Who’d be so dumb to have a ‘pot’ plant growing on their windowsill in their first, and only, year at law school? Me, of course.
Thirty years ago, it was a criminal offense, and I could have been locked-up. What’s worse, I only had a joint now and then, and the whole pot-plant thing was to impress the other students.
Now you’re thinking what’s this got to do with the growth of plants?
My flashback was sparked by my research on indoor plant growth and choosing the best grow light. A lot of the reading material on grow lamps use cannabis as their baseline plant. The fact that a well-known Nasa scientist’s lecture, on the effects of artificial light on cannabis, viewed over 600k times, might also be the reason for my ‘mary-jane’ slanted approach.
For marijuana growers, apart from the quality and different strains they cultivate, the bottom line is usually high-volume yields and higher income. How do they get it right more often than not? They use high-pressure sodium (HPS) grow lights in conjunction with metal halide (MH) lights. But more of this potent combination in the next section.
Similar useful plants like mint, tomatoes, chocolate, flax, and many more flourish well under HPS grow lights. My favorite is hemp, which has a fraction of the psychoactive substance found in marijuana and used to make paper, rope, biofuel, and more. Plants, like the liverwort, lower cholesterol and relieve stomach cramps, or hops the stabilizing agent in beer, and give it its bitter taste and fruity-floral aroma, thrive under HPS grow lamps. The point I’m making is that HPS lamps are used across the whole spectrum of the plant world, and not just to grow dope.
Let’s compare the different grow lights you can buy.
Plasma and LED grow lights are all the rage, but the former is very expensive if this is your first foray into grow lights, give it a wide berth. LEDs are more of an option if you plan on following the herd of fashionistas, but from what I can see, they’re not as practical and remarkable as they look.
Believe it or not, but LEDs can burn your plants if you’re not careful, an accusation that’s often leveled at HPS bulbs. Also, the inconsistent growth results between LED’s with the same wattage but from different manufacturers is enough reason to be nervous about buying one. Then there are the maintenance headaches you get because the chance of some or other glitch in the hi-tech panel could mean doing some specialized DIY. Or you could send it back to your supplier and leave your plants in the dark.
An HPS light gives you the results you expect, and if it blows, get yourself another one and be back on track in minutes.
When it comes to producing bumper volumes, HPS lamps beat LED’s hands down, especially in cold climates. LED’s cannot beat the yields you get with HPS lights. They’re catching up fast, but they still have some way to go before the pros outweigh the cons. The less expensive HPS lights ensure that your plants get their natural sunlight, even in winter so you can continue with your harvesting objectives uninterrupted.
Other grow lights on the market are fluorescents, the regular screw in ones you use at home, also known as CFLs, and T5’s which consist of fluorescents together in a panel. All these are great because they don’t consume much power, but if you continue using them during the flowering stage, you’ll have less yield. So what’s the use of saving money on energy when your yield is small. These grow lights don’t penetrate deep enough, and you could end up with short, stunted crops. An HPS light is powerful enough to boost height and triple your yield in comparison to other lamps.
Lastly, HPS lights are your go-to-option if you don’t have time to wait for the delayed and possibly unpredictable results of grow lamps other than HPS ones.
Before you buy your new light, and seeds and soil, and all the rest, there are a few things you should know to help you choose the best HPS grow light.
How To Choose The Best HPS Grow Lamp
An HPS light is part of the high-intensity discharge (HID) group of plant grow lights. If where you’ve planted gets cold, or if you want to give the final, flowering-cycle a massive boost, HPS grow lights are your best option. There are many growers, even in temperate climates, that rely on HPS lights for exceptional yields because they’ve stood the test of time.
Before looking at HPS lights more closely, there are a few factors to keep in mind to help you decide if this is what you want. You’ll also understand why and how combining HPS and metal halide (MH) grow lights is the smartest way to grow.
If all you want to use is an HPS light, it’s a good idea also to give your plants a dose of natural light. Sun gives the blue/green spectrum light, which boosts plant growth in the early stages. HPS lights don’t have enough of this spectrum of light. It would also be easier to track the health of your plants during these ‘natural’ sessions, which is hard to do in the bright yellow glare of HPS lights.
If you don’t have the means to let in natural light, if you’re growing in your basement, you should combine HPS and MH for the best results. These two lamps, working together, produce a bumper crop at the lowest cost.
You’d use an MH lamp at the beginning of a plant’s life-cycle, in its early-growth phase. The emitted light falls in the blue/green spectrum, like sunlight. This makes the plant believe there’s plenty of time to develop and grow. So they put all their energy into high-growth and become resilient to diseases, grow dense and compact foliage, and develop strong roots. At the peak of this cycle, you give your plants their needed dose of HPS light. An HPS lamp fools the plant into believing that summer’s almost over. The plant goes into overdrive to produce ‘fruit’ – flowers, seed, all the factors that complete its summer cycle – as fast as possible to ensure its survival. You’re actually ‘bluffing’ the plant.
If you believe plants have a soul, this isn’t for you! You’ll feel like you’re manipulating nature, which is actually the case. But, to soften your guilt, perhaps your plants want to grow up fast and are manipulating you as teenagers can do?
Most of the grow light units you’ll see in the next section are HPS and MH compatible, which is why I’ve explained this combination in such detail.
The crucial feature is the grow light you choose. Double-ended lights are more delicate and need care when you fit them. The regular one-ended screw-in types are much easier to handle. Expert growers, with big operations, prefer double-ended lights due to the balanced, denser, and more cost-effective light they emit. Either way, the light should match the power output the ballast provides. You get two types of bulbs, so be sure if you get a magnetic ballast, the globe’s compatible. A digital ballast can fire up both types of bulbs, whereas a magnetic one cannot.
A good ballast is one that:
- Has a safety mechanism to prevent the lamp from popping in a power surge
- Can switch between the two types of bulbs
- Can keep the temperature down
- Has a variable wattage selector
- Has a radio frequency shield
- Low noise emission
The hood and reflector is something else to consider. There are three types:
- Wings are simple reflectors above the bulb, and they’re your cheapest option. They don’t have a cooling system and tend to cause hot spots on plants.
- Air-cooled reflectors are attached to an exhaust duct that removes the excess heat from the growing area. They’re powerful and concentrate light efficiently onto plants.
- Cool tubes are where a bulb fits into a glass tube, and it is connected to an exhaust system that extracts the heat. The reflectors are generally small and don’t focus the light as well as an air-cooled one. That’s why they’re great for small areas.
- Umbrella reflectors are very effective for a larger area, but unfortunately, there aren’t any on the top ten list.
When it comes to wattage the range we’re focussed on is 250 watts to 1000 watts. Anything more and you’d be cultivating the turf on a football field. Here’s an idea of the power you’ll most likely need:
- 3 to 6 plants in 4 ft2 – 250W
- 6 to 10 plants in 10 ft2 use – 400W
- 11 to 14 plants in 16 ft2 use – 600W
- 15 to 20 plants in 30 ft2 use – 1000W
There you have it, the globe, the ballast, the hood, and the wattage explained in a way even I can understand.
The last and probably most crucial thing to know is the light. It sounds technical, but it isn’t. If I can understand it, you can.
Sellers often refer to the number of lumens a lamp emits, but lumens shouldn’t be your only metric. Instead, you should ask what the real factors are that affect plant growth. It could make a big difference to your energy bill, plant health, and growth, and yield volumes.
- How efficient the grow light unit is at converting electrical energy into photons? PPF (Joule per second)
- How dense are the photons that strike the plant? PPFD
- How much photosynthetic active radiation can your unit produce per second? PAR
I’ll go into this in more detail in the FAQ part of the article, but for now, this information should be enough.
There’s much to learn about grow lights, but if you’re a small scale grower, or just starting, this should be enough to help you choose the best HPS grow light.
Top 10 Best Hps Grow Lights
The Eye Horilux is the only grow light where the important metric PPFD is given and compels me to make this my number one choice. The PPFD range is 400 to 700nm, and you can alternate between a ceramic HPS, a daylight blue MH, and a super HPS grow light. It has an input voltage of 120 to 240V, and the wattage is 600W. If there’s too much heat, the ballast can be removed and operated from a distance of 15 feet.
The reflector is designed explicitly for the 600-watt lamp creating a uniform and consistent light distribution and focusses 20% more light on your plants. This unit is more effective than even the larger 1000W lights. If during your growing season, the reflector gets damaged, it can be replaced without having to buy a complete system. This 17 lbs unit is UL listed and is also the second priciest one on the list. A good buy due to its durability, innovative design with all the requirements for maximum yields included.
If you take a look at the Eye Horilux’s site, you’ll understand why I’m so impressed.
- Ballast can be separated from the unit for cooler operation
- Takes ceramic and regular HPS and MH bulbs
- Reflector design gives wide illumination
- Replaceable reflector
- A 3-year warranty
The HPS and MH lamps give the full-color spectrum for plant growth. A dimmable digital ballast and enhanced cooling fan reduce the heat by 25%, adding to its durability. The power range you get is from 150W to 400W. Safety features include overheating, short-circuit, end-of-bulb-life, and ignition failure protection.
It operates on a 120 and 240V power supply, and the 8-foot, 120V power cord is included.
The hi-tech aluminum reflector has a polished interior that boosts reflectivity by 20% and ensures that the light gets reflected evenly across your plants. It has a pair of adjustable heavy-duty rope hangers capable of holding up 150 lbs. The 20.9 lbs unit has an ETL listing that ensures it’s a high standard. For what you get in terms of power range, it does seem a bit pricey.
- High-reflective VEGA aluminum hood
- HPS and MH compatible
- Top-class safety features
- Mechanical timer switch
- Housing materials quite flimsy
- Noisy ballast
The Hongville grow light has a digital ballast that gives you the option to dim the light from full down to half power and is compatible with both HPS and MH globes. Its output ranges from 250 to 1000 Watts, and it has a voltage rating of 125V. High yields are a formality with the 400W super HPS bulb, which generates 30% more lumens.
The reflector’s interior is aluminum to enhance light reflection and reduce its weight. It also has a 24-hour dual-outlet timer spaced at 15-minute intervals. The flip-down glass makes the reflector easy to open and close, and there are rubber seals and steel clamp-locks for an air-tight close. An effective air cooling 6-inch duct allows air to pass through both ends of the reflector to ensure less heat build-up for maximum inline air cooling to protect your plants from excessive heat. It comes with an adjustable rope hanger that can hold over 150 lbs. This 23.7 lbs unit is one of the best-priced ones and has all you need except for an exhaust duct.
- HPS and MH compatible
The Yescom has a very streamlined design that cools air quickly, reducing heat and helps avoid plant damage. It’s HPS and MH compatible and has an output ranging from 250W to 1000W.
There’s a 6-inch exhaust that fits on an exhaust system of the same width on the one end to draw out the excess heat. The cool tempered glass tube and hood reflectors give it a 95% wide arc of light distribution.
It has a UL listed socket for compatibility with most bulbs
There are hooks you attach while assembling the unit, but no ropes are supplied, to hang the 6.7 lbs unit, nor is the bulb supplied. A very low-cost way to get into this enjoyable hobby
- HPS and MH compatible
- Less likely to cause hot spots on plants
- Spreads light very effectively
- All the wattage options
- Not easy to assemble
- Gets very hot
The iPower grow light unit is HPS and MH compatible, and the wattage for both is 600W.
The 600W digital dimmable electronic ballast can support a 120 to 240V input.
They can be dimmed from 50% up to 100%, and the stable power gives off the flicker-free, ultra-bright, high intensity, and top spectrum light. Included are 600W super HPS 2100K-lumen for the red and orange spectrum, and MH 6000K-lumen bulbs with excellent blue and violet spectrum as well as a high PAR rating.
The easy to mount heavy-duty has a light galvanized steel bracket.
The 19-inch aluminum-coated wing reflector lights up an area as wide as 16 sqft. There’s a UL listed, built-in 15-foot heavy duty lamp cord and a pair of 8-ft ropes with an adjustable ratchet that can hold up to 150 lbs. The 11 lbs unit comes with a 1-year warranty and is a bargain buy for a beginner grower.
- Separate ballast reduces hanging weight
- HPS and MH compatible
- Consistent light flow features
- Wing reflector edges sharp and dangerous
- Illumination not focused
The Mixjoy 1000W double-ended grow light unit powers a 2100K super lumens HPS bulb that has a PAR rating of 2100um+ and provides 35% more energy than a standard HPS lamp and emits more IR and UV light. The red and orange spectrum is optimized in the bulb to stimulate flowering. It’s a dual output of 120-240V and comes with an 8-foot power cord. The high-quality lamp holder is specifically designed for the double-ended lamp.
The high-frequency dimmable ballast has an adjustable output from 600W to 1150W. The sturdy reflective aluminum hood has 95% reflectivity. Altogether it weighs 19.1 lbs and is held up by an 8-foot adjustable ratchet clip hanger rope. The unit is ETL certified to ensure the ballast’s 3-year warranty and the globe’s 1-year warranty. This one’s quite pricey considering you cannot use an MH bulb, and unless my plants had access to natural light, I’d think twice before I bought it.
- High light spectrum and PAR rating
- Double-ended grow lamp
- A 3-year warranty
- High wattage
- Only takes an HPS light
- Pricey and heavy
The iPower Cool Tube is system has the full range of light your plant needs. The light deeply penetrates the cells and promotes healthy chlorophyll production as well as helps regulate the plant’s life-cycle.
The digital ballast has dimmable options from full down to half illumination. It has a voltage output of 120 to 240 Volts and is suitable for both HPS and MH lamps. The with a wattage range is from 250 up to 1000 Watts. The ballast switches between HPS and MH using microchip programming. It only takes a maximum of two minutes to ignite the lamp, and once it’s on full power, the electronic ballast helps it produce a third more lumens than a magnetic one would.
Its high-frequency output reduces power loss, and the acoustic resonance is nil.
The 6-inch air duct ensures maximum inline air cooling, and it has a built-in cooling fan and graduating fin to help keep the ballast cool. An internal resin coat adds to its durability. It’s wired with a standard hydroponic S-plug and includes a heavy-duty power cord. The stable voltage eliminates flickering and protects it from short-circuits, power surges, ignition failure, and overheating. Includes is a 24-hour plug-in timer with 15-minute interval options. It has an 8-foot heavy-duty adjustable clip hanger rope. This 18 lbs unit has CE certification, is UL listed, and has a 12-month warranty. Apart from an extractor duct, you’re getting most of what you need for a reasonable price.
- HPS and MH compatible
- Exhaust fit capability
- Switching ballast
- Quick ignition
- Ballast can interfere with other device’s frequencies
The Phantom Reflector compact unit has a digital ballast that operates 1000-Watt HPS or MH double-ended lamps at 600W, 750W, 1000W, and 1150W of power. It has an 8-foot power cord with a dual output of 120 and 240V. The improvised airflow characteristics help it run 20% cooler than other digital ballasts. The non-magnetic ballast is 30% more efficient compared to magnetic ones and it can be preset from 600 to 1150W.
It has an open style phantom reflector with hooks and ropes with an adjustable light ratchet hanger to enable you to easily hang the 4.61 lbs unit. The MH bulb is not included and it has a 1-year warranty. The priciest unit on the list and possibly won’t suit growers with tight budgets unless they’re growing a highly lucrative crop that’s been legalized.
- HPS and MH compatible
- Double-ended globe
- Switching ballast
- Illumination diffused and not focused enough
The Hydroplanet is a highly efficient and low energy consuming grow light. It uses a 150W HPS light and runs off an 8-foot, 120V power cord. It has a steel housing with vents to help dissipate the heat. Inlaid in the housing is a hammered aluminum insert for greater uniformity, output, and light diffusion.
There is a back-lit on and off switch on the housing, which also holds the magnetic ballast.
No assembly is needed for the unit, but a rope with an adjustable ratchet to hold the 10.35 lbs unit isn’t included. It has a 2-years warranty. This low-cost unit is suitable for the smaller grower or beginner.
- Low heat emission
- Excellent in cold climates
- Low energy consumption
- Magnetic ballast which doesn’t dim or switch
- Emits a buzzing sound
- Only takes an HPS light
The Hydro Crunch double ended pro series grow light system runs at in 1000W with a digital ballast operating the lamp at 600 through to 1150 Watts of power which you can preset. It has a dual input voltage of 120, and an included 240-volts adaptor and an 8-foot power cord. The airflow is good enough to keep the ballast running at 20% cooler than many similar ones. This non-magnetic ballast saves up to 30% compared to magnetic ones.
It has a closed reflector hood which has attachable hooks and includes a rope that holds up to 150 lbs, and adjustable light ratchet hanger. This 17.85 lbs unit system is already assembled, so installation should be quick and easy. It is an ETL, UL, and CE certified grow light system. The double-ended DE HPS bulb has a 1-year warranty and the unit as a whole a 2-year warranty. The price is in the midrange region, and although not the best bargain, it’s not a bad buy for what it does.
- The lamp has a 1-year warranty
- Double-ended glow lights
- No exhaust needed
- No hanging ropes and ratchet
- Only takes HPS lights
Ideally, who should use HPS grow lights?
- Growers living in cooler climates love them. The heat from HPS lights counteracts the low temperatures.
- If you’re growing more than five plants, you’re good to go with an HPS grow light.
- Growers using HPS lights should have at least six feet of vertical space for plants to grow. Don’t forget to add the height of the light to your calculations if this is you.
Are there two different types of ballast?
Yes, there are mechanical and digital ballasts. An electronic ballast produces a couple of hundred more Hertz than a mechanical one, but the main difference is that the former generates much less heat, and keeps your cooling costs down. It also uses much less electricity. A ballast cranks the voltage higher than the voltage supplied by the power grid.
Why does wattage seem to matter so much?
It affects the amount of illumination you give your plants and the cost of power. Experienced growers mostly use 600 watts because they’re cost-effective in all spheres of plant grow lights. They produce close to 10% more light (lumen-per-watt) than a 1000W HPS grow light. Keep in mind that Watts is the power input, whereas, with growth lights, we’re more focused on output or light spectrum. It’s where the magic happens.
Here’s a table to give you an idea of how to figure out your power requirements as well as the height you should set your grow light at:
- 150 watts, 8 inches high for a 4 sqft area
- 250 watts, 10 inches high for a 7 sqft area
- 400 watts, 14 inches high for a 12 sqft area
- 600 watts, 18 inches high for 16 sqft area
- 1000 watts, 23 inches high for a 25 sqft area
A grow light too close to your plants burns them, and too far can be just as bad but is also a waste of energy, time, and money.
Why is heat, cooling, and ventilation management so important with HPS lights?
The heat that these powerful lights generate affects your plants unless you take adequate precautions. If there’s a window or vent in the grow area, it would be wise to use it for ventilation. It would save you the cost of extraction fans and air ducts. Plants need a balanced environment, not only perfect light. The other factors, such as moisture, temperature, nutrients, and water flux, are just as crucial.
Too much heat and the plants could dehydrate. Some research on how you can maintain the balance is critical for a bountiful yield. A mechanical power plug with an auto-timer to set the operating time makes your life easier. The extras such as rails and a motor that moves the light to wherever you want it to go is another smart option. Some growers connect three grow lights to one motor to keep costs down.
What is the light spectrum, lumens, and PAR?
Lumens are the measurement of light intensity based on the human eye, the brightness of the light. With plants, the focus is more on photosynthetically active radiation (PAR). Natural sunlight is the golden standard of the light spectrum. Most suppliers of grow lamps aspire to emulate sunlight as much as possible and should be able to tell you the following:
- Photon Efficacy – refers to how efficient a grow light is at converting electrical energy into PAR.
- PPF – is the measurement of the total amount of active photosynthetic radiation (PAR) that’s produced by the light per second.
- PAR – the wavelength of light that drives photosynthesis; the spectral light quality that a plant needs for photosynthesis to occur.
- PPFD – the density of photosynthetic flux, the amount of PAR that falls on the plant, or spot reading on the plant. By taking the average reading of several measurements, at a defined height, you’ll know the density and how it diminishes as you move away from the center.
What else is there to know about High-Pressure and Metal Halide bulbs?
HPS lamps have double the lifespan, usually two years, depending on their quality than MH ones. Their spectrum of light output is six times more than standard incandescent grow lights. Because they efficiently supplement sunlight, they’re the preferred choice for growers with greenhouses.
Together, HPS and MH grow lights create growing conditions like a greenhouse, but in your basement.
Having an indoor garden seems rather daunting if you’ve never done it before, but once you start, it grabs you and never lets you go. Science and technology have made it so easy to find out everything we need to succeed. All the equipment to create yourself a greenhouse is only a click away.
You don’t even have to buy seeds if you’ve got some fruit and vegetables at home. Use the seeds you already have, and grow some chilies or tomatoes. Cultivate little lemon or orange fruit trees and transplant them outside when the weather’s right.
Who cares if the sun’s shining or not? You can tend to your plants at midnight if you want. Never mind the winter, you can eat homegrown summer fruit while it snows outside. Strawberries and cream for Christmas sound great, doesn’t it?
We’re slowly but surely becoming more self-sufficient and turning our backs on mass production and food we cannot trust. We’re eating vegetables we know are free of preservatives and chemicals, and beyond suspicion, because we grew them ourselves. The food we grow won’t stay fresh forever because they won’t be full of preservatives. But that’s the way it should be if they’re grown naturally.
There’s never been a better time to turn the extra space at home into your own Eden. Grow a little apple or fig tree, or anything you want.
But remember, once you start, you won’t have an excuse to avoid garden duty again because it’s raining or snowing or windy outside.