By Luke Sholl Reviewed by: Miguel Ángel Garcia


Most cannabis growers have multiple objectives in mind when planning an indoor grow. Drafting scenarios to achieve higher yields, increase THC levels, or simply to improve the overall health of a plant is an integral part of their hobby. This element of strategic planning involves the challenge to link knowledge of different scientific fields and to match those findings to a technical solution that helps to achieve predefined goals.

Besides dedication and passion, it is the willingness to learn that differentiates good growers from future experts – so let us try to grow the royal way and learn what it takes to cultivate cannabis of exceptional quality. Today, we are looking at fundamentals of physics, and learn how the light spectrum affects the growth of a cannabis plant.

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What is THC?

What Is The Light Spectrum?

The sun emits energy in the form of solar radiation including gamma rays, x-rays, ultraviolet light, visible light, and even radio waves. Life on Earth is only possible because the ozone layer blocks this radiation, and reflects most of it back into space. This filtering process only allows wave lengths between 300nm and 2500nm to reach our plants and an even smaller portion of this light is visible to us. The visible spectrum is a part of the light spectrum, and ranges from 380nm to about 750nm.

  • 180-280nm - UVC: Extremely harmful and luckily almost completely absorbed by the ozone layer
  • 280-315nm – UVB: Cause of sunburn and suspected to increase THC levels (!)
  • 315-400nm – UVA: Not absorbed by the atmosphere, commonly known as black light
  • 380-750nm – The visible light spectrum: Bands of wave lengths represent visible colors
  • 700nm-0 inches – Infrared light: Not visible above 750nm but noticeable as heat on our skin
What Is The Light Spectrum?

Color Temperature (Kelvin) And How It Affects Your Plants

When shopping around for a grow light, you will likely come across the term "color temperature". This is essentially a way to describe the light appearance provided by a bulb, and is measured in Kelvin (K).

Color temperature doesn’t mean the physical temperature of your light, but the degree of warmth or coolness of a light source—the “visual temperature”. When a light has a higher degree of Kelvin, it has a more blueish appearance. Thus, we call it a “cool” light. On the other hand, a bulb with a lower degree of Kelvin emits a “warmer”, reddish light.

Is Color Temperature The Same As Light Spectrum?

In a strictly scientific sense, no. Color temperature is normally used as a way to describe how the light produced by a lamp looks to the human eye. For some types of lights, such as LEDs or fluorescent lamps, it doesn’t describe a light’s spectral distribution of wavelengths.

Without going too deep into physics here, the light from an incandescent bulb radiates light spanning the entire visible light spectrum. The white light from the bulb is the result of a mix of wavelengths (colors in the spectrum) “contained” in the light.

Other lights, such as LEDs or fluorescents, may emit light from a number of narrow wavelengths, with gaps or peaks within the spectrum. In other words, even if the light appears the same to the eye, it may be missing certain wavelengths (colors) that plants require for healthy growth.

Because LEDs tend to emit light in a very narrow color spectrum, LED grow lights are usually outfitted as “full-spectrum” setups. They consist of a number of different-colored LEDs that together cover most of the necessary spectrum for cannabis plants. These full-spectrum LEDs are comprised of different reds and blues, often mixed with additional white LEDs. Others, newer LEDs such as COB lights (Chip on Board), are an array of LED chips packed together that it could help to get a better spectrum, but always the spectrum must be studied.

Where Does Kelvin Come In When Choosing A Grow Light?

For vegging your cannabis plants, go with a cool light, one that emits a "daylight" color with a high Kelvin of 5,500–6,500K. For flowering, a warm light with a reddish tone, about 2,800K, is optimal. You can also find grow lights with a “best of both worlds” color temperature of about 3,500K, which you can use for both vegging and flowering.

How The Light Spectrum Affects Growth

Every organism living on Earth needs information what is going on around them to react to environmental changes, and ideally, get a slight advantage over other members of their species regarding natural selection and evolution. Interestingly, cannabis plants receive a lot of their information from the light they’re exposed to, and almost instantly react to different bands of wave lengths - a complex topic to fill books with, but let us focus on the basics first.

  • Vegetative Stage – “Blue” light for healthy leaves (range: 400-500nm; ideal: 450nm)
Cannabis Light Spectrum

During the vegetative stage it is recommended to aim for as many leaves as possible, and to make sure plants stay rather compact, don’t stretch too much, and develop strong stems. Indoor growers tend to use metal halide bulbs, compact fluorescent lamps (CFL’s), or T5/T8 lighting fixtures with a blue band of light for the first few weeks to achieve these goals. When cannabis grows in nature, the high angle of the sun in spring and summer allows more “blue” wave lengths to penetrate through the atmosphere, a signal for cannabis plants to grow strong, large and healthy leaves.

  • Flowering Period – “Red” light for giant buds (range: 620-700nm; ideal: 660nm)
Cannabis Light Spectrum

When cannabis plants enter the flowering period, highest yields can be achieved by exposing them to a light spectrum that contains lots of “red” wave lengths to promote budding. The rate of photosynthesis peaks when plants are subjected to “red” wave lengths of 660nm although latest NASA findings suggest that even “green” wave lengths, which are not associated as a major factor in photosynthesis, can also have an impact on how plants grow. Seeing a cannabis plant as simple photosynthesis factory is consequently a little hasty. But for now, choosing a lighting solution with a high degree of “red” in its spectrum remains the best way for growers to imitate the shallow angle of the sun in late summer and fall.

Increasing THC Level With UV Light—Myth or Reality?

As we’ve outlined already, light is measured in nanometers (nm), with the visible spectrum of light sitting between 380 and 750nm. However, UV sits under the lowest end of the visible spectrum, invisible to the naked eye. But, just because you can't see UV doesn't mean it isn't useful, especially when it comes to growing cannabis plants.

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In fact, research suggests[1] that boosting UV exposure could increase THC levels, making for more potent buds. There's compelling real-world evidence as well, especially when you look at where some of the world’s most potent cannabis comes from.

The Rif Mountains in Morocco and the Beqaa Valley in Lebanon are home to some of the planet's dankest hashish. What do these areas have in common? They are both close to the 30°N latitude parallel (where the sun offers a good light spectrum for our crops), and they're both located at a high altitude. When it comes to UV light, a greater altitude equals increased exposure.

What Types of UV Light Are There?

For cannabis growing, you need to know about three types of UV light: UVA, UVB, and UVC. Although all three belong to the UV spectrum, they don't all have the same effect on plants, and some can cause more harm than good if not implemented in the right way.

Before we outline the best ways to add UV to your cannabis grow, let's quickly explain each type.

What Types of UV Light Are There?
  • UVA (315–400nm)

UVA accounts for over 95-99% of UV light reaching the Earth, making it an integral part of our natural environment. If you're growing cannabis outside, you needn't worry about boosting UVA levels—your plants will already be getting plenty!

Unfortunately for humans, prolonged exposure to UVA can increase skin cancer risk, so make sure you protect yourself with sunscreen. However, for our bud-producing friends, UVA may help boost THC level, with an increase in exposure being most important during flowering.

  • UVB (280–315nm)

While roughly 1-5% of the sun's rays are UVB (parallels, time of day and season depending), it could still prove a powerful ally in the quest for greater THC levels. However, it's important to be careful with UVB supplementation, as every plant species reacts differently to prolonged exposure. In cannabis, UVB may help boost terpene and cannabinoid production, but only during the last few weeks of flowering.

In humans, UVB is an excellent source of vitamin D, which is vital for well-being. However, it does come with the same caveat as UVA, in that long-term exposure may increase the risk of skin cancers. As a grower, the key is providing the right exposure for your plants while ensuring you stay protected.

  • UVC (100–280nm)

Our third and final ultraviolet light spectrum is the notorious UVC. We say notorious because UVC is, in fact, the most dangerous of the three, and not useful to humans or cannabis plants. Grow lights shouldn't emit UVC (be very cautious if they say they do), and 0% of UVC rays reach the Earth's surface.

You and your plants should naturally avoid exposure to UVC, and that's the way you want it to stay. Just remember: UVA is good, but be careful with long exposure times. UVB also pretty good but be EXTREMELY careful with exposure times and dosage, and finally, UVC is very bad, so try to avoid it at all costs (if you are not a proffesional with adequate protection and equipment).

The Advantages of UV Light for Cannabis Plants

We've alluded to this already, but UV light provides several potential benefits for cannabis plants, including:

  • Increased cannabinoid production (THC)
  • Better resin generation
  • Enhanced resistance to pests and bacteria
The Advantages of UV Light for Cannabis Plants

The Disadvantages of UV Light for Cannabis

Fortunately, there aren't many disadvantages to using UV light. But, if you don't manage the exposure adequately, you may find the following:

  • Overexposure can stunt growth
  • Possibility of decreased CBD levels (more research is needed because it depends if we use UVB or UVA radiation and in what dose)
  • Low return on investment
Cannabis Light Spectrum

Can You Use UV Light for Indoor Cannabis Growing?

Of course! The short answer is, you can use UV light for all types of indoor cannabis growing. However, the long answer is, you'll need to do a little planning, and may need to buy some extra equipment to make the most of its benefits.

Some grow lights give off some a degree of UVA, but if you want to maximise potential gains, you'll need to purchase a dedicated UV lamp. The majority of cannabis plants will respond well to UV supplementation.

Still, it does depend on their genetics, so keep that in mind if you don't notice any real increase in resin production. It's also advisable to hold off on prolonged UV exposure until flowering. This crucial period is when we want to boost the plant’s focus on cannabinoid, terpene, and resin production.

You'll also need to consider the space required to hang a UV light (just like conventional growing lights, there's an optimal and suboptimal hanging height). And finally, if you're going to use dedicated UV lights, do it safely! UV-resistant glasses are a must, as are long-sleeve tops if you are tending to plants regularly with the lights on.

How to Provide UV Light to Indoor Cannabis Plants

All three of the major types of grow light (HID, LED, and T5) will provide your plants with varying degrees of ultraviolet light. To make the most of UV's bud boosting potential, you'll need to consider the following for each type.

  • HID

High-intensity discharge light bulbs (HIDs) are the most common type of cannabis grow light, and, fortunately, are an excellent UVA source. However, HID grow lights can lack UVB, so you have two options—run an additional UVB light alongside your HIDs, or replace the bulb with a T5 fluorescent glow bulb.

Both will have a similar impact, but if you go for a supplemental UVB light, you’ll need to hang it at the same height as your existing HIDs to prevent bleaching.

How to Provide UV Light to Indoor Cannabis Plants
  • LED

LED grow light technology has come leaps and bounds in recent years. Many feature dedicated veg and bloom settings, while others include special UV diodes. If you want to keep your indoor grow simple, keep an eye out for these all-in-one models.

There isn't much more to say about LED lights. They're a great all-round choice for UV supplementation; just make sure you stick to the manufacturer-recommended hanging height, and you're good to go!

How to Provide UV Light to Indoor Cannabis Plants
  • T5

We have already mentioned T5 lights, but it's worth going over them again, if for one crucial reason. Standard T0.2 ozow lights differ slightly from the other options because of the chemical reaction that occurs within them. This reaction produces a lot of UV light, but the bulb’s phosphorous covering blocks most of it. To capture UV benefits with a T0.2 ozow light, switch out the bulb for a fluorescent glow or a full-spectrum option. Either will give plants the boost they need.

How to Provide UV Light to Indoor Cannabis Plants
External Resources:
  1. UV‐B radiation effects on photosynthesis, growth and cannabinoid production https://onlinelibrary.wiley.com
Disclaimer:
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

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Privacy Policy - Royal Queen Seeds

To ensure a safe online environment and guarantee adequate data protection, we strictly comply with all legal requirements. In this privacy statement, we provide information about how and for what purpose data is collected, safety measures, storage periods and contact details.


COMPANY NAME: SNORKEL SPAIN, SL (hereinafter ROYAL QUEEN SEEDS)

C/ Vilar d'Abdelà, 5 (nave 1) CP: 08170 de Montornès del Vallès

+34 937 379 846

support@royalqueenseeds.com


The present Privacy Policy sets out the terms on which we will treat personal data at ROYAL QUEEN SEEDS; this includes any personal data collected through our website https://www.royalqueenseeds.com/ as well as any other data we process in the course of our business activities.

ROYAL QUEEN SEEDS collects the following personal data for the purposes listed below:

SECTION 1 – PERSONAL INFORMATION WE COLLECT

1.1 Account purchases

Account purchases can only be made if you are in possession of a personal account. When you create an account or purchase something from our shop, as part of the buying and selling process we collect the following personal information that you provide to us:

This information is required for delivery. In addition, when you browse our shop, we automatically receive the Internet Protocol (IP) address of your computer. Based on this information, we can optimise your online experience and at the same time protect our online environment.

Purpose of data collection

We collect and store account-related data for the following purposes:

(a) to carry out obligations arising from any contracts between you and us, and to provide you with information, products and services that you may request from us;

(b) to set up, manage and communicate with you about your account and your orders;

(c) to conduct market research and analysis;

(d) to confirm your age and identity, and to detect and prevent fraud.

1.2 Newsletters

With your explicit permission, we may send you newsletters about our shop, new products and other updates. We send newsletters based on your explicit consent. In the event that you purchase a product, and in accordance with current regulations, we may send you commercial communications in accordance with the legitimate interest of our company, always about products or services similar to those you have purchased or contracted. In any case, you may exercise your right of opposition through the channels announced in this Privacy Policy. The following information is collected in relation to the newsletter:

We do not need to know the sex of the person in order to send the newsletter (data minimisation: by law we must ask for data that is strictly necessary to provide the service, and in this case knowing the sex is not necessary to send the newsletter).

Purpose of data collection

The data collected is used to:

(a) personalise our emails, including your name and gender;

(b) provide gender-specific content.

You can withdraw your consent at any time by using the link provided in the newsletter or the contact information provided in section 2.

1.3 Customer service and contact form

In order to provide appropriate support, our customer service employees have access to information related to the account. Consequently, their support will be highly effective and friendly. The data provided in our contact form is used by our CRM provider, SuperOffice. We will only use your details to respond to your message.

SECTION 2 – LEGITIMATE INTEREST

If you have purchased any of our products, please note that we may process your personal data for promotional purposes, based on Royal Queen Seeds' legitimate interest only to offer you products or services from our company and about products or services similar to those you have purchased. You may exercise your right to opt out of future messages by the means set out in this Privacy Policy or through any notification you receive.

2.1 How do you withdraw consent?

If you change your mind, you can withdraw your consent for us to contact you for the purpose of collecting, using, or disclosing your data at any time by reaching out to us at: support@royalqueenseeds.com.

SECTION 3 – DISCLOSURE

We may disclose your personal information if we are required to do so by law or if you breach our Terms of Service.

SECTION 4 – HOW LONG DO WE KEEP YOUR DATA?

At Royal Queen Seeds, we will not retain your data for longer than is necessary for the purposes described in this Policy. Different retention periods apply for different types of data; however, the longest period we will normally hold any personal data is 10 years.

4.1 Account information

Data relating to the account remains relevant for as long as the consumer is in possession of an account. Therefore, the data remains documented for as long as the account exists. When our customers delete an account, the associated data will be deleted within a reasonable period of time. Requests regarding the inspection or correction of stored personal data or the deletion of an account can be sent to support@royalqueenseeds.com.

4.2 Newsletters

In the event that you give us your consent to inform you about our products or services, we will keep your data until you express your wish not to receive any further communications from us. However, we regularly (every month) carry out a relevance check. Registered customers (and their personal information) will be deleted whenever customers do not reply to our request. In addition, our newsletter mailing has an opt-out feature. Consumers can withdraw their consent by using this opt-out feature.

SECTION 5 – COOKIES

Cookies are small information files that notify your computer of previous interactions with our website. These cookies are stored on your hard drive, not on our website. Essentially, when you use our website, your computer displays its cookies to us, informing our site that you have visited before. This allows our website to function more quickly and remember aspects related to your previous visits (such as your username), making your experience more convenient. At Royal Queen Seeds, we use two types of cookies: functional and analytical.

5.1 Functional Cookies

Functional cookies are used to enhance your online experience. Among other things, these cookies track what is added to your shopping cart. The use of these cookies does not require prior authorization.

5.2 Analytical Cookies

Analytical cookies are used for research and market analysis. The data collected with these analytical cookies is anonymous, making it unusable for third parties. The use of these cookies does not require prior authorization.

SECTION 5 – THIRD-PARTY SERVICES

Third-party services are required to conduct transactions and provide our services. In general, the third-party providers we use will only collect, use and disclose your information to the extent necessary to enable them to perform the services they provide to us.

However, certain third-party service providers, such as payment gateways and other payment transaction processors, have their own privacy policies regarding the information we must provide to them for your transactions.

We encourage you to read the privacy policies of these providers so that you can understand how these providers will handle your personal information.

In particular, certain suppliers may be located or have facilities located in a different jurisdiction than yours or ours. Therefore, if you choose to proceed with a transaction involving the services of a third party, your information may be subject to the laws of the jurisdiction in which that service provider or its facilities are located.

Once you leave our website or are redirected to a third-party website or application, you are no longer governed by this Privacy Policy or the Terms of Service of our website.

Web analytics service (anonymous data)

On this website we have integrated an element of a web analytics service (with anonymisation functionality). Web analytics can be defined as the gathering, processing and analysis of data about the behaviour of visitors to websites. An analytics service collects, among other things, data about which website a person came from (the so-called referrer), which sub-pages they visited or how often and for how long they visited a sub-page. Web analytics is mainly used for website optimisation and for a cost–benefit analysis of internet advertising.

Courier service

To complete deliveries we use a courier service. This courier service carries out the delivery between our company and the consumer's home. To complete these logistics, the company requires access to the consumer's name and address information.

Mailing service

Royal Queen Seeds uses a third-party mail service provider to send its newsletter. This provider has access to limited account information related to opt-in consent (e.g. email address).

Marketing services

Royal Queen Seeds has the support of a company that specialises in marketing and communication activities. Their access to personal information is very limited and mostly anonymous.

Payment services

At Royal Queen Seeds we use external payment services to handle our transactions (e.g. credit card payments).

SECTION 6 – SECURITY

To protect your personal information, we take reasonable precautions and follow industry standard best practices to ensure that it is not inappropriately lost, misused, accessed, disclosed, altered or destroyed.

If you provide us with your credit card information, the information is encrypted using secure socket layer technology (SSL) and stored using AES-256 encryption. Although no method of transmission over the internet or electronic storage is 100% secure, we follow all PCI-DSS requirements and implement additional industry standards that are commonly accepted. Information related to the account is protected with a hashing method. This method transforms the information into a generated hash. As a result, confidential information is protected and invisible, even to us. In addition, our databases are exceptionally protected against unauthorised access. For example, access to the database is only possible and permitted via approved IP addresses (e.g. from Royal Queen Seeds headquarters). Other attempts and addresses are rejected at all times.

Furthermore, data is anonymised as much as possible, so it cannot be directly linked to a specific consumer. With this data, however, we may be able to carry out market research and analysis. In addition, the third parties concerned (e.g. mailing service) are examined prior to our collaboration, comply with the GDPR from the EU and receive a processing agreement. Within Royal Queen Seeds, employees are assigned different access permissions. Specific permission provides access only to information that is strictly required to perform a task. Digital security measures are subject to change and must meet high requirements to ensure the safety of online customers. That is why, at Royal Queen Seeds, we appoint a security officer. Regular verification and improvement of security measures (where necessary) are part of the role.

SECTION 7 – CHANGES TO THIS PRIVACY POLICY

We reserve the right to modify this Privacy Policy at any time, so please check back regularly. Changes and clarifications will be effective immediately upon being published on the Website. If we make substantial changes to this policy, we will notify you here that it has been updated so you will know what information we collect, how we use it and under what circumstances, if any, we use and/or disclose it.

SECTION 8 – YOU HAVE THE RIGHT TO: