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HOW TO GIVE YOUR ORCHIDS THE RIGHT LIGHT

Learn about natural sunlight and artificial lights, including fluorescent and LED lights, to grow orchids.

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Several years ago I lived in an apartment with a large living room. An enormous tree grew right in front of the window, effectively blocking the window and making the room dark and dreary. The living room for all its spaciousness was not where I wanted to be. Like us, plants need light, and providing the right light for orchids is actually quite easy. 

The right light is essential for orchids to photosynthesis – the process plants use light to make food from carbon dioxide and water. The proper light makes flowering possible. In providing light to your orchids there are just 3 things you need to know about light: intensity, duration, and quality. 

Chances are if your orchid won’t bloom, it needs more light. Here’s what you need to know about light. Hint: you can do this!

Thank-You-now-I-know-just-where-to-put-my-orchid - Give Your Orchids the Right Light

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1- Light INTENSITY

Light intensity refers to the strength of the light. When thinking about light – think of Goldilocks, it has to be just right.

If the light isn’t strong enough, the orchid won’t produce enough energy to produce flowers. The overall vigor of the plant will be weak. Leaves will be thin and long. The plant will be leggy and straggly. 

On the other hand, too much light and the leaves will sunburn. Not only do sunburned leaves look ugly, but it also reduces the surface area on the leaves where the plant can photosynthesize. 

If the light intensity is just right – the orchid will be able to use light to convert carbon dioxide and water into energy. Leaves will be strong, light in color. The orchid will use its stored energy to produce flowers – just as nature intended.

To get the light intensity right there are a couple of things you can do:

  • Find the right location
  • Measure the light

Find the Right Location

First, if you are growing your orchid in a windowsill, an east-facing window is generally considered ideal. In climates with a lot of cloud cover, a full south exposure may be the right location. North-facing windows generally lack sufficient intensity, while west-facing windows can be too intense. The intense afternoon sun that shines through on west-facing windows can be minimized by hanging a thin, sheer curtain. 

Growing Orchids Indoors With Natural Light – Location Location Location

The goal is to give the orchid enough light that it can grow and flower without sunburning. While it may be tempting to place an orchid right up close to a window, that practice is not necessary, and may even be harmful to the orchid.  Placing your orchid a couple of feet away from the window, but not right in the middle of the room, is usually just the right light for orchids. 

Measure the Light

Second, you can measure the intensity of the light. There are 4 different ways to do this. 

  1. Light meter
  2. Light meter app
  3. Your hand and a piece of white paper
  4. The orchid’s foliage

Let me quickly talk about two measurements of light – foot candles and lux. Light for orchids is traditionally measured in foot candles. A foot-candle (fc) is the amount of light one candle emits from one foot away. So, if the orchid requires 1500 foot candles that means that it would take 1500 candles 1 foot away from the orchid to get enough light.

You can also measure light intensity in lux, the basic unit of illuminance, the metric system unit of light measurement. Online there are numerous calculators that will convert lux to fc and fc to lux. Or, you can do the conversion yourself.

Light Meter

The most accurate way to measure light is to use a light meter. You can buy an expensive light meter, use a camera, or you can download an app on your phone. 

Light Meter App

The apps can be free, or low cost.

Hand Method

Another method, that’s not as accurate, but is still helpful and doesn’t require anything except your hand, is the hand method. To use the hand method, hold your hand 8-10” away from a white piece of paper in the area where you want to measure the intensity of the light. See the table to see how to “read” the hand method.

Foliage 

Generally, the leaf color of orchids should be light green, not dark green. In addition, elongated, stretching orchids need more light. 

3 Ways to Measure Light Intensity

Light Intensity

Foot-Candle

Lux

Hand-Paper

Intense

4000 - 5000

43056 - 53819

Clear outline of hand

Very Bright

3000 - 4000

32291 - 43056

Soft-edged outline of hand

Bright

2000 - 3000

21528 - 32291

Blurred outline of hand

Low

1000 - 2000

10764 - 21528

Hard to see outline of hand

Light Intensity by Genus

Genus

Foot Candles

Lux

Brassia

2000 - 3000

21528 - 32292

Cattleya

2000 - 4000

21528 - 43055

Dendrobium

1500 - 5000

16146 - 53819

Paphiopedilum

1000 - 2000

10764 - 21528

Phalaenopsis

1000 - 1500

10764 - 16146

Vanda

4500-5000

48437 - 53819

2-Light DURATION – Photoperiod

Light intensity refers to the strength of the light and duration measures the length of the day or the photoperiod. 

The day length changes with the seasons. The closer you are to the equator, the more consistent the day length, and the further you are from the equator, the more the season affects light duration. In Alaska, the days are long in the summer and short in the winter. In Central America, there’s day length remains the same year-round. 

What this means for us is that we need to place our orchids in a location where they will receive a consistent day and night schedule. 

If you use artificial lights, timers are invaluable. It might be tempting to leave the lights on all the time, thinking that the more light you get, the more they will grow. This isn’t true. Orchids need night, just like they need a day. Timers lend consistency. If you use a timer, you don’t have to remember to turn the lights on in the morning and off at night. You can go on vacation. Timers automate light duration for you. I love timers!

3- Light – QUALITY

So far, we’ve discussed the strength of the light (intensity), and the photoperiod (light duration). Now, let’s talk about light quality, or the amount of red, far-red, green, and blue light coming from the light source. 

If you grow your orchids outdoors or in a greenhouse your orchids will naturally get the full-spectrum of light needed to grow. If you grow your orchids on the windowsill, or under lights, light quality becomes an important factor. Some windows block ultraviolet light. And, not all artificial light emits the correct distribution of the light wavelengths needed. Both fluorescent and LED light can provide the full spectrum of light needed to successfully grow orchids.

Growing Orchids Indoors with Artificial Light

I started out growing all my orchids on a window sill, but as my collection began to expand, I needed more space. That’s when I high-jacked the grow light system I had given to my husband.

Before going into depth on growing orchids under lights, I want to give a shout out to horticulturist, Steve Frowine. I’ve learned a lot about growing orchids under lights from him. He has grown orchids for over 50 years and is the author of several books on growing orchids.

If you aren’t sure about using artificial light to grow orchids, here’s 6 reasons to give lights a try:

  1. For windowsill growers, in the summer it can get very hot and the light can become too intense when the sun pours in. By growing orchids under lights, the light intensity is easier to regulate. 
  2. After introducing artificial lights I was able to grow more orchid varieties. My miniature Cattleyas and Dendrobiums flourish under lights. 
  3. Grow light system facilitates blooming. I was thrilled when my Cattleya bloomed using the grow light system.
  4. I had a lot more space to grow my orchids than I did before. I set up the grow light system on a counter and the orchids do well, blooming, putting out new roots, and leaves.
  5. Fluorescent bulbs are cheap and readily available.
  6. LED grow lights are becoming less expensive and easier to come by.

Fluorescent Lights

3 Things to Look for When Buying Fluorescent Bulbs

  1. The Color Rendering Index (CRI) should be a minimum of 85, but preferably in the 90s. (The higher the number the better).
  2. Color Temperature (Kelvin), shoot for bulbs between 5000-6500 K.
  3. Lumen Output. This is a method for measuring light brightness. The higher the number, the more efficient the bulb is. Choose a bulb with the highest lumen per watt.

LED Lights

Recently, I’ve added LED lights to my orchid growing menagerie. Here’s the scoop on LED (light-emitting diode) lights: 

As plants require a distribution of blue, green, red, and far-red light, it is recommended that you choose a full-spectrum LED light bulb. By purchasing an LED light that is specially designed for indoor plants you’ll be buying a light that provides the full spectrum of light for your orchids. LED lights designed for hydroponics will suit your orchids.

Use A Timer

As mentioned earlier, using a light timer makes artificial lighting even easier.  Leave the lights on between 12-16 hours a day. Never leave the lights on for 24 hours a day. Orchids do need a rest at night.

Why Artificial Lights Work

  1. Orchids need certain a certain quality of light – particular colors in the light spectrum to bloom and grow – and full-spectrum fluorescent bulbs and LED lights can provide those colors.
  2. Fluorescent bulbs and LED lights can provide evenly distributed light, which helps prevent sunburning the orchids.

TIP:   Compact orchids do much better under lights than do tall orchids as the intensity of the light diminishes the further the orchid is from the bulb. The Cattleyas and Dendrobiums I grow under lights are miniature varieties. Place the bulb 6 to 12 inches above the orchid’s leaves.  

Which Orchids Grow Best Under Lights?

For best results, grow orchids with low to medium light requirements under lights such as the Phalaenopsis and Paphiopedilum and compact orchids, those under 12 inches. 

TIP: The light intensity is strongest in the center of the fluorescent tube. Set your Cattleya in the middle and your Phalaenopsis on the ends of the tube.

Tips to Give Orchids More Light

In addition to placing your orchid in the right location and providing artificial light when needed, there are a couple more things you can do to give light to your orchids.

  • MIRRORS – you can double the amount of light by placing mirrors opposite a window or light bulb. Adjust the angle of the mirror so that you don’t burn the orchid, but instead illuminate a former shadow.
  • ROTATING PLANT TOWARDS LIGHT SOURCE – Orchids, like all plants grow towards the light. This is especially important if the orchid’s light source is a window and the light comes in from one direction. I have found that by rotating a phalaenopsis orchid, I can get the flower stalk to grow more upright.

orchids-artificial-lighting - give your orchids the right light

How to Tell if Orchids Have the Right Light

There are two good indicators that will tell you if your orchids are getting sufficient light.

  1. Flowers. Blooming takes a lot of energy, which comes from getting enough light. If you have enough energy to bloom normally (right season, right color), it is getting enough light.
  2. Leaves. The leaves should be light green in color, and generally, the leaves should be upright, short, and firm. Some orchids such as Cymbidiums and Oncidiums do have long thin, arching leaves.

How to Tell if Orchids Have Too Much Light

  1. Sunburn. Just like us, orchids can sunburn, resulting in a large black spot with a yellow ring around it. If leaves are hot to the touch, they are too warm.
  2. Yellow leaves. Orchid leaves should be bright green. Yellowish leaves can indicate too much light.

Here is a peek into my basement where I grow my orchids. This is the grow light system I use. To the far right, you can see a bit of the humidifier I use. (The humidifier I use is no longer available, but here is a link to another humidifier.) To the left of the humidifier you can see the humidistat I use to track humidity and temperature. Out of sight on the left, there is a fan to keep the air moving and a timer for the lights. Under these lights, I grow Cattleya and Dendrobium orchids. The Dendrobium in the very center is growing some flower spikes. It’s hard to see in this image, but one of the Dendrobiums in the back has several keikis (offsets) that have started to grow.

Give Your Orchids the Right Light

Here is a peek into my basement where I grow my orchids. This is the grow light system I use. To the far right, you can see a bit of the humidifier I use. (The humidifier I use is no longer available, but here is a link to another humidifier.) To the left of the humidifier you can see the humidistat I use to track humidity and temperature. Out of sight on the left, there is a fan to keep the air moving and a timer for the lights. Under these lights, I grow Cattleya and Dendrobium orchids. The Dendrobium in the very center is growing some flower spikes. It’s hard to see in this image, but one of the Dendrobiums in the back has several keikis (offsets) that have started to grow.LED lights - grow orchids

Your Turn

Giving light to your orchids will help your orchids give back to you by flowering. Although I have discussed both growing orchids at a windowsill and under lights, don’t feel like you have to use lights to grow orchids.

If your windowsill is providing your orchids with the light they need, then keep using this method. If, on the other hand, your orchids aren’t blooming like they should, setting up a simple grow light system may be the solution you are looking for.

Once your orchid flowers have opened up, you can bring them out from under lights and into the living area of your house so that you can enjoy the flowers. Just be careful not to bring them out too soon. Not long ago I had a Phalaenopsis that was loaded with buds. I was anxious to see the flowers open and brought the orchid to my kitchen table. I lost a few buds to bud blast. 

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11 Comments
  1. Kathi-Ann says:

    Anna, I am really having a hard time getting my Dendrobiums to rebloom. I have repotted them to allow the roots to get more air and placed them in bright light. I also used some sphagnum moss to help with moisture. I really need help here. It’s becoming frustrating. I live in the tropics so it s hot here.

    1. Anna says:

      Kathi Ann,
      As Dendrobiums don’t like to be re-potted, it may take them a while to recover and bloom. I know it’s hard, but give them time. Dendrobiums do like bright, indirect light. It sounds like you have that covered.

      Do you happen to know which species of Dendrobiums you are growing? There are three basic types: warm, intermediate and cool growing. And they can be either deciduous or evergreen. For your tropical climate, the warm-growing evergreen species should do well. Some popular species include: Phalaenanthes, Spatulata and Latouria.
      I hope this helps!
      Anna

  2. Chris Nault says:

    I have a big aquarium, made out of rattan, could I use that and an aquarium light? So, floating around, I have a 10 gal., a 20 gal. the rattan one is 50 gal. All have hoods and lights.

    1. Anna says:

      Chris,
      Your rattan aquarium sounds beautiful. To turn your aquarium into a terrarium, be sure to grow orchids that grow well in terrarium conditions – high humidity and low air circulation. I found a link that sells orchids specifically geared toward terrariums:

      Seattle Orchid

      On the end of your aquarium light, you should see tiny print with the bulbs specifications. Compare it to the fluorescent light specifications provided on this page. Also, if you do decide to purchase an orchid from Seattle Orchid, you could ask them about your light and recommending a suitable orchid for your growing conditions.
      Best,
      Anna

  3. Ellie Stell says:

    Very informative

  4. Glenda Toon says:

    Hi Anna,
    My moth orchard is down to 2 flowers and these are fading fast. I thought it was ready to have a rest but have just noticed a new leaf forming.
    Do I feed it or do I cut down the watering?
    I’m confused.
    Cheers
    Glenda

    1. Anna says:

      Glenda,
      Yes, do cut the flower spike. You don’t need to cut down on the water or fertilizer as we are headed into summer and your orchid is still in active growth.
      All my best,
      Anna

  5. Sherri says:

    HI Anna,
    We live in Colorado and we don’t keep our heat very high in our home plus we have radiant floor heat which is even cooler. Im trying to think of a way to keep my orchids healthier and growing in winter months. My thought was maybe lights. Any ideas? Ive tried the bathroom and actually most rooms in my home. Thanks. Sherri

    1. Anna says:

      Sherri,
      We are neighbors – I live in Utah.
      The easiest thing to do would be to choose orchids that like cool temperatures. Phalaenopsis orchids like a month with temperatures down to 55-60 F / 13-16 C. There are also many Dendrobium orchids that enjoy cool winters (just not dens in sections bigibbum and phalaenanthe – they are warm growers and are sensitive to temperature drops).
      A couple of things that I do to keep my warm-growing orchids happy throughout the winter is to use seed mats. Fluorescent lights will add a bit of warmth – more than LEDs. My humidifier also has a “warm” button. Every little bit helps, but none of these options create a lot of heat.
      All my best,
      Anna

  6. Patrick Sr McConnell says:

    Hi my name is Patrick. I have been growing three varieties of orchids for the past three years. I have 24 cattleyas, 24 Phal, and 14 Vandas. I grow the cattleyas and Phals in a east window during summer then move them under t5 ho lights for winter. I have no problem blooming the phals but the cattleyas are a bit harder. I use agrobrite full spectrum on both but get to much heat. I have up graded to a led setup for my Vandas. You say you have used led a floresent for cattleyas. Who to you recommend for growing my cattleyas under LED. The Cri and PPf is much better with led. I’ve looked at Active grow replacement t5 for my 8 bulb agrobrite lamp but even with using t5 led bulbs at 24 watts that’s still almost 300 watts. There is spider farmer and Mars led and ledwarehouse has some great lights at that wattage that you don’t have to run 16-18 hours a day. Please any help you can give me before I make a purchase would be greatly appreciated. Thank you Patrick

    1. Anna says:

      Patrick,
      Your orchid collection sounds amazing! I recommend using 4-8 broad-spectrum lamps. If looking for a specific brand, I recommend GRO-Lux. If you like to check them out, here is an amazon affiliate link:
      Gro-Lux Wide spectrum Fluorescent Lights
      All my best,
      Anna

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