Grow Lights

Grow Lights – Detailed Guide For Beginners

Q: Do I have to use grow lights?

A: No. Grow lights are not a necessity to keep succulents alive. Most people do not use them. For plant enthusiasts, however, they can greatly help keep your succulents healthy and looking their best.

Succulents come from climates that are sunnier than most parts of Canada. Here, we have good natural light for part of the year, but during the darker months the light is less than ideal. Succulent houseplants can have their colours fade and they can take on a “stretched” look, with their leaves opening and stretching to absorb as much light as possible. Grow lights can be an excellent solution for those that want to keep their plants at their best.

Both of these succulents are the same species. The one on the right is colourful and compact (grown in good light). The one on the left has been growing in less than ideal light: it’s faded to green and is stretching for light (this is called etiolation). Both are healthy, but the plant on the right clearly looks better (image from Succulent Studios).

Q: Alright, I’ve decided I’d like to get a grow light. Do I need to buy a special, fancy, or expensive grow light?

A: No. Regular light bulbs and fixtures can be used. They don’t need to be labelled “grow lights.” The key is to make sure they are bright enough and that they are placed close enough to the plants.

Basic Info On Light

In horticulture, light intensity is often measured in units called foot candles or lux. We will use lux in this guide (more on this later). Here are some examples:

Direct summer sun at noon: 120000 lux
Sun with light cloud cover: 30000-40000 lux
Bright outdoor shade: 10000 lux
Typical indoor lighting: 1000-5000 lux
Dim indoor lighting: 500 lux

You can measure light intensity anywhere using a lux meter (20-30$ on Amazon, any brand is fine), or a light meter phone app. In order for the apps to work accurately the front camera of your phone must be covered with a piece of paper to “diffuse” the light. The apps should have clear instructions.

Which Type of Grow Light?

Many light bulbs can be used as grow lights. Which kind depends on how large of an area you need to cover. LED lights are the best choice: they are energy efficient and don’t get too hot. For succulents, they generally need to be placed within 12 inches/30cm of the plants. Here are some examples:

When you purchase regular light bulbs, they will have a lumen rating on the box (general interior lighting uses this instead of lux). The higher lumens, the brighter the bulb. There is no answer to the question “what lumen bulb should I buy?” because the lumen rating can be listed on bulbs of many different sizes. For example, at 12 inches directly above the plants, 3000 lumens from a smaller bulb will give a higher intensity than under a larger 4ft 3000 lumen tube light, because the intensity is less spread out. The 4-foot tube light will cover a larger area, but at a lower intensity as the lumens are more spread out.

Light bulbs also have a kelvin colour temperature. This is a number that shows how warm or cool the light colour is (see below). Anything from 3000K – 5000K will work. I like 4000K bulbs; I find 3000k looks too yellow and 5000K looks too harsh/white for home use. Use whatever you prefer. Other grow lights are “burple,” or a mix of blue and red (the main parts of the light spectrum that plants use). These may not be as effective and give off a bright purple colour; not necessarily ideal for a home environment.

*“Burple” grow lights over succulents (Reddit)*

Grow lights can be ordered online or bought at a hardware store. If possible, it’s good to go to a store. You can look at the bulbs with the highest lumen ratings and hold your phone or lux meter close to the demo model to actually measure the light intensity – to really know what you’re getting.

Indoor Grow Light Guide

High light species: echeveria, sedum, graptopetalum, pachyphytum, crassula, cacti, aloe, agave, aeonium, kalanchoe, adromischus, cotelydon, lithops, conophytum.
Lower light species: haworthia, haworthiopsis, tulista, sansevieria, gasteria, zamioculcas, hoya.

Outcome	*High Light Succulents*	*Lower Light Succulents*
Inadequate	Less than 10000 lux	Less than 1000 lux
Helps, but prefers more	10000 – 15000 lux	2000 – 4000 lux
Not bad	15000 – 20000 lux	4000 – 7000 lux
Ideal for best growth / colour	20000 – 50000+ lux	7000 – 15000+ lux

General guide. Varies from species to species. Succulents can handle higher light ratings outside in natural outdoor conditions.

Once you get your grow lights, it’s time to set them up. This could mean placing them on shelves, in a lamp fixture, etc. Use your lux meter or phone app to measure the intensity: place it where the succulents will be and take note of the reading. Move the lights closer or further from the plants to match the guidelines above. Be sure to measure the entire area where the plants will sit, as the intensity can drop quickly away from the light. The picture here displays this idea; hypothetical readings show how light intensity can vary drastically with proximity to a grow light.

ESSENTIALLY: 1) Choose one or more bulbs that will cover your area 2) Choose the kelvin colour 3) Set them up 4) Measure the light and move them closer or further depending on the species.

Some people place their succulents and lights by a window. In this way the grow lights supplement natural light – helps greatly in winter and probably won’t be needed at all in the brighter months. Others grow their plants under lights with little or no natural light – this can work too. It is possible to grow completely healthy plants with only artificial light.

Grow lights should be on for 9 -12 hours a day for best results. A manual or wifi timer outlet works great to automatically turn the lights on and off at the same time each day.

Grow lights can look very BRIGHT, especially when it’s dark out. I live in a small apartment and have plants in my living room. The timer is set to come on at 7am (before I even get up) and turn off at 5pm, so they blend with natural daylight and aren’t on after nightfall. If you have a lot of grow lights you may need to put them in a separate room – it can get too bright!

If you have succulents that have been in lower light and you want to buy some grow lights, do not move the plants suddenly from low light to intense light. A sudden change from dim to intense light can cause damage/burning on succulents and cacti. Expose them gradually by placing the light further away at first, or cover the plants with a piece of old screen material to block some of the light as they adjust (window screen material blocks about 40% of light). Then after a week or two you can expose them to full intensity and they should be fine. After growing in bright light for a while, a stress response may occur in the succulent, bringing vivid colours.

Some grow lights may have info/terms such as PPF, PPFD, PAR, infared, UV, spectrum, etc. These are topics that are a little more advanced and more important to experienced or professional growers who are looking to maximize efficiency. There is no need to understand this info to get started. If you are keen, though, feel free to do further research.

Ultimately, using grow lights can keep your succulents in excellent health and is a good learning experience. There is no “one size fits all” approach to grow lights as everyone has different plants, goals, area to cover, natural light levels, etc. Observe how different plants react to different lighting levels. You can learn by taking light readings in different situations. In time you will learn and gain expertise. Understanding light is the most important topic in raising houseplants such as succulents. Gaining knowledge and experience can be rewarding and result in top-notch plants.

Grow Light Buying Guide

Q: Any tips for which brands to buy etc?
A: As noted above, lots and lots of bulbs can be used as grow lights. I don’t recommend any specific brand, although the brands I use are listed below. Look for bulbs that have good ratings, and are from a reputable manufacturer. Avoid the cheapest products online (especially Amazon), as there are a lot of junk LEDs on the market. They are generally weak and no good for more than a few plants. They also burn out faster or could even be a fire hazard. I recommend going to a store if possible to really see/measure how bright the lights are in person.

Q: What grow lights do you use?
A: I primarily use tube LED lights, from the following brands, placed about 3-6 inches above the plants:

Barrina 4ft T8 LED Shop Light, 5000K, 5000lm, 40W (Amazon)
Feit Electric 4 ft. 2-Light Integrated LED Shop Light, 4000K, 4500lm, 38W (Home Depot)

I prefer tube lights because they give even coverage and uniform intensity. I also sometimes use bright (at least 2000lm) standard shape LED bulbs (various brands), in a gooseneck lamp aimed at the plants (for smaller areas or to give a boost during wintertime).

I hope this info has been helpful. You can use it as a general guide to create your own setup. I do not provide specific recommendations for which grow light to buy for individual setups. Rather I provide this guide as a great starting point for my customers who are interested.