Lights & Plants

Plant growth, harvest, potency and even the time to flower are all dependent on the light they receive. Light quality, intensity and duration are all important. The following is a brief introduction to plants, light, lumens and PAR.

Light is a plants food, nutrients are only building blocks for the plant cells but it is light that provides the energy - so how does it work?

When light falls onto leaves it triggers the process of photosynthesis, which in simple terms is the process of turning light, which is radiant energy, into chemical energy. The amazing process of photosynthesis, turning light energy into chemical energy, is one of nature’s wonders. This energy transfer happens inside the plants cell structures called chloroplasts. The basic components of chloroplasts are individual membranous sacs which contain fats, proteins and pigments (stay with us - it is worth knowing!)

Pigments & Chemical Energy

Pigments play an important part. They absorb light in the photosynthesis process of turning light energy into chemical energy. Chlorophyll, for example, is an important pigment which absorbs red and blue wave lengths. There are different types of pigment and each absorbs different wavelengths of light. The light absorbed by the pigment causes a reaction, which produces chemical energy (it makes electrons out of the light, and the electrons use their charges to make sugar energy for the plant)

For those interested in the current theory of photosynthesis, it works something like this ~

The chemical energy produced by the chlorophyll (pigment) from light is sufficient to split the water molecules apart. This provides units of hydrogen (H) and hydroxide (OH). The hydroxide combines with carbon-dioxide, which is absorbed from the air, to produce carbohydrates, which provides the energy for plant growth. (and you thought there was nothing going on in your plants ~ for more details visit your library!)

So to summarise ~ light falls on the leaves which convert it into electrons and the plant uses these electrons (electricity) to make energy as sugar.

Light & Light Measurment

Light, its intensity, quality, its colour, spectrum, wavelength are therefore all-important factors, but how do we measure light and what are the most important components?
Light is measured in photons (which we, or at least I, do not really understand). Light actually hits objects, just like a spray of water, and the sun emits lots of light photons ~ to give you an idea of how many; the sun hits our body with over 12,000,000,000,000,000,000,000,000 photons every second and a plant needs about 20 photons to make a finished molecule of sugar.

So our scientists can count the number of photons hitting the plant and even predict how much of this energy will convert into flowers or fruits. Each industry has its own way of measuring light. Photographers use a light meter, the lighting industry uses lumens or lux and the gardening industry uses PAR. All are only measurements; the actual light coming from a lamp or the sun does not change ~ only the methods we use to measure are different.

Light Spectrums & Colours

Light from the sun is ideal but it is not the same as artificial light, where output quality, spectrum etc varies upon the type of lamp and how it is used. Many growers think that more lumens = better growth / yields, when in fact artificial light, even at its best in a HID or HPS lamp in not so good in terms of colours. Much of the light from the bulb is not used by the plant, mainly because it is not in the 400 to 700 nw (nanawave) spectrum, and plants can only see and use light in this range. Light quality and its colours are as important as lumens.

Light, as seen by plants is not a single colour but separate bands of active colours and the plant senses each colour-band of light as a separate signal. Each band of colour has a different effect on plants and the following are only a few of the functions which each band of light promotes.

Blue Light (350 – 500 NW) powers chlorophyll production, powers cell actively, energies the stomata movement and makes the plant follow light.
Green / Yellow Light (500 – 650 nw) ~ not much action from these bands of light.
Red Light (600 – 700 NW) makes sugar from CO2, powers chloroplast production, signals light and dark times among other functions.
Strong blue and red light photons (as above) are also needed for good carbon dioxide uptake.

The PAR scale measures all these coloured photons between 400nw & 700nw, the critical range for plants, as this is only range that plants can use light. If it is not in this range then it is wasted light.

PAR

For growers PAR is all-important ~ and as important as lumens! PAR stands for > Photosynthetic Active Radiation. Photosynthetic, the light sensed by a leaf pigment. Active, the light that causes the leaf pigment to become active for making energy Radiation, another word for light & photon energy
PAR is a measurement scale used internationally as a metric light measurement and is becoming more and more relevant to growing and greenhouse light measurement. Why is it important to you? PAR is the measure of light that a plant actually senses and uses, and it is the light the plant sees and can use that is more important then the actual output lumen of the grow lamp!

* A large HID lamp may give out loads of lumens, but if it is too far away from your plant most are wasted (remember light intensity diminishes with distance) In addition the light a plant can use from these lamps is limited because the plant cannot see or use it because it is in the wrong spectrum.
So the main value of the PAR measurement is that it is the only measure that takes into account the actual light and light colours that the plant uses to energise its pigments and generate sugar energy, and it’s the sugar that makes your plants grow and produce such sweet fruits!

PAR and Fluorescent Lamps

In the past fluorescent lamps were always known to have excellent "daylight" colour output but not the same photon power as HID / HPS lamps. The spectrum from fluorescents was ideal for propagation/seedlings but not for real time growing, because they were small watt versions and did not have the lumen / photon output. (i.e. an average household fluorescent tube is only about 35 watts. Nice spectrum but low light output! )

HID and HPS lamps have large lumen / photon output but are poor on colours omitted, but these lamps were the best available lamps at the time. However they do generate lots of heat and can be expensive to operate. They also need separate ballasts, control contacts and systems.

Plantagrow CFL Lamps (CFL=Compact Fluorescent Lamps)

The development of high-output compact fluorescent means you can now get the correct colour spectrum, always associated with fluorescents, but with much higher light output. This means that CFLs are now capable of much, much higher lumen output with all the benefits of the ideal, spectrum output.

Photon strength is still not as strong as HID Lamps (although with our new reflectors we are getting there) but because these new lamps generate much less heat they can be placed just inches of the leaves, and this is a very, very important factor when using grow lamps

Light Intensity

Light intensity diminishes the further it has to travel. This is the same for HID, CFL or your normal household lamp. If you hold a light meter up close to any lamp and then slowly lower the meter, even a few inches, you will see the light measurement reduces dramatically. (If you can borrow, beg, steal or get access to a light meter please try this ~ you will be extremely surprised at the rate at which the light intensity reduces over a short distance)

Light from an HID or HPS lamp reduces by half for every foot it is away from the plants. So if your lamps are 2’ or 3’ above your plants much of the light is wasted. The problem with HID lamps is they are so hot you cannot place them close to your plants and much of the light, and your money, is wasted.

One benefit of using high-out put CFL’s is that they do not generate as much heat and can be kept almost on top of the plants producing the exact 100% PAR light, with no loss of intensity. So if you position these new lamps close to the leaves you get the benefit of 100% PAR light in the correct 400nw to 700nw range, giving the plant the correct light colours and light quality.

Growing With Plantagrows

Plantagrows can be used to grow seeds and to propagate cuttings. They can also be used as the main lighting system for plants in the vegetative and flowering stages. The secret to growing with Plantagrows is to position your lamp or reflector just an inch or two above your plants.
(We use Easy-Roll Reflector Hangers and adjust the reflector height a small amount each day or so. We keep our Envitolites no more than 1" above the plant top.) Positioning these new compact lights directly above the plants maintains light intensity, no lumens are lost and the PAR / Spectrum is 100%, which is like natural sunlight. The plants get all the lumens they need with the light being in the correct spectrum.

Plantagrows are available in 2 models: Red 2700k (kelvin) and White 6400k (kelvin)

Red 2700k 125w lamps are used mostly for flowering. Many growers also use these lamps as a supplement to ‘hang’ by the side or in between plants when flowering. They can be used with HPS lamps, as a supplement or by themselves. We use them 100% and no longer use HPS lamps.

White / blue 6100k 125w lamps can be used for propagation and vegetative growth.

Some red light in the vegetative light mix is also recommended, as is a little white / blue light in the flowering mix. With different combinations of red and white lamps growers can obtain the ideal lumen output and spectrum required for excellent results in all stages of growing.

Plantagrows provide 100% PAR, which is such an important factor and it is important to be able to calculate the PAR values obtained from your grow lights and how much light your plants need to give maximum yield. If you are using HID / HPS lamps you should contact your supplier and ask them about PAR output, it is important that you know this as well as lumen output.

These brief notes are to only give you a very brief introduction into how plants work, how light is measured in horticultural world and the importance of PAR as well as lumens. I hope it stimulates you to learn a little more about lights, plants, pigment, PAR and produce!

Plantagrow Summary

Plantagrows are effective, energy-saving, reliable, low heat generating horticultural grow lamps, giving excellent results and lower operating costs for all indoor growers.

Plants need light in the correct spectrum, which is proven to be between 400 & 700 Nana Wave, and Plantagrows produce high output light in exactly this spectrum. There is no wasted light, unlike HID and HPS lamps were much of the light cannot even be seen or used by the plant.

Plantagrows give 100% PAR (Photosynthetically Active Radiation) high output light and are used successfully for all propagation, vegetative or flowering stages.

Plantagrows do not generate excessive heat and can be used directly over plants. This is the secret of growing with Plantagrows, positioned directly above, just 3 cm or 4 cm, the top of the plants! Unlike HID lamps, this new generation, grow lamps will not burn your plants.

This is a real advantage compared to growing with HID lamps, as there is no wasted light, which occurs when HID lamps are positioned high above plants. Plantagrows give 100 % PAR, correct spectrum, high lumen light directly on top of your plants - where they need it!

• Self Ballasting Lamps - simple to install or wire
• 100 % PAR in the correct spectrum for growing
• Generates much less heat than HID Lamps
• Energy saving lamps give lower operating costs
• High Lumen Output ~ Long Life Operation

125W and 200W Plantagrow are available in 2 models:
* 6100K Propagation & vegetative growing
* 2700K Flowering stage growing

* We are currently waiting for the independent results of a technical research program carried out by Sheffield University on comparisons (lumen, PAR, spectrum output, heat generation, operating costs etc) with HID / HPS lamps. The same research will monitor grow results using both types of lamps. We are extremely confident that the results of this research will surprise many growers and confirm that Plantagrow / CFL lamps which provide high-output lumens with 100% PAR will become the next generation of light systems for all growers.

We hope these brief notes have given you an insight into light and how plants see and use it. PAR is all-important and is becoming the measurement used by growers worldwide. For those of you interested in learning more about lights and PAR I suggest you purchase Graham Reinders book ‘The Secrets of High Yield Plants’.