If you are growing anything indoors — seedlings, herbs, microgreens, or houseplants — you will eventually need to understand grow lights. Even a bright south-facing window falls short during the short days of winter, and many indoor growing spaces have no direct sunlight at all. The right grow light transforms any shelf, counter, or closet into a productive growing space year-round.
The grow light market can feel overwhelming. LED panels, T5 fluorescent tubes, compact fluorescents, full spectrum, red and blue, PAR values, PPFD ratings — the jargon piles up fast. This guide cuts through the confusion and gives you practical, straightforward advice on choosing the right light for your indoor garden based on what you are actually growing.
Understanding Light for Plants: PAR and PPFD Explained Simply
Plants do not care about lumens or lux — those measurements describe how bright light appears to human eyes. Plants care about photosynthetically active radiation, or PAR, which is the range of light wavelengths between 400 and 700 nanometres that drive photosynthesis.
PPFD stands for photosynthetic photon flux density. It measures the number of photosynthetically active photons hitting a given area per second, expressed in micromoles per square metre per second. In practical terms, PPFD tells you how much usable light is actually reaching your plants.
Here is what you need to know without the technical deep dive. Low-light plants like lettuce and herbs do well at 100 to 200 PPFD. Seedlings thrive at 200 to 400 PPFD. Fruiting plants like tomatoes and peppers need 400 to 800 PPFD or more. Microgreens, which are only growing for one to two weeks, do fine at 100 to 200 PPFD.
When comparing grow lights, PPFD at a given distance is far more useful than wattage alone. A well-designed 100-watt LED can deliver more usable light than a 200-watt fluorescent because it converts more electricity into the wavelengths plants actually use. Always check the PPFD rating at the distance you plan to hang the light, not just the wattage.
LED Grow Lights: The Modern Standard
LED grow lights have become the default choice for indoor growers, and for good reason. They are energy efficient, produce relatively little heat, last for years, and are available in a wide range of sizes and price points. Modern LEDs produce full-spectrum white light that works well for all growth stages, eliminating the need for the purple-pink blurple lights that dominated the market a few years ago.
There are several categories of LED grow lights to understand. Entry-level LED panels in the twenty to fifty dollar range are perfectly adequate for herbs, microgreens, and seedlings. These typically draw fifteen to thirty watts and cover a one to two square foot area effectively. Mid-range LED panels costing fifty to one hundred fifty dollars draw fifty to one hundred fifty watts and cover two to four square feet — suitable for a small herb garden or seed-starting shelf. High-output LED fixtures above one hundred fifty dollars are designed for serious indoor growing, including fruiting plants, but are overkill for most kitchen gardening.
For most indoor food growing — herbs on a counter, microgreens on a shelf, seedlings before transplanting outdoors — an entry-level or mid-range LED panel is all you need. Look for full-spectrum white LEDs with a colour temperature of 4000K to 6500K. These produce a natural-looking white light that is pleasant in living spaces, unlike the harsh purple of older models.
A practical and often overlooked option is a standard LED shop light. A four-foot LED shop light from any hardware store costs fifteen to twenty-five dollars, draws about forty watts, and produces enough light for a full shelf of seedlings or microgreens. It will not have the optimised spectrum of a dedicated grow light, but for leafy greens and seedlings, the difference is minimal. Many experienced growers use shop lights exclusively and get excellent results.
T5 Fluorescent Grow Lights
T5 fluorescent tubes were the gold standard for indoor growing before LEDs took over, and they remain a solid option. T5 refers to the tube diameter — five-eighths of an inch — and these slim tubes produce a broad, even spread of light that is well-suited to seedlings and leafy greens.
A standard four-foot, four-tube T5 fixture costs forty to sixty dollars and draws about one hundred twenty watts. It covers roughly a two-by-four-foot area effectively. The light output is good — comparable to a mid-range LED panel — but the electricity cost is higher and the bulbs need replacing every twelve to eighteen months as they lose output.
The main advantage of T5 fluorescents is even light distribution. The long tubes spread light uniformly across a wide area, which is ideal for trays of seedlings or microgreens where you want consistent growth edge to edge. LEDs, especially point-source panels, can create hot spots in the centre and dimmer edges.
The disadvantages are meaningful, though. T5 fixtures are bulkier than LED panels. They produce more heat, which matters in small spaces. Replacement bulbs cost ten to fifteen dollars each and need swapping regularly. And they use roughly twice the electricity of an equivalent LED to produce similar light output. For a small setup — one or two trays — the electricity difference is negligible. For a larger shelf garden running twelve hours a day year-round, the energy savings of LED add up significantly.
If you already own a T5 fixture, there is no urgent reason to replace it. It will grow excellent herbs, seedlings, and microgreens. But if you are buying new, LED is the better investment for most people.
CFL Grow Lights
Compact fluorescent lights — the spiral bulbs that screw into standard light sockets — are the simplest and cheapest entry point for indoor growing. A 23-watt CFL bulb costs three to five dollars and produces enough light for a single potted herb or a small group of seedlings. You can use any desk lamp or clip-on light fixture you already own.
CFLs produce a broad spectrum of light and are available in daylight colour temperatures (5000K to 6500K) that work well for growing. The biggest limitation is coverage area. A single CFL only lights a circle about eight to twelve inches in diameter effectively. For a single herb pot on a desk, that is fine. For a tray of microgreens or a row of seedling pots, you need multiple bulbs.
CFLs are also less energy efficient than LEDs and produce more heat relative to their light output. They are best thought of as a temporary or supplemental solution rather than a primary grow light for a serious indoor garden. If you want to test whether a particular herb will survive on your kitchen counter before investing in a proper setup, a five-dollar CFL in a clip lamp is a reasonable experiment.
Wattage Per Square Foot: A Practical Guide
The amount of light your plants need depends on what you are growing. Here are practical wattage guidelines for LED lights, which are the most efficient option. If you are using fluorescents, roughly double these numbers to get equivalent light output.
For microgreens and sprouts, aim for fifteen to twenty-five watts of LED per square foot. These crops grow fast and do not need intense light. For herbs and leafy greens, twenty to thirty watts per square foot keeps plants compact and productive. For seedlings that will be transplanted outdoors, twenty to thirty watts per square foot prevents the leggy, stretched growth that comes from insufficient light. For fruiting plants like indoor tomatoes or peppers, you need forty to sixty watts per square foot, which is why most casual indoor growers stick to leafy greens and herbs.
Calculate the area you want to light and multiply by the appropriate wattage. A two-by-four-foot shelf for seedlings needs roughly one hundred sixty to two hundred forty watts of LED light. A one-by-two-foot countertop herb garden needs about forty to sixty watts. A single ten-by-twenty-inch microgreen tray needs roughly twenty to thirty watts.
Height, Distance, and Positioning
How far above your plants you mount the light affects both intensity and coverage area. Closer means more intense light over a smaller area. Further means less intense light spread over a wider area. The relationship follows the inverse square law — doubling the distance reduces intensity to one quarter.
For seedlings and microgreens under LED panels, start with the light four to six inches above the tops of the plants. If you see the seedlings stretching toward the light, move it closer. If the leaf tips curl or show light burn — yellowing or bleaching — raise it up. With T5 fluorescents, two to four inches is typical because they produce less concentrated light.
As plants grow, you need to adjust the light height to maintain the right distance. Adjustable hanging chains or ratchet hangers make this easy. Some shelf gardens use fixed lights and rely on raising or lowering the plant trays instead.
For uniform coverage, centre the light over your growing area. If you are using a rectangular LED panel over a rectangular tray, align them to match. If you notice plants at the edges leaning toward the centre, your light is not covering the full area — either add a second light or use a wider fixture.
Timer Setup and Light Schedules
Consistency matters more than duration for most indoor growing. Plants use their dark period for important metabolic processes, so running lights twenty-four hours a day is counterproductive for most crops. Set your lights on a timer and forget about them.
For seedlings, twelve to sixteen hours of light per day is optimal. Fourteen hours is a good default. For herbs, twelve to fourteen hours keeps most varieties productive without stressing them. For microgreens, ten to twelve hours is sufficient — they are only under the light for a few days before harvest. For seed starting indoors, sixteen hours of light followed by eight hours of dark promotes strong, compact growth.
A basic mechanical timer costs five to ten dollars and is one of the best investments you can make for indoor growing. Plug your light into the timer, set the on and off times, and your plants get consistent light every day without you having to remember. Digital timers with multiple on/off cycles cost a few dollars more and are useful if you want to split the light period — for example, eight hours on, four off, six hours on, six off — though a single continuous period is simplest.
Electricity Cost: What Indoor Lighting Actually Costs to Run
Electricity cost is a common concern for new indoor growers, but the numbers are smaller than most people expect. To calculate your cost, multiply the wattage of your light by the hours per day it runs, divide by 1000 to get kilowatt-hours, and multiply by your electricity rate.
A 30-watt LED panel running fourteen hours a day uses 0.42 kilowatt-hours per day. At the US average electricity rate of roughly fifteen cents per kilowatt-hour, that costs about six cents per day, or roughly two dollars per month. A 100-watt LED panel running fourteen hours per day costs about twenty cents per day, or six dollars per month. A 120-watt T5 fluorescent fixture running the same schedule costs about twenty-five cents per day, or seven fifty per month.
For a small herb garden or microgreen station, the electricity cost is genuinely negligible — less than a dollar or two per month with LED lighting. Even a larger seed-starting setup with multiple lights adds only five to ten dollars per month to your electricity bill during the growing season. The savings from growing your own seedlings, herbs, and microgreens far outweigh the power cost.
Best Light Types by Application
To summarise the practical recommendations: for a small countertop herb garden with one to three pots, a single CFL or a small LED panel is sufficient and costs under twenty dollars. For a microgreen growing station with one to two trays, an LED shop light or entry-level LED panel in the twenty to forty dollar range is ideal. For a seed-starting shelf with multiple trays, a four-foot LED shop light or a dedicated LED panel in the forty to eighty dollar range covers a full shelf. For a larger indoor garden with herbs, greens, and seedlings, invest in a proper LED grow light panel that matches your shelf dimensions.
Whatever light you choose, remember that consistency, proper distance, and a timer are more important than having the most expensive fixture. Plants respond to steady, predictable light cycles. A twenty-dollar LED shop light on a timer, hung at the right height, will outperform a hundred-dollar panel that gets moved around and run inconsistently. For more guidance on sourcing quality equipment, browse our materials and buying guides.
Frequently Asked Questions
Can I use regular household LED bulbs as grow lights?
Yes, standard household LED bulbs in the 5000K to 6500K daylight range will grow herbs, microgreens, and seedlings. They are not optimised for plant growth — they emit more green and yellow light than plants need and less red and blue — but they absolutely work for leafy greens and seedlings. A 15-watt daylight LED bulb in a desk lamp is enough for a single herb pot. For larger areas, dedicated grow lights are more efficient, but household bulbs are a perfectly acceptable starting point.
How do I know if my plants are getting enough light?
The most reliable indicator is plant behaviour. Stems that stretch and become tall and thin — called etiolation — are reaching for more light. Leaves that are small, pale, or spaced far apart on the stem indicate insufficient light. Herbs that grow slowly and produce weak flavour are likely light-starved. Conversely, leaf tips that curl, yellow, or bleach are getting too much light or the light is too close. Compact, bushy growth with rich green colour and strong flavour indicates your lighting is in the right range.
Do plants need different light colours for different growth stages?
The old advice about blue light for vegetative growth and red light for flowering has been oversimplified. Plants use the full visible spectrum, and modern full-spectrum white LEDs provide everything most indoor food crops need. If you are growing herbs, greens, microgreens, or starting seedlings, a full-spectrum white light with a colour temperature of 4000K to 6500K is all you need. Specialised red and blue spectrums are more relevant for commercial cannabis and flower production than for kitchen gardening.
How long do LED grow lights last?
Quality LED grow lights are rated for 50,000 hours or more, which translates to roughly ten years of use at fourteen hours per day. LEDs do lose output gradually over time — a process called lumen depreciation — but the decline is slow. After 25,000 hours, most LEDs still produce 90 percent or more of their original output. Compare this to T5 fluorescent tubes, which need replacing every 10,000 to 15,000 hours, and the long-term value of LEDs is clear.
Is it worth buying expensive full-spectrum grow lights or will cheap ones work?
For herbs, microgreens, and seedlings, inexpensive LED lights work very well. The difference between a twenty-dollar LED shop light and a hundred-dollar specialised grow panel is primarily in efficiency, spectrum optimisation, and build quality — not in whether your basil will grow. Expensive lights matter more for high-light crops like tomatoes and peppers where maximising PPFD per watt is important. For most indoor kitchen gardening, spend your budget on good seeds and growing medium rather than premium lighting.