From not enough light, to too much – this post is intended to help you understand and find the “Goldilocks Zone” of ideal light for your Phalaneopsis. Light is the single most important aspect of plant care next to water because providing enough of it ensures the plant has the energy to grow quickly and bloom with more flowers. Phalaenopsis which do not get enough light can exist for YEARS in your home and grow slowly, never blooming, and not really doing anything—in extremely low light they will eventually die (which can take many weeks to many months to happen). It’s better for you to understand the concept of light, otherwise you could run into a myriad of problems thinking they’re related to your orchid’s potting media, or fertilizer, or humidity…when really, your plant just wasn’t getting enough light.
Before we get into the tell tale signs of too much vs. too little light, I’ve included a graphic below which helps visualize the correlation of leaf color with light intensity—please understand that the exact color values are not A RULE—it’s a guideline intended to help you broadly understand the concept that leaf colors of a plant change based on the intensity of light. All plants are like this – when light is low, they get more chlorophyll and become dark green. In extreme cases of low light the plant and leaves will stretch, a condition called etiolation. Conversely, in too much light, plants can become pale or yellow. Phals, like other plants, respond to light as well and although they need less light compared to trees, cacti or succulents…they still need considerably more than you may think; and often more than what you will find in your home (unless you have many large windows – in which case, lucky you). Individual types (species/hybrids) of phalaenopsis will naturally have leaf color variation – some deep forest green while others have pale mint colored leaves; however, all phal’s leaves will change as the intensity of light is higher or lower. Some may even get red spots, while others develop white patterns which is called leaf “mottling”
THE POINT? If your plant’s leaves are at the extremes of the chart, consider corrective action. Here’s the chart…
1. Signs a Phalaenopsis is Not Getting Enough Light
- Your phal grows slowly, only putting out a new root or two at a time.
- Your orchid either doesn’t bloom or if it does it only has a few flowers.
- The leaves are long and skinny OR short and stumpy compared to the previous leaves that grew before you got the plant.
- Finally (and this one’s harder to tell because it will depend on the species/hybrid you have), the leaves are very dark green (refer to graphic above). Also note: if you’re feeding too much phosphorus, your plant can also develop very dark green leaves unrelated to light levels…which is one reason why this whole post a “generalization” and not a black and white rule book.
Natural Light, Windows & Light Dispersion
Know this: the walls and roof around your windows block nearly 100% of sunlight—light cannot pass through wood or concrete. In nature, in the forest, light does pass through leaves and is reflected off a million different surfaces as the wind blows. In your home, a plant to the left, right or below a window may not be get enough light even though the room feels bright to your eyes. Be analytical and observe how light is dispersed in your home at different times of the day. Test putting plants in different places in your home and see where you get the best growth. Using plant cuttings from pothos and other common tropical plants is a great way to test and assess how one plant performs in different places.
See the two graphics below, showing how light entering home can create sharp shadows and clear zones of no light. You can use a sheer curtain to disperse light and help mitigate “dead zones” in your room
Window Direction & Season: East and West windows will allow for light to penetrate deep into your home as the angle of the sun changes from sunrise to sun set. South windows will create a distinct tracking across your home from the West to the East as the sun travels from East to West; in the winter (when the sun is lower in the sky), light will also penetrate deeper into your home, however, the daylight hours will be shorter. You can disperse light by using sheer curtains, but really your objective for the best growth is to provide direct *but filtered* light…putting your orchid directly in front of the window, but filtering it to reduce intensity with a sheer curtain is an ideal solution.
Examples of Orchids Grown Behind Sheer Curtain
Photo and orchids grown by F. Henderson in Edmonton Canada.
2. Signs a Phalaenopsis is Getting Too Much Light
- You’re getting leaf burn—once a leaf is burnt, it’s irreversible.
*If you’re moving your orchid near a window, you should do so slowly over the period of a week or two. Putting an orchid that has been growing in dark conditions into a very bright window can sometimes burn the plant more easily than if you had moved it slowly.
- The leaves are pale-chartreuse or yellowish rather than green is a sign of too much light. Plants grown under too much light are generally stressed and won’t grow as quickly, their leaves will be shorter, thicker, and hard. The upper limit of phal leaf colour is about the same as a granny smith apple, but there are many species that have dark-green leaves that will never get this bright green color. Those darker plants under bright light can either burn or start to develop spots or banding when grown in ideal light.
- The leaves are turning red or purple. If you push the light past ideal on a plant that has red/purple flowers, it often means it has a lot of red pigment. That will sometimes show up in the leaf. If you see red or purple fringing on your leaves, it doesn’t necessarily mean that you should to switch to lower light; however, darker leaves will absorb heat faster, so be sure to check the leaf temp with your hand–if it feels warm to the touch, get your plant to a lower-light area before you risk burning the leaf.
A note about high light and nutrient issues: There is a relationship with high light and nutrient-related issues. When plants are “over clocked” and grown at the upper limit of their preferred range of light, they will need more nutrients to support faster growth. Light == energy, right? But, in order for a plant to convert that light-energy into usable building blocks for growth, it also needs Calcium, Magnesium, Nitrogen, Phosphorus, etc etc etc. You may notice chlorosis, reddening of the leaves, or other leaf stresses which can be signs of nutrient deficiencies which are expressed in higher light situations. In some cases you can remedy this (and get your plant to grow fast and large) by providing either more nutrients or by refining micro nutrients or optimizing nutrient availability via pH management. This is where botany and horticulture get a bit more technical, but just understand if you’re “over clocking” your plants you can remedy some issues simply by providing more nutrients. However, be very careful about recognizing the difference between nutrient-related stress from high light intensity compared to heat-related stress as a result of leaf temperature.
3. Just the Right Amount of Light
- How do you know if your phal is happy? To start, it should always be growing! This is especially true in the spring, summer and fall; sometimes during the winter as daylight periods are reduced, your plant will stall. If it’s the growing season outside, your phalaenopsis inside should be in the process of growing either new leaves, new roots, or a flower spike. The only time I’ve experienced a lag in growth is immediately following the buds opening into flowers–sometimes they’ll open and not grow for a couple of weeks as they replenish the energy from blooming process.
- Leaves are vibrant and full looking, not dull.
- Light freckling, speckling, silvering, or colour-flushing (red or purple). It will depend on the parent lineage of the orchid you have, but in most cases adequate light is right around the level where your plant starts to “blush” in the sun; generally phals that don’t blush, will turn a vibrant green-apple colour.
Finding the Goldilocks Light Zone for your Orchids
Using these points, keep a close eye on your plant and use observation to determine if your growing area has enough light. Move single plants around and experiment with different areas of your home – you might be surprised to find that the brightest area isn’t too bright to grow a beautiful phalaenopsis.
If you’re growing indoors and relying on natural light, your best bet is to use filtered sunlight behind a sheer curtain. That will give you bright sun…but not so much it will burn the leaves. Also, when moving plants from low light to high light, acclimate them slowly because in some cases a plant that was grown in dark conditions will have dark green leaves. Then when you move them to higher light, the leaves absorb more heat and can cook. So baby steps when moving from low light to more light
Alternatively, consider getting LED grow lights which pump out light and will give your plants continuous bright light throughout the day. It’s a topic I’ve covered in another post, but artificial light is a fantastic way to give your plants more light in place where they aren’t getting enough natural light.