Your houseplants looked perfectly happy by the window all summer. But now that winter is approaching, something seems different.
Your pothos is growing more slowly. Your monstera's new leaves are smaller than usual. That beautiful plant in the corner hasn't produced a new leaf in weeks.
You haven't changed how you care for them. So what's happening?
The answer may be simpler than you think: your plants aren't getting the same amount of light they received during summer.
As daylight hours shorten and the sun's position changes, the amount of light reaching your indoor plants can change significantly.
But how much light do houseplants actually need in winter? And when should you consider using a grow light?
Let's find out.
1. Why Do Houseplants Get Less Light in Winter?
Even if your plants haven't moved, their lighting conditions may have changed.
Three seasonal factors can make a difference.
Shorter Daylight Hours
During winter, the days become shorter across much of North America.
In many northern locations, plants may receive several fewer hours of natural daylight compared with summer.
With fewer daylight hours available, plants have less time to capture the light energy needed for photosynthesis.
More Cloudy Days
In some regions, winter brings extended periods of cloudy or overcast weather.
Even when daylight is available, clouds can reduce the intensity of sunlight reaching your windows.
A spot that once provided bright natural light may now offer much dimmer conditions.
Changing Sun Angles
The sun follows a lower path across the sky during winter.
Interestingly, this doesn't mean every window receives less direct sunlight.
In the Northern Hemisphere, south-facing windows may receive more direct sunlight at certain times of day during winter because of the lower sun angle.
However, shorter days, surrounding buildings, window placement, and shading still affect how much useful light reaches your plants.
The key takeaway: Don't assume your plants receive the same light year-round just because they stay in the same location.
2. How Can You Tell If Your Houseplants Aren't Getting Enough Light?
Plants can't tell you when they're struggling with low light, but they often show visible signs.
Here are five common symptoms to watch for.
1. Long, Weak Stems
When plants receive insufficient light, some species begin stretching toward the available light source.
The spaces between leaves become longer, and the plant may develop a thin, leggy appearance.
This is commonly called etiolation.
2. Smaller New Leaves
Have you noticed your monstera or philodendron producing smaller leaves than before?
Insufficient light can limit the energy available for new growth.
However, leaf size also depends on plant maturity, nutrition, and growing conditions.
3. Slower or Stopped Growth
Many houseplants naturally grow more slowly during winter.
But if a plant receives much less light than it needs, its growth may slow significantly or stop.
This doesn't always mean the plant is unhealthy. It may simply be responding to seasonal conditions.
4. Yellowing or Dropping Leaves
Some plants shed older leaves when they cannot maintain all their foliage under reduced light.
However, yellow leaves can also result from overwatering, nutrient issues, or root problems.
Always check other growing conditions before assuming low light is the cause.
5. Leaning Toward the Window
If your plant is noticeably leaning or growing toward a window, it may be responding to directional light.
Some movement toward a light source is normal.
But pronounced stretching, especially alongside smaller leaves and weak growth, may indicate insufficient lighting.
Remember: One symptom alone doesn't confirm a lighting problem. Look for several signs and consider the plant's overall condition.
3. How Much Light Do Different Houseplants Need?
Not every houseplant needs the same amount of light.
Some plants naturally grow beneath dense forest canopies, while others originate from open, sunny environments.
Understanding these differences is more useful than following a single lighting rule.
Low-Light-Tolerant Plants
Examples include:
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Snake Plant
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ZZ Plant
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Cast Iron Plant
These plants generally tolerate lower indoor light levels than many other houseplants.
However, low-light tolerant doesn't mean no-light required.
Even shade-tolerant plants need enough light to maintain their health over time.
Medium-Light Plants
Examples include:
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Pothos
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Heartleaf Philodendron
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Aglaonema
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Peace Lily
Many common foliage plants perform well in medium to bright indirect light.
During winter, they may benefit from being moved closer to a suitable window.
Bright-Light Plants
Examples include:
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Monstera
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Fiddle Leaf Fig
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Many Hoya species
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Many Succulents and Cacti
These plants generally need brighter conditions to maintain healthy growth.
Some prefer bright indirect light, while many succulents and cacti tolerate or require several hours of direct sunlight.
Their exact requirements vary by species.
The important question isn't simply how many hours of light your plant receives. It's how much usable light reaches its leaves throughout the day.
4. Light Intensity vs. Light Duration: What's the Difference?
When people talk about plant lighting, they often focus on the number of hours a light stays on.
But light duration is only part of the story.
Two important factors determine how much light energy a plant receives.
Light Intensity
Light intensity describes how much light reaches the plant at a given moment.
For plant lighting, intensity is commonly expressed as PPFD (Photosynthetic Photon Flux Density), measured in µmol/m²/s.
A plant close to a suitable grow light may receive significantly more usable light than one sitting several feet away.
Distance, light coverage, and fixture design all matter.
Light Duration
Light duration describes how long the plant receives light during a 24-hour period.
Together, intensity and duration determine the total amount of photosynthetically active light reaching the plant each day.
This total is known as the Daily Light Integral (DLI).
For example, a plant receiving moderate light for 12 hours may receive more total daily light than one exposed to very weak light for 16 hours.
That's why leaving a dim light on longer isn't always enough to compensate for poor light intensity.
5. How Many Hours Should Grow Lights Be On in Winter?
For many common foliage houseplants, 12–14 hours of artificial lighting per day is a reasonable starting point when using grow lights as a primary or substantial light source.
However, this isn't a universal requirement.
The ideal schedule depends on the plant's light needs, the intensity of the grow light, and how much natural daylight the plant already receives.
If your plant receives several hours of useful natural light through a window, supplemental lighting may help fill the gap.
If it grows in a dark room with little natural daylight, the grow light may need to provide most of its daily light.
For many indoor plants, total lighting periods of roughly 12–16 hours are commonly used, but providing more hours isn't automatically better.
Plants also need darkness.
Most houseplants benefit from a consistent day-and-night cycle, and continuous 24-hour lighting is not recommended.
Some flowering plants, including poinsettias and Christmas cacti, have specific dark-period requirements that influence flowering.
A simple timer can help maintain a consistent lighting schedule without requiring you to remember when to turn the lights on and off.
6. Can You Give Houseplants Too Much Light in Winter?
Yes.
Although insufficient light is common during winter, excessive light can also damage plants.
Signs of too much light may include:
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Pale or bleached leaves
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Brown, scorched patches
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Crispy areas exposed directly to the light
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Leaf stress after sudden changes in lighting
Moving a plant from a dim location directly under a powerful grow light may expose it to more light than it can comfortably tolerate.
Start with moderate lighting and increase gradually.
Monitor the leaves and new growth, and adjust the light's intensity or distance if necessary.
7. How to Give Your Houseplants More Light During Winter
Before purchasing a grow light, look at ways to improve the natural light your plants already receive.
Move Plants Closer to Windows
Light levels can drop considerably as you move farther from a window.
A plant several feet away may receive much less light than one positioned close to the glass.
Moving it closer can make a meaningful difference.
Just avoid placing cold-sensitive plants against freezing window glass or in drafty locations.
Make Better Use of Available Daylight
Keep windows clean and open curtains or blinds during daylight hours.
Observe where sunlight actually falls throughout the day, rather than assuming a room is bright enough because it looks comfortable to you.
Avoid Crowding Plants
When large leaves overlap or taller plants shade smaller ones, not every leaf receives the same amount of light.
Rearranging plants can improve light distribution.
Add Supplemental Grow Lighting
If natural daylight is insufficient, an LED grow light can help provide additional photosynthetically useful light.
Full-spectrum white grow lights are a practical choice for many foliage houseplants, especially when you want lighting that also looks natural in your living space.
A suitable grow light can be particularly useful for:
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Apartments with limited natural daylight
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North-facing rooms
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Plant shelves away from windows
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Indoor plants during long periods of cloudy weather
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Plants with relatively high light requirements
Remember that a grow light's effectiveness depends on its output, coverage area, positioning, and operating schedule—not simply its wattage.
8. How to Position a Grow Light Correctly
One of the most common grow light mistakes is placing the fixture too far from the plant.
Light intensity generally decreases as distance increases, although the exact relationship depends on the fixture's optical design.
A light that appears bright to your eyes may deliver insufficient light to the leaves if positioned too far away.
Start with the distance and coverage guidance provided by the grow light manufacturer.
Then consider these factors:
Plant Height: Position the light so it illuminates the leaves effectively without placing them too close to the fixture.
Coverage Area: A single grow light may not provide uniform lighting across a large group of plants.
Light Intensity: Use the fixture's PPFD information, when available, to understand the light reaching the plant at different distances.
Plant Response: Watch for healthy new growth, unusual stretching, or signs of excessive light.
Consistency: Maintain a regular lighting schedule rather than frequently changing settings.
The best setup is one that matches your plant's needs and is easy to maintain throughout the season.
9. Should You Use Grow Lights All Winter?
Not necessarily.
Some plants receive enough natural light even during winter, especially when placed near bright, unobstructed windows.
Others may benefit from supplemental lighting throughout the shorter days.
And some plants naturally enter a period of reduced growth, making additional lighting less important than maintaining stable temperatures and appropriate watering.
Consider supplemental lighting when:
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Your plant shows consistent signs of insufficient light.
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Available daylight falls below the plant's needs.
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You want to maintain active growth during winter.
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You are growing plants in locations with little usable natural light.
The goal isn't to force every plant to grow rapidly throughout winter.
It's to provide suitable conditions for the plant you have.
Frequently Asked Questions
Q: Is sunlight through a window enough for houseplants in winter?
For some plants, yes. Bright windows can provide sufficient light, especially for species with modest lighting requirements. Others may need additional lighting depending on location and seasonal conditions.
Q: Can I leave my grow lights on 24 hours a day?
No. Most houseplants benefit from a regular dark period. A consistent lighting schedule is generally more appropriate than continuous illumination.
Q: Do LED grow lights work for indoor plants?
Yes. Suitable LED grow lights can provide the wavelengths and intensity needed for photosynthesis. Their effectiveness depends on the fixture and how it is used.
Q: How do I know if my grow light is too far away?
Check the manufacturer's recommended distance and PPFD measurements. Slow growth, stretching, or weak development may indicate insufficient light, although other factors can contribute.
Q: Should I increase watering when using a grow light?
Possibly. If supplemental lighting encourages more active growth, your plant may use more water. Always check the potting mix rather than automatically increasing watering frequency.
The Bottom Line: Give Your Plants the Light They Need
Winter doesn't have to mean struggling houseplants.
For many indoor plants, a few thoughtful adjustments can make a meaningful difference.
Pay attention to changing daylight, learn the signs of insufficient light, and consider supplemental grow lighting when natural light isn't enough.
Most importantly, remember that healthy plant care isn't about providing the maximum amount of light. It's about providing the right amount of light.
With the right balance of intensity, duration, and consistency, you can help your indoor plants stay healthy through the darker months.
Part of the GLOWRIUM Fall & Winter Houseplant Care Guide.
Keep Growing, All Winter.
