Quick answer: LED grow lights cost more upfront but use less electricity, run cooler and last longer — making them the better choice for most home growers in 2026. HPS grow lights are still worth considering if you want the lowest possible starting price and already have strong ventilation in place. The right pick depends on your tent size, budget and how long you plan to keep growing.
Choosing between an HPS and an LED grow light is the single biggest decision a new (or upgrading) grower makes — it shapes your electricity bill, your heat and ventilation needs, your yield, and your upfront spend. This guide walks through how each technology works, how they actually compare, and how to pick the right one for your space and budget.
How HPS and LED grow lights work
HPS (High-Pressure Sodium) is a type of HID (High-Intensity Discharge) lamp. An electrical arc passes through sodium vapour inside a bulb, producing an intense orange-red light. HPS needs a separate ballast to regulate the electrical current and a reflector hood to direct the light down onto the canopy. HPS is often grouped with CMH/CDM (Ceramic Metal Halide) lighting, which uses a similar arc-tube principle but produces a whiter, more blue-shifted spectrum — CMH is commonly used for the vegetative stage or supplemented alongside HPS. Browse our HID (HPS/CMH) Grow Lights range to see current kits and prices.
LED (Light Emitting Diode) grow lights use arrays of diodes, usually mounted on bars or boards, to convert electricity directly into light at specific, controllable wavelengths. Because LEDs run cooler and more efficiently than a gas-discharge bulb, most modern fixtures use passive heatsinks rather than fans, and the diodes themselves can be tuned to emit primarily the red and blue wavelengths plants use for photosynthesis, alongside white, far-red or UV supplementation. See our full LED Grow Lights range for options across every tent size and budget.
The spectral shape is really what sets these three apart. HPS puts out a sharp, dominant spike around the yellow-orange sodium line with comparatively little blue or green — great for triggering flowering, less useful for vegetative growth. CMH/CDM spreads its output much more evenly across the visible spectrum, closer to daylight, which is why it's favoured for veg or as a spectrum-filling supplement to HPS. LED is the most engineered of the three: manufacturers build in distinct peaks (commonly blue around 450nm and red around 660nm) with a broader "white" hump from phosphor conversion, plus optional far-red or UV channels — giving growers direct control over the ratio a fixed-spectrum HPS or CMH bulb simply can't offer.
HPS vs LED: the key differences that actually matter
1. Energy efficiency and running cost
This is where the technology gap has become most pronounced. Efficiency in horticultural lighting is measured in µmol/J (micromoles of usable light per joule of electricity) rather than simple wattage — two fixtures can draw the same power and produce very different amounts of usable light.
Independent horticultural research comparing red LED, blue LED and HPS fixtures measured photon-flux efficiencies of around 1.9 μmol/J for blue LED, 1.7 μmol/J for red LED and 1.64 μmol/J for HPS — LED already ahead on this measure, even though the HPS setup was found to convert overall electricity into plant growth slightly more efficiently once every loss in the system was accounted for. Older HPS/metal-halide fixtures typically sit around 1.8–2.2 µmol/J, while modern LED grow lights commonly reach 3.0 µmol/J and higher, and today's flagship commercial LED fixtures are pushing 3.1–3.7 µmol/J. In practical terms: a good modern LED can deliver the same (or more) usable light to your plants for noticeably less electricity than an equivalent HPS — this is usually the single biggest factor in the total led grow light running cost versus HPS over a full grow season.
2. Heat output
HPS bulbs run hot. That heat can be useful in a cold shed or garage in winter, but in most UK grow tents it means you need a proper extraction fan and carbon filter running continuously to keep temperatures in check, and you have to hang the light further from the canopy to avoid scorching leaves — which in turn reduces the light intensity actually reaching your plants. LEDs run much cooler at the fixture, so you can typically hang them closer to the canopy and get away with a lighter-duty ventilation setup, though you'll still want extraction for humidity and CO₂ exchange either way.
3. Spectrum
HPS light sits heavily in the yellow-orange-red part of the spectrum, which suits flowering/bloom well but is a poor match for vegetative growth, and it puts out a fair amount of light and infrared energy that plants don't use efficiently. CMH is often paired with HPS specifically to fill in the bluer wavelengths for veg. LEDs can be engineered to emit a full, tunable spectrum — many modern fixtures let you shift the red:blue ratio between veg and flower, and add far-red or UV channels, from a single fixture.
4. Upfront cost
This is where HPS still wins, and it's the main reason it hasn't disappeared. A complete 600W HPS kit (ballast, reflector, bulb) can be picked up for well under £100, whereas a comparable high-quality LED fixture covering the same footprint typically runs from roughly £150 up to £800+ depending on brand, wattage and spec. Based on current UK stock, HPS/CMH fixtures generally range from around £45 up to £595, while LED fixtures span a much wider range — from budget 720W panels under £100 up to premium 1000W-class fixtures around £1,000–£1,250.
5. Lifespan and running costs over time
HPS bulbs degrade in output over their life and are generally recommended for replacement every 12–18 months of regular use, plus the ballast is a separate component that can fail. LED diodes are typically rated for tens of thousands of hours and most quality fixtures come with driver warranties of 3–5 years, so while the initial outlay is higher, you're not paying for bulb replacements every season.
6. Coverage, canopy penetration and noise
HPS is a single, very bright point source, which gives it excellent penetration into a dense canopy from a single fixture — useful for larger single-tent grows. LED panels/bars spread light more evenly across a footprint from multiple diode points, which can mean less harsh hotspots but sometimes needs strategically placed fixtures (or under-canopy lighting) to get light deep into a thick canopy. Neither technology makes meaningful noise itself, but HPS setups typically need a noisier, higher-capacity extraction fan to manage the heat.
HPS vs LED grow lights: quick comparison table
| Factor | HPS | LED |
|---|---|---|
| Upfront cost | Lower (from ~£45) | Higher (from ~£95, premium £800+) |
| Running cost (electricity) | Higher per unit of usable light | Lower — better µmol/J |
| Heat output | High — needs strong extraction | Low — lighter ventilation needs |
| Lifespan | Bulb: ~12–18 months | Diodes: years, often 3–5yr warranty |
| Spectrum control | Fixed, red-heavy (pair with CMH for veg) | Tunable, full spectrum |
| Canopy penetration | Excellent (single bright point source) | Good, more even; benefits from multi-point fixtures |
| Best for | Budget-conscious growers, flowering stage, garages/sheds that need the heat | Growers prioritising running costs, heat-sensitive spaces, long-term setups |
How to choose a grow light: a step-by-step approach
- Work out your tent size and target yield. Bigger tents (1.2m x 1.2m and up) can justify a higher-wattage fixture of either type; small tents (under 80cm) are usually better served by a compact LED panel, since a full-size HPS kit will run too hot for the space.
- Be honest about your budget — both today and over 2–3 years. If you need the cheapest possible start and don't mind replacing a bulb annually, HPS wins on day one. If you're planning to run several grows over a few years, the lower running costs and long diode lifespan usually make LED the better total-cost-of-ownership choice.
- Check your ventilation setup first. If you already have a strong extraction fan and carbon filter, HPS heat is manageable. If you're working in a small room, a loft, or somewhere heat build-up is a real problem, LED will make climate control much easier.
- Think about what you're growing and the stage. If you're only running one light through veg and flower, a full-spectrum or switchable LED avoids needing to swap bulbs. If you're happy running separate veg (CMH) and flower (HPS) lighting, HID can still deliver excellent flowering results for the price.
- Match wattage/PPFD to your space, not just the label. Compare fixtures by their actual photon output (PPF/PPFD and µmol/J) rather than wattage alone — a 300W LED can outperform a 400W HPS in usable light depending on the fixture.
- Factor in the whole kit, not just the light. HPS needs a ballast, reflector and bulb (and usually more robust extraction); LED fixtures are typically closer to plug-and-play but check whether the driver is built-in or external, and whether it's dimmable. If you'd rather buy everything matched and ready to go, our Complete LED Tent Kits bundle a tent, light and extraction together.
What's currently in stock
Green Spirit Horticulture (Sheffield, with stores in Sheffield and Barnsley) stocks both routes:
- LED Grow Lights — 53 products from brands including Maxibright, Control LED, AC Infinity, Telos, DLI, Gorilla and Photon, ranging from around £95 up to roughly £1,250 for flagship fixtures.
- HID (HPS/CMH) Grow Lights — a smaller, focused range from Pulsar, Maxibright, Gavita, DLI and Newlite, from around £45 up to £595, including complete HPS kits and CMH lamp options.
Solar-Tech
| Fixture | Price | Efficiency | PPF | Coverage / notes |
|---|---|---|---|---|
| Solar-Tech 720W PRO ID | £199.99 | 2.7 µmol/J | 1980 PPF | 1.5m x 1.5m coverage; isolated internal driver; foldable; 3-year warranty |
| Solar-Tech 720W Lite | £149.95 | 2.5 µmol/J | 1750 PPF | Built-in driver, foldable 6-bar design, on-board dimmer; 3-year warranty |
| Solar-Tech 660W Lite | £149.95 | 2.6 µmol/J | 1650 PPF | Built-in driver, IP65 rated, 0–100% stepless dimming |
All three use an enhanced red spectrum tuned for flowering, run on Sanan diodes, and are compatible with the Solar-Tech Lighting Controller (sunrise/sunset simulation, temperature and humidity control, and smartphone control across up to 30 fixtures). They sit in the mid-range of our LED lineup on both price and efficiency — a solid step up from entry-level budget panels, at a lower price than premium fixtures like the Maxibright Daylight 1030W PRO or Telos Dynamic range.
Frequently asked questions
Is LED better than HPS for a grow tent?
For most home growers, yes — LED uses less electricity per unit of usable light, runs cooler, and the diodes last far longer than an HPS bulb. HPS still has a lower purchase price and excellent penetration into a dense canopy from a single fixture, so it can suit growers on a tight starting budget who already have strong ventilation.
How much does it cost to run an LED grow light versus HPS?
It depends on your electricity tariff, fixture wattage and hours run per day, but because modern LEDs typically deliver 3.0 µmol/J or more against roughly 1.8–2.2 µmol/J for HPS, an LED fixture generally needs meaningfully less electricity to produce the same amount of usable light over a full grow.
Can I switch from an HPS grow light to LED partway through a grow?
You can, though it's smoother to switch between grow cycles rather than mid-flower, since the two technologies have different spectrums and light intensities and plants can take a short time to adjust.
What size LED grow light do I need for my grow tent?
As a rough starting point, match the fixture's footprint to your tent size — a 60–80cm tent typically suits a 100–300W LED, a 1m x 1m tent suits roughly 300–600W, and a 1.2m x 1.2m tent usually needs 600–800W for strong coverage. Always check the manufacturer's stated coverage area and PPFD map rather than relying on wattage alone.
Do LED grow lights need less ventilation than HPS?
LEDs produce significantly less heat at the fixture, so you can often run a smaller extraction fan than you would need for an equivalent HPS. You'll still need extraction for humidity, CO₂ exchange and odour control regardless of which light you choose.
The bottom line
There's no universally "better" choice — it depends on your priorities. HPS remains a genuinely solid, proven option if your priority is the lowest possible upfront cost and you can manage the heat. LED has become the default recommendation for most home growers in 2026 because running costs are lower, heat management is easier, spectrum control is far more flexible, and fixture lifespans are longer — the main trade-off is a higher price tag on day one. If you're not sure which fits your setup, the team at Green Spirit can talk through your tent size, budget and ventilation before you buy — get in touch via info@greenspirit.ltd or 0114 275 3353.
