Buy a full-spectrum white LED. Put it 15 to 60 cm (6 to 24 in) above the plant, and run it on a timer for 10 to 12 hours a day. That covers most houseplants.
The style of lamp matters less than those three things. A plain grow bulb in a desk lamp you own will keep a pothos happy all winter. Amazon carries full-spectrum LED grow bulbs that fit a standard lamp.
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Do you need a grow light?
A grow light helps when a plant has run out of window. These are the signs.
- Stems stretch toward the glass, with long gaps between leaves.
- New leaves come in small and pale.
- Pink, white, or purple leaves fade to green.
- Succulents lean and flatten.
- The soil stays wet for more than two weeks.
- The plant sits more than 2 m (6 ft) from a window, or the room has none.
In a northern winter, most homes have at least one plant that fits this list. Read winter houseplant care in a cold climate.
What to look for
| Feature | What to buy | Why |
|---|---|---|
| Type | LED | Runs cool, uses little power, and lasts for years |
| Color | Full-spectrum white | Plants grow well under it, and the room still looks normal |
| Color temperature | 4000K to 6500K | A neutral to cool white, close to daylight |
| Brightness | The brightest your space allows | A stronger light can sit higher and cover more plants |
| Timer | Built in, or a plug-in timer | Plants need the light every day |
| Mount | A way to raise and lower it | Distance is the main control you have |
Skip the purple lights. Red and blue “blurple” lamps grow plants, but they turn a living room into a nightclub and make it hard to see pests or yellow leaves. White LEDs do the job and look better.
Read the box with care. “Equal to 100 watts” tells you how bright the light looks to a person. It does not tell you how much light reaches a leaf. If the maker lists PPFD at a set distance, that is the useful number. It measures the light a plant can use at that spot. A maker who lists it is a maker who tested the lamp.
Pick a style for your space
| Style | Best for | Watch for |
|---|---|---|
| Grow bulb in a lamp you own | One or two plants on a desk or side table | Use a lamp that can aim down at the plant |
| Clip-on or gooseneck lamp | A windowsill, a shelf edge, or a single pot | Cheap clips sag. Check the clamp. |
| LED bar or strip | A plant shelf, one bar per shelf | Needs the shelf above to mount on |
| Hanging pendant | A floor plant or a group on a table | Needs a ceiling hook and a cord route |
| Floor lamp with a grow head | A tall plant in a dim corner | The head must reach above the plant |
| Panel on a stand | Succulents and seedlings | Bright and plain. Not living room decor. |
For a plant shelf, look at LED grow light bars on Amazon. For one pot, a clip-on grow light from Amazon is the simplest start.
A hanging pendant is the one that passes for a normal light fixture. The Sill carries Soltech hanging grow lights in its plant care collection.
How far from the plant
Light drops fast with distance. Moving a lamp from 30 cm to 60 cm (1 to 2 ft) away cuts the light on the leaf by more than half.
| Plant | Distance from a typical grow bulb |
|---|---|
| Low-light plants: ZZ plant, snake plant, pothos | 30 to 60 cm (1 to 2 ft) |
| Medium-light plants: calathea, ferns, peperomia, philodendron | 30 to 45 cm (12 to 18 in) |
| Bright-light plants: fiddle leaf fig, hoya, variegated plants | 15 to 30 cm (6 to 12 in) |
| Succulents and cacti | 15 to 20 cm (6 to 8 in), under a strong light |
Stronger lights sit farther back. Follow the maker’s distance if the box gives one.
Check your work with the plant. Bleached, pale, or crispy patches on the top leaves mean the lamp is too close. Stretching and leaning mean it is too far. Move it 10 cm (4 in) at a time and wait two weeks.
How many hours a day
| Use | Hours |
|---|---|
| A plant near a window that needs a boost | 4 to 6 hours, in the morning or evening |
| A plant with little or no daylight | 10 to 12 hours |
| Succulents and cacti with no sunny window | 12 to 14 hours |
Do not run a grow light around the clock. Plants need dark hours.
Put the light on a timer. This matters more than which lamp you buy. A plug-in outlet timer from Amazon is cheap and never forgets.
Care changes under a grow light
- Water more often. A plant that gets more light grows more and drinks more. Check the soil by touch.
- Feed if it is growing. A plant under a light for 12 hours a day keeps growing in winter. Feed it at half strength once a month.
- Turn the pot. A single lamp lights one side.
- Dust the leaves and the lamp. Dust blocks light at both ends.
- Keep the fixture dry. Do not mist near a bulb, and use a lamp rated for damp rooms in a bathroom.
Which plants gain the most
- Succulents, cacti, and string of pearls in a home with no south window.
- Pink and variegated plants, such as ‘Pink Princess’ philodendron and ‘Marble Queen’ pothos, that fade in winter.
- Fiddle leaf fig and bird of paradise in a room with small windows.
- African violets and moth orchids that will not bloom again.
- Any plant in a room with no window. Read houseplants that do not need sunlight.
What a grow light costs to run
LEDs use little power. To work out the cost, multiply the watts by the hours per day, divide by 1,000, and multiply by your power rate per kilowatt-hour.
A 20-watt bulb for 12 hours uses 0.24 kilowatt-hours a day. Look up the rate on your power bill and multiply.
Quick answers
Can I use a regular LED bulb as a grow light? A bright, cool white LED bulb placed close will keep low-light plants alive. A grow bulb gives more usable light for the same power.
Do grow lights work through winter? Yes. Winter is when they help most.
Can a grow light burn a plant? Yes, if it is too close. Pale or crispy patches on the top leaves are the sign.
Are grow lights safe to leave on when I am out? Use a timer, a fixture in good repair, and keep it clear of curtains and water.
Do grow lights replace a window? For low and medium-light plants, yes. Succulents need a strong light placed close.