Growing with HPS Lights

HPS grow lights are considered the gold standard of indoor grow lighting, they have been used for decades and have grown a reputation for producing lush vegetation and HUGE plants.

There are many other options when it comes to growing plants such as CFL and LED grow lights. However today we are going to focus on MH and HPS grow lighting systems.

What are HPS Grow Lights?

High pressure sodium lights emit the red/orange frequency that flowering plants require to produce vast quantities of fruit. Any decent hydroponics store will sell you a HPS grow light kit which usually consists of a reflector, ballast, HPS lamp and timer or switch.

The bulb is screwed into the reflector which connects to the ballast, the ballast plugs into the timer and the timer into the mains power. That is your basic HPS grow light setup.

Are they suitable for all stages of my plants growth?

Many growers will use HPS lamps throughout their plants life cycle. Whilst their plants will still grow perfectly well it is recommended you use a MH (metal halide) bulb for the flowering stages. These bulbs emit the blue spectrum which is closer to “natural” conditions.

Fruiting plants grown entirely with HPS grow lights tend to become “scraggly” and with mismatched growth. MH promotes more all round growth especially during the vegetative period.

If you can get an MH bulb and use it for the vegetative stages of your plants life cycle, this will ensure your plants get a headstart when entering the flowering stages at which point you can switch to a HPS bulb.

You do get dual spectrum HPS bulbs which incorporate the blue spectrum that your plants require. This is certainly better than using pure HPS throughout the whole process however they are nowhere near as powerful as MH bulbs on their own. If you want the best growth for your plants use MH for vegetative and HPS for flowering.

How do I setup HPS grow lights?

It’s simple, plug it in and hang the HPS grow light above your plants. See this article for more information on how close you should put your light to your plants.

As previously mentioned you will need a reflector, ballast, timer & bulb to get started, you should also invest in a set of adjustable light hangers. A piece of string will work just as well but it will save you a lot of messing around as your plants grow and you need to raise your lighting.

What are the benefits of using HPS grow lighting?

One of the major benefits of HPS grow lighting is the sheer amount of power they can produce. A standard 600w grow light is suitable for 5 or 6 plants. Their relatively low upfront cost also means they outperform LED and CFL grow lighting at least initially.

Another major benefit is that there’s a wealth of knowledge out there. People have been using HPS for decades and the chances are that if you’ve got a problem someone else has experienced it too, a quick Google search will probably turn up a solution for any problem you have.

Finally HPS grow lighting is a mature technology unlike the much talked about LED. Basically you know what you’re getting with HPS/MH, some LED manufacturers make over confident claims and have no evidence to back it up.

What are the disadvantages of growing with HPS?

One of the major problems experienced with HPS lights is the amount of heat they produce. This can be dealt with by using extra extractor fans or air cooled lighting but these are expensive, especially if you’re using multiple HPS lights.

If you don’t have much vertical space HPS lighting may not be the right choice for you. These lights need to be placed 12-20 inches above your plants, add that into the height your plants will grow and you’ll quickly run out of space especially if your growing in a cupboard.

Finally, electricity costs can quickly add up with HPS lighting systems. A typical 600w light will cost anywhere from £30 to £100 to run, this is entirely dependent on what you pay for electricity. Add in a couple of 600w lights all the required cooling equipment and you’re electricity bills will start to spiral.

Will my home burn down with HPS lights?

There is a lot of misinformation out there regarding the safety of high pressure sodium lights, mostly caused by silly gardeners who don’t know how to set them up correctly or have bought some cheap chinese imports without CE & ROHS certification.

Here are some tips to reduce any risk:

• Don’t use cheap plug in timers, they’ll just melt
• Get a heavy duty timer with a switch
• Even better get a contactor switch
• Place the ballast on something which isn’t flammable (concrete, wooden blocks)
• Keep your grow room free from flammable products
• Make sure your smoke alarms work correctly
• Keep a fire extinguisher on hand just in case

How many HPS lights do I need to grow X amount of plants?

This isn’t an easy question to answer, it’s a bit like “how long is a piece of string” – we have went into this subject in some details here.

Can I get a dual spectrum HPS lighting kit?

Many manufacturers now offer a range of high pressure sodium bulbs with high PAR outputs, this means your plant can absorb more of the energy emitted by the light. For the best results get a metal halide bulb for vegetative growth and use HPS for flowering.

Magnetic vs digital ballasts – which is best?

Again we’ve covered this before. A magnetic ballast is usually 50% cheaper than a digital one but the old adage of you get what you pay for applies here. Digital ballasts will run cooler, longer and more silently than their analogue counterparts but cost double the money.

Digital ballasts are much more efficient and will result in less bulb replacements and in some cases produce more lumens. If you have the cash grab a digital ballast, if not a magnetic one will work just fine.

Do I really need a 600w light?

The 600w grow light is by far the most popular wattage but do you really need that much power? By a rule of thumb you want 100-150w of power per plant, so if you’re growing more than 5 plants grab yourself a couple of 600’s or a 1000w, if you’re growing less then think about getting a 400w or 250w.

Ready to shop for some HPS grow lights?