For general indoor gardening, a full-spectrum grow light that looks like natural light supports all stages of growth, which makes it versatile for houseplants, herbs and vegetables.
Positioning the grow light
The distance between plants and light decides how much light they receive. If the light is too far away, plants become leggy as they stretch toward it. If it is too close, they can overheat or be damaged. As a rule of thumb (it depends on the light's intensity):
Seedlings: about 15 to 30cm from the tops of the seedlings.
Houseplants: typically 30 to 60cm.
Vegetables and herbs: 15 to 30cm, depending on the light's intensity.
An adjustable light is a great investment because you can raise it as plants grow. Learn more in how much light do plants need.
Photoperiod: how long to leave the light on
The time your light is on each day is called the photoperiod. Plants fall into three groups:
Short-day plants need less than 12 hours of light a day (for example chrysanthemums and poinsettias).
Long-day plants need 14 to 18 hours (for example vegetable seedlings and garden flowers).
Day-neutral plants are happy with 8 to 12 hours regardless of season (for example African violets and geraniums).
Pro tip: for most indoor plants a 12 to 16 hour photoperiod works well. A smart plug or timer automates it.
Setting up grow lights for different plants
Seedlings
Seedlings are sensitive to light and need plenty of energy to grow into strong plants. Use a full-spectrum light and position it close, about 15 to 30cm away.
Photoperiod: 14 to 16 hours a day. Avoid continuous light, because plants need darkness for respiration and other essential processes.
Tip: pale or leggy seedlings are probably not getting enough light, so move them closer.
Houseplants
Houseplants vary widely. Shade-tolerant plants such as snake plants and pothos need minimal light, while orchids and succulents need more intense, full-spectrum light.
Distance: most houseplants do well with a light 30 to 60cm away.
Photoperiod: depending on the species, 8 to 14 hours a day.
Herbs, vegetables and fruit
Edible plants often need more intense light and a longer photoperiod to match outdoor sun.
Light type: leafy greens do well under full-spectrum light. Fruiting plants such as tomatoes and chillies benefit from plenty of light and some red wavelengths to support flowering and fruiting.
Distance: 15 to 30cm from herbs and vegetables.
Photoperiod: leafy greens need about 10 to 12 hours, while sun-loving herbs and fruiting plants may need up to 18 hours.
The benefits of LED grow lights
LED grow lights are the most popular choice for indoor gardening because they are energy efficient and long lasting. Compared with traditional fluorescent or incandescent bulbs, LEDs typically use much less energy and last far longer. See LED grow lights compared with other horticultural lights.
Cost savings: lower energy use can reduce your electricity bill over time.
Customisable spectrums: many LED lights let you adjust the spectrum or brightness to suit your plants.
Controls: LEDs can be switched on and off rapidly and are easy to dim. With fluorescent or halogen lights, frequent switching can shorten their life.
Final tips
Monitor your plants. Check regularly for pale leaves or slow growth and adjust the distance as needed.
Use a timer. It gives plants consistent light without manual switching.
Choose the right light. Full-spectrum lights suit most indoor gardens, though some fruiting and flowering plants benefit from extra red.
With the right setup, grow lights can turn any indoor space into a thriving garden. Browse our LED grow lights to find the right one.
What we would use
The Sun Bulb has an adjustable beam from 15 to 50 degrees, and Sun Bulb mounts hold it in place.
