For years, HPS technology has proven itself one of the best grow light choices for indoor and outdoor gardeners who want big, consistent, and predictable harvests. In short, HPS delivers.
In this guide, we have gathered what we consider to be the most important information to help you choose the right HPS bulb for your garden. We’ll guide you through different lamp sizes, their applications, prices, and a few recommendations of what we consider to be the best HPS bulbs.
If you’re in a hurry, these are our picks for the best choices for HPS bulbs:
1000w DE HPS
No good recommendations
What is a HPS Light?
Invented in 1964, HPS stands for High Pressure Sodium. It's a light technology that has shaped how we cultivate indoor plants in a huge way. HPS bulbs consist of a narrow arc tube supported by a frame in a bulb. To improve efficiency, the arc tube is kept at an extremely high pressure. Sodium, mercury and xenon are usually used inside the arc tube in order to improve the light spectrum.
The most common way to start the bulbs is with a pulse start. This pulse starts an arc through the xenon gas and the lamp turns sky blue. The arc then heats the mercury which then lights up, giving the bulb a bluish color.
As the bulb heats and the sodium starts to vaporize it strikes an arc over 450° F (240° C). The sodium is then mixed with other impurities to create a more "white" light. Mercury helps add a blue spectrum light to the pure yellow of the sodium.
Why Are HPS Lights So Popular?
Usually HPS technology is chosen because it is a powerful light that provides a spectrum that plants can use well, specially for flowering, blooming, and fruiting crops. HPS bulbs also come in many different sizes, making them a flexible pick for your indoor garden.
Although there are 150 watt bulbs and 250 watt bulbs, those usually come with their own ballasts and reflectors in an all-in-one kit. When it comes to bulbs, the most commonly used sizes are 400W, 600W and 1000W.
As a general rule, 400w HPS bulbs are the most common, 600w HPS bulbs are the most efficient, and 1000w HPS bulbs are the most powerful (but also the hottest).
Before we continue, here's a rundown of the good and bad points of running an HPS grow light:
- Good spectrum for flowering and fruiting
- Affordable and reliable
- High lumen output at 80-160 lumens per watt
- High PAR efficiency when compared to fluorescent lights
- Different sizes for different spaces
- They produce a LOT of heat and need cooling
- Suffer significant degradation over time
- Require a ballast and reflector
HPS Spectrum Output
Different grow lights produce different spectrums of light. Plants grow responding to the color spectrum of the light they’re receiving, this process is scientifically known as photomorphogenesis.
HPS bulbs emit a golden-yellow light that is specially good to maximize budding and flower production. Their spectrum what makes HPS bulbs emit their respective golden colored light.
Here’s an example of what the usual HPS PAR spectrum looks like:
Note that we said “PAR spectrum." PAR stands for Photosynthetically Active Radiation and is light between 400 and 700 nanometers which is specifically used by plants at certain ratios for photosynthesis. HPS bulbs also produce a little light outside of the PAR spectrum, like infrared but this light is generally not useful for our plants and greatly contributes to heat production.
HPS bulbs tend to produce most of its usable light as yellow and red light. This is why some growers choose to supplement their HPS grow lights with Metal Halide (MH) lights which have a green-blue dominant spectrum for more balanced light spectrum.
Learn More: How Do Plants Use Light?
What is a Ballast and Why Do I Need One?
You can’t run an HPS bulb without a fitting ballast. At best you’re going to break the bulb, and in the worst case scenario you’re setting an explosion up.
A ballast is what powers your HPS bulbs. The ballast takes your input voltage and electrical current and regulates it into pulses within specific frequencies to enable your bulb to run efficiently and optimally, regardless of voltage fluctuations outside of the system.
The best digital ballasts should be able to keep your HID bulbs running optimally even if your input voltage suddenly changes.
For more information on ballasts and our recommendations, check out our Digital Ballast Buyers Guide.
Choosing the Right Wattage
As the size of your garden grows, so do your lighting needs. It's sometimes hard to figure out how much light you’re going to need to cover your grow tent or indoor growing space.
But as usual, we’ve got you covered. We’ve figured out what HPS bulb size fits best for certain areas.
150 Watt HPS Bulbs
Most 150W HPS grow lights come with their own ballast and reflector built-in. At 150 watts HPS don’t get very hot compared to the other bulb sizes. But this size of light is also the least efficient of all HPS bulb sizes.
Plant Distance: At least 6’’ or 15cm away from your canopy
Recommended Area: 1.5’ x 1.5’ or 0.45m x 0.45m
250 Watt HPS Bulbs
Just like 150 watters, most 250W HPS grow lights come with their own ballast and reflector built-in. Although it is easier to find 250W bulbs at the store, it is quite a task to find a reliable stand-alone 250w ballast.
Also, at 250 watts HPS bulbs start getting significantly hot, so remember to step up your cooling game in order to keep your plants healthy. This size is right between 150W and 400W in terms of efficiency.
Plant Distance: At least 10’’ or 24 cm away from your canopy
Recommended Area: Up to 2.5’ x 2.5’ or 0.75m x 0.75m
400 Watt HPS Bulbs
At 400 watts, things start getting productive. And very hot too. This size is the most commonly sold HPS bulb in the market, and this is no coincidence. At 400W we’re almost nearing the top-end of HPS efficiency, which means that although the bulb will emit a lot of heat it will also provide significantly more PAR light to your plants than a 250W bulb.
You can find 400W HPS grow lights as kits composed of a separate ballast, a reflector and the bulb itself for a very affordable price. They’re also available (although less common) as all-in-one grow light fixtures. We do not recommended as these tend to be less efficient than separate solutions.
Plant Distance: At least 14’’ or 30 cm away from your canopy
Recommended Area: Up to 3.5’ x 3.5’ or 1.1m x 1.1m
600 Watt HPS Bulbs
Generally producing around 90,000 lumens or 150 lumens per watt, 600w bulbs are the most efficient HPS bulb size of them all. This means that the 600w HPS lamp size converts the biggest amount of electricity into usable light of them all.
This bulb is also the one with the least relative waste (heat).
Plant Distance: At least 18’’ or 45 cm away from your canopy
Recommended Area: Up to 4.5’ x 4.5’ or 1.4m x 1.4m
1000 Watt HPS Bulbs
At 1000 watts, these bulbs are more efficient than 400 watt bulbs, but less efficient than 600 watt bulbs. This efficiency decrease is significant enough that some growers even recommend to try using two 600 watt lamps for your growing space before making the jump to the 1000 watt lamp.
With this said, we do have to recognize that at 1000 watt, there is no bigger and more productive single HPS lamp solution. And as its light output grows, so does the heat it produces.
Plant Distance: At least 24’’ or 60 cm away from your canopy
Recommended Area: Up to 6’ x 6’ or 1.8m x 1.8m
Double-Ended HPS Bulbs
Double-ended (DE) HPS bulbs are the latest HPS craze. Not only are they significantly increasing yields but they’re constantly recommended by almost every grower that tries them. Statistics show that these bulbs constantly outperform HPS bulbs by at least 10% in PAR light output.
These bulbs also degrade at half the rate of traditional HPS bulbs. Not only are they more productive, they also last longer!
Aside from use during blooming, fruiting and flowering production, double-ended HPS lights work a little better than standard HPS bulbs with bigger peaks in the red spectrum. Double-ended HPS bulbs also emit more ultraviolet (UV) and infrared (IR) light than traditional HPS bulbs.
HPS Bulb Brand Overview
While there are a million and one “brands” of HPS bulbs, most of these are Chinese knockoffs of extremely popular and high-selling brands that are more established in the market.
To avoid going on and on about obscure brands, this article will cover the following five brands only. These HPS bulb manufacturers are well known and well respected in the growing community.
EYE Hortilux – A “premium” manufacturer of horticultural lighting that is considered to be best in class by many indoor growers.
Ushio – A specialist in many types of industrial lighting, including horticultural lighting.
Digilux – A hydroponic-focused light manufacturer that is owned by Hydrofarm. Bulbs are manufactured in China.
Yield Lab – An up and coming bulb from GrowAce, an online hydroponic retailer. Best value, tied with Ushio and Digilux for a much lower price.
Sunmaster – A large manufacturer of grow bulbs for both hydroponic and general horticultural use.
HPS Bulb Review Roundup
Here we have a list of what we consider to be the best bulbs to buy. Since there are so many different choices and applications it became obligatory for us to dismiss some choices and favor others. But, after testing, reading specifications, and researching grower experiences, we're confident these are the top choices.
1000w DE HPS
No good recommendations currently
Best Traditional HPS Bulb
Best Overall: Eye Hortilux Super HPS
25% more light in the blue spectrum than traditional HPS bulbs (better vegetative growth).
17% more energy than traditional HPS bulbs.
Hortilux Recommends replacing the bulbs every 11-12 months for average performance. At this price range, a bulb (or many bulbs) every year becomes a noticeable investment.
Analysis: A bulb with a premium price tag that delivers constantly delivers results. Available in almost all sizes from 250w to 1000w options. It has been tested time and time again to be the top-end of traditional HPS bulbs. It comes with an enhanced spectrum, specially in those violet, blue and green parts and more overall par light production than the competitors.
Runner-Up: Ushio HiLUX Gro Enhanced Performance HPS
Analysis: With an initial PAR output of 1810 micromol/s this is the second best HPS Lamp you can buy without breaking the bank. This bulb comes with a custom spectrum with an increased blue and green output.
It comes in 3 sizes: 400W, 600W & 1000W, with the 600W option being the most efficient of all. This lamp also goes a long way before needing to be replaced with 24,000 hours of lifetime. The only downside is that it’s a little pricier than the EyeHortilux, it remains to be seen if the guaranteed lifetime justifies the tag.
Best (Easily Available) Double-Ended HPS Bulb
Best Overall: Ushio Pro Plus Double Ended HPS
Analysis: Ushio comes again! This time with their Pro Plus Double Ended HPS. This lamp is very close in performance to the Best of all Bulbs, the Phillips Green Power Plus DE (which is impossible to find). And this is the next best available Double Ended lamp out there with 2100 micromol/s of initial PAR and a guaranteed lifetime of 10,000 hours.
Best Cheap HPS Bulb
Analysis: These are very similar bulbs aimed at the same market range. They’re supposed to provide the standard no-fuzz HPS experience without any hitches. These bulbs will not disappoint anybody for their price.
Available in 400W, 600W and 1000W options, they seem to have an option for every grower. They boast the standard HPS spectrum and are both solid HPS choices for those looking for affordable bulbs.
We think the EyeHortilux is really your best bet if you’re looking for a reliable high-end product. Hortilux bulbs consistently come up at the top-end of every comparison done, and we know why. They have designed a custom HPS that outputs a more complete spectrum with more PAR light that all the competitors.
It’s even better when you consider that their prices aren’t really that bad either with Ushio bulbs being around 10% more expensive we think that Hortilux have found themselves an unmovable spot at the top of the market.