Adding More Light Halfway Through Flower?

What is supplemental lighting? Supplemental Light is the use of many different light colors and intensities during certain phases of plant growth. Supplemental Lighting can be used to control the color of the plant produced; it can also be used to help plants grow faster and healthier.

Lighting, generally referred to as grow lights, is one of the most important aspects of indoor plant production. Grow lights are used to provide light for the growing area which can simply be providing light or adding more light but it is also using light that affects plants beyond photosynthesis. Light colors are actually light frequencies; different light frequencies (colors) will affect plant physiology. So specific colors/types of light can be used during specific growth phases to improve growth.

When understanding supplemental lighting, the first question to ask is what do you want to achieve with supplemental lighting (such as flowering or vegetative growth)? Each type of light used must be adjusted for the amount of light they give off; therefore, specific wavelengths need to be targeted.

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Best light spectrums for supplemental lighting?

Red and blue lights are the most important types of light for photosynthesis. These two colors are key to photosynthesis, so you’ll want your grow lights to have a large percentage of red and blue light. A good rule of thumb is around 70-80% of light should be in the red and blue spectrum.

Utilizing specific technologies and specific wavelengths of light is the key to maximizing your indoor garden’s production. By increasing red wavelengths, you can help induce flowering. Increasing blue wavelengths can increase the rate of growth between nodes.

A secondary way to manipulate the lighting is by using two separate bulbs from different spectrums. In this case you’d have a metal halide bulb and a bulb that produces purple and blue light (Ceramic Metal Halides are an example of these). Combining these bulbs creates a white light which suppresses vegetation and promotes flowering. Using two lights together – one for vegetative growth ( MH ) and one for flowering growth ( HPS ) provides the best results.

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Ultraviolet light

Supplemental lighting targets all spectrums of light to boost productivity. Supplemental light contains both blue and red wavelengths, ultraviolet (UV) as well as infrared (IR) and far-red waves to provide a healthy harvest. Narrow bands of UV and IR lights can be used in conjunction with other light sources to increase yields across all plants, new and old.

Supplemented UV light

Using a grow light with a high UV output during this process can help to harden plants more quickly and safely. In addition, using a purple-spectrum light during the initial stages of growth will encourage young plants to produce extra chlorophyll needed for healthy growth. Purple-spectrum lights can also be used in conjunction with white or blue wavelength lights as a way to reduce the stress placed on plants when they are moved from indoor setups to gardens.

Supplemental UV lights, including several varieties of T5 Bulbs, now make it possible to greatly reduce or eliminate the hardening-off process. Not only that, but by your plants being able to bask in all the same health-producing rays they receive while growing indoors, you can actually speed their growth rate right from the start! Imagine how much money and time you’ll save using this method. Read on for all the details about hardening off your new cannabis plants.

The UV-produced phenolic compounds, flavonoid pigments, and resins act as natural sunscreen for plants. When the UVB light is removed, the plant stops using these substances as protection and they remain in the plant providing color and flavor. Increased levels of oil production are found to occur when excess UV light passes through the plant. The UV lights used in our systems produce wavelengths at or around 290nm and 313nm, which are known to increase cannabinoids such as THC when present in high levels.

In many cases, UV light can be used to replicate or augment natural light producing equally amazing results. Keep in mind that light must be purchased in the same PAR and PPF values as the growing area’s lighting system.

Red light

Developed from red and blue LEDS, the far-red spectral range is perfect for crops like tomatoes. Tomatoes are often misclassified as short-day plants because they do produce fruit when exposed to continuous light of under 12 hours per day (usually grown indoors under lights). However, short day doesn’t mean that they don’t benefit from far-red light. Because photoperiodism is involved in the flowering cycle of tomatoes, exposure to far-red light will encourage

Really, the best way to use far red light is by doing it before your lights go off for a considerable amount of time. So for example, if you are running a 20/4 light cycle, then you want to run your far red light for the last hour before the lights turn off. This means that you will be getting about 20 minutes of light from that 730nm LED light bar in the flowering stage.

How intense should supplemental lighting be?

This means that the light intensity decreases with increasing distance squared. In practical terms, this means that if you are growing in a 1x1m² tent, and move your plant from the center to the edge, you will decrease the yield by an average of 16%. To avoid this problem, you can use supplemental light even on a full spectrum grow light.

To achieve even coverage, you need to provide supplementary light. Thankfully, this is easy to do, and can be done with large LEDs on the top and bottom of your garden or with several small LEDs placed around its perimeter. Both methods have their own merits and require different amounts of electrical power.

It is important to think about using the right lighting to increase the quality of your indoor grow. Indoor plants need a certain amount of light intensity to grow properly. The more intense the lights are, the more powerful each photon will be and the faster each plant will grow.

A full spectrum (five band) setup will help provide the growth that you want but has to be planned well. Especially if you are talking about a large garden, it can get expensive this way. You can however use low-wattage, low-heat options like LED grow light strip and T5 single bulb fixture types for side lighting to increase healthy leaves and plant growth.

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How to use supplementary lights for cannabis?

Now that you’re feeling more informed, let’s get into the real work. Let us walk you through how to implement supplementary lighting so that your plants don’t have to suffer from an uncomfortable lack of light.

It should be noted that different strains of cannabis will respond differently to these lights. Even if you’re growing the same strain, a different type of light may work better for one plant or another. Experimentation is important if you’re trying to figure out what works best for your grow setup. Make sure you have reflectors or built-in reflectors in place so you’re definitely getting the most out of your LED lights.


HPS lighting works on the simple principal of high pressure sodium. The lights burn at a very high temperature and, as such, produce a lot of heat which can damage sensitive plants if positioned too close. However, if used correctly, they can provide the correct spectrum to promote strong vegetative growth and flowering. They can be placed closer to the plant canopy after a cooling system has been implemented into the grow room.

Light intensity and spectrum or color is something to be aware of. HPS lights, while powerful, cause a lot of photochemical stress, which can lead to added plant stress and growth issues. Side lighting with more blue frequencies of light is a great supplement for HPS to give your plants the light its looking for without adding excess heat to the grow.


Metal halide lights have a very blue coloration, usually Daylight or more accurately Cool White. They are great for growing plants and are found in almost all indoor gardens. The light given off by MH lights is more blue, which is optimal for plant growth. This spectrum promotes vigorous growth and prevents stretching and spindly growth. MH grow lights also provide the best spectrum for germinating seeds and clones.


These lights are significantly more efficient in regards to output per watt, thereby eliminating the need for large and heavy ballasts. Also, unlike many other types of grow lights, CMH can be used for supplemental purposes, such as providing light to supplement your indoor garden.

An HPS bulb typically is made to be used alongside an MH bulb, or even two. The CMH bulbs allow you to spread your light out a bit more and, because of the lower power consumption, you’ll end up using less electricity while doing so!


As we move into the future the LED continues to gain popularity. From it’s origin as a small business light source, to more and more household uses, soon it will be the best option for all of our lighting needs. LED stands for light-emitting diode. Changing the specific chemical makeup of a traditional semiconductor material allows that material to emit light when energized.

Unfortunately, a lot of LED fixtures aren’t designed to provide optimal light wavelengths for plant growth. In addition, typical LED grow lights don’t have the light penetration that you need for plants to thrive. However, the latest iterations do offer much better options and can satisfy most growers. Just make sure to thoroughly research what you buy before buying it!


T5 lights are one of the most versatile horticultural lighting systems available. Great for both small and large gardens and greenhouse applications, T5 grow lights are perfect for seed starting and cultivating new plants as well as nurturing already-established expandable plants.

However, T5 Fluorescent grow lights offer a fantastic range of spectral options and can be cheaply configured to provide better coverage for any size of the garden. T5 lights can also easily replace any other types of fluorescent grow lights such as tube-based models. You just need to have the right PAR spectrum and a reflector to direct the light to the plants you want to focus your growing efforts on.

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Quick Flowering Seeds

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