By Luke Sumpter


Generally, when we think of how plants absorb nutrients, our minds go to their root systems, while we picture the leaves as the centre of photosynthesis. While this is broadly true, it is not the whole picture. Plants can, in fact, absorb nutrients through their leaves with a very high degree of efficiency, and growers can use this to their, and their plants’, benefit.

In this article, we look at the use of foliar sprays for cannabis plants. These sprays can be used to feed plants when they lack certain nutrients, and to deliver organic pesticides directly to the leaves in case of infestation.

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Should You Foliar Spray Cannabis?

The term foliar spray is broad, and has multiple applications depending on what you want to achieve. Ultimately, the term describes a spray that is applied to the foliage of a plant—what this spray seeks to achieve is determined by what’s in the solution.

But there are two main instances in which you could benefit from using a foliar spray. One is in case of infestation; certain organic pesticides can be applied to the foliage of plants to deter or kill problematic insects.

You can also employ supplemental foliar feeding. By spraying fertiliser onto the leaves, you can deliver an easily accessible hit of nutrients that plants absorb through their stomata—the tiny pores that cover the leaves. While this can’t be used in place of feeding via the roots, it can be used in case of nutrient deficiencies, or even as a regular, light supplement.

Some g-rowers only use foliar sprays in acute circumstances; when there is an infestation or a nutrient deficiency. Others use them preventatively to avoid either of these circumstances.

Benefits of Foliar Spraying Cannabis

The benefits of foliar spraying weed are as follows:

  • Provides easily accessible nutrients in case of deficiency, and is particularly efficient in delivering magnesium, calcium, zinc, iron, and manganese.
  • Can be used to spray a range of organic, non-toxic pesticides directly onto the affected areas of plants, in case of infestation.
  • Can be used to supplement nutrients throughout the plant’s life cycle as a preventative measure.
  • A neem oil foliar spray can work preventatively against insects.
  • High concentrations of nutrients in foliar sprays do not negatively affect concentrations of nutrients in the soil, nor do they disrupt the soil biome.

When Should You Use a Cannabis Foliar Spray?

As mentioned, there are different instances in which you should/could foliar spray cannabis plants:

  • Nutrient deficiency: If you identify a nutrient deficiency, then a foliar spray is the best way to immediately get a dose of the required nutrients into your plant. Absorption rates can be as high as 95%, and results can be seen in as little as 48 hours.
  • Infestation: If you notice that your plants are playing host to insects or fungi, then a potassium soap foliar spray is an effective and safe way to deal with the problem.
  • Prevention: A foliar spray can also be used every week or two to prevent various issues. A CalMag solution can give your plants micronutrients that can sometimes be difficult to deliver via the roots. Alternatively, a neem oil solution sprayed onto the leaves will keep any pests at bay and help to protect your plants from a variety of threats.
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When Shouldn’t You Use a Foliar Spray?

Equally important to know is when not to use a foliar spray for marijuana. During the flowering period, it’s best to avoid spraying your plants, if possible. Many solutions (such as neem oil) will spoil the taste of buds, even if they can still be safely consumed. But more importantly, the excess moisture introduced with a foliar spray can greatly increase the chances of mould occurring on sensitive buds.

If you really have to use a spray during flowering, then apply it only where necessary, and be accurate. Certainly avoid spraying the flowers, and only spray the necessary fan leaves.

What Is the Best Type of Sprayer to Use?

A simple handheld misting bottle is all you need to apply a foliar spray. These are very cheap and easy to acquire. If you only use one, make sure you wash it well after each use.

Alternatively, you can use a large pump spray if you have a bigger grow. These will cover plants much more easily, but will also make a space quite wet and humid. For outdoor and large grows, they are helpful, but for small grow tents, they can make everything too damp.

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How to Foliar Spray Cannabis

In what follows, we will outline how exactly to go about foliar spraying cannabis plants.

  1. The best time for foliar spraying is either early in the morning or late in the evening. If you grow outdoors, buds getting wet can be a normal occurrence due to rainy weather. If a spray with some type of fungicide is the only way to save your precious outdoor crop from a mould infestation, use a natural, safe, and residue-free product only.
  2. Do not spray in direct sunlight. The sunlight can not only burn your plants through the “lens effect” from droplets on the leaves, but it can also degrade active substances and nutrients contained in your solution. In the evening, the plant’s pores are fully open, which allows for a quicker intake compared to during the day. If you grow indoors, the best time to spray is at the beginning or end of the dark period.
  3. Avoid spraying when it is too hot or too cold. In hot temperatures, your plant’s stomata will be almost closed, making a foliar spray much less effective. On the other hand, when it is too cold, spraying could promote fungal growth. Spraying early in the morning can be best since this allows your plants to dry during the day, reducing the risk of mould.
  4. Don’t spray when you expect bad weather. Rain can make your foliar spray a waste of time, washing away or diluting your spray solution. The same goes for strong winds. When you spray outdoors, wait for rain and stormy weather to pass. When you spray indoors, it can be a good idea to turn off ventilation for an hour or two. This allows the solution to be absorbed by the leaves without any major disturbances.
  5. Don't forget the undersides. When you spray, spray the entire plant (except the buds)—in particular the undersides of the leaves. There are at least two good reasons for this. Many pests, such as spider mites and other aphids, are often located on the leaf undersides. This is also where more of the stomata are located.
  6. Take note of the recommended nutrient strengths of your solution. Most of the time, foliar feeding requires a much lower nutrient concentration than feeding your plants via the soil. If the solution that you are spraying doesn’t specify the proper amount for foliar application, start with half the recommended dose.
  7. Test your spray first to ensure that your plants don’t get irrevocably damaged. Rather than going full-out and spraying your entire crop with an untested product you just got from the internet, perform a test on a single leaf first. Wait for a day to see whether the application causes any damage before moving forward with a full feeding regimen.
  8. Avoid spraying during flowering. Spraying the buds can be bad for a number of reasons. Depending on your spray solution, this can lead to anything from a spoilt taste to an increased chance of mouldy buds.

Foliar Feeding With Grow Boosters and Stimulants

Given the speed in which nutrients are provided to plants via foliar application, this also makes it effective for providing crops with boosters and stimulants when they need them. There are a wide range of products out there, most of which actually require foliar feeding as the method of application.

Some growers make their own foliar growth stimulators, for example by mixing liquefied aloe vera leaves with water, or by using any number of DIY foliar stimulant recipes that you can find online.

Other options include:

  • Fish oil
  • Ionic nutrients
  • Fermented fruit juice (FFJ)

Foliar Spraying With Fungicides and Insecticides

Foliar sprays are a common and effective way to treat many cannabis pests and diseases, such as mites, powdery mildew, and others. A popular substance that acts as both an immediate treatment and preventative measure is neem oil.

Neem oil has the advantage of being a natural insecticide that also has some fungicidal properties. To dissolve the oil and maximise effectiveness, cultivators use a neem oil foliar spray together with aloe vera juice and some type of emulsifier, like potassium silicate. Weekly sprays during the vegetative phase can strengthen plants and increase their resistance against pests and pathogens.

Meanwhile, a foliar spray made with potassium soap (insecticidal soap) is an excellent option to tackle an infestation of harmful insects. It is particularly effective against aphids, which are some of the most common cannabis pests. A mix of neem oil dissolved in potassium soap is doubly effective. The potassium soap gets rid of the pest on contact, and the neem oil helps to prevent future attacks while strengthening your plant’s defences.

Many other natural ingredients, from cayenne pepper to nettle, cinnamon oil, and even plain milk, can help to combat powdery mildew and other fungal pathogens naturally, without causing any harm to your plants.

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Foliar Spraying and Hydroponics

Foliar feeding can also be used in hydroponic grows, though you must be more careful with your application. Also, be aware that nutrients added to the reservoirs of hydro setups will be quickly absorbed by your plants, so a foliar spray won’t have the same effectiveness as with a soil grow.

That being said, there is still a place for both pesticide and fertiliser sprays in hydro. If you do use a spray, be careful that the solution doesn’t run down into the reservoir below, otherwise you could disrupt the nutrient balance and cause overfeeding—which would be counterproductive.

Hints and Tips for Foliar Spraying Cannabis

Foliar spraying isn’t difficult, but it must be employed properly if it’s to work and not cause other problems. The following section should tie up any loose ends in your understanding, and have you ready to use a foliar spray effectively and without detriment.

When Should You Use a Foliar Spray?
Ideally, you should use a foliar spray 1–2 hours before lights come on or the sun comes up, or just after dark (outside, your plants should be okay as long as they're not in strong, direct sunlight). The reason for this is twofold. First, the spray can evaporate before it begins to work, and second, water on the leaves acts as a lens, which can concentrate light and burn the plant’s leaves.
How Much Fertiliser Should You Add to a Foliar Spray?
For young plants, use 25% of the recommended amount of feed. For older plants, you shouldn’t require more than 50% of the suggested amount.
Don’t Rely on Foliar Sprays Alone
Foliar sprays are very effective when it comes to delivering an immediate dose of nutrients to your plants, but they can’t provide the necessary quantities for healthy growth. Foliar feeding alone is not sufficient, and it must always be combined with conventional feeding via the roots. Foliar feeding is always supplemental.
Be Aware of Leaf Burn (Phytotoxicity)
Another issue that can occur if the solution evaporates before the nutrients have been absorbed is phytotoxicity, where the unabsorbed nutrients concentrate on the leaves and burn them. As mentioned, always feed out of direct, hot light.
Spray the Underside of Leaves Too
You should spray both the top and bottom of leaves, as this will maximise absorption!
Adjust pH
As with soil, the pH of a foliar spray should be within the appropriate range. For plants growing in soil, this is 6.0–7.0. For hydro-grown plants, it’s 5.5–6.5.
How Wet Should the Plant Be?
During the veg phase, you should spray plants in their entirety, ensuring the whole canopy is moist. However, you don’t want water to collect and drip. If this happens, then it’s too wet and you risk issues associated with excess moisture, such as mould.

If spraying during the flowering phase, be more conservative and try to avoid wetting the buds.
Remove Plants From the Grow Space if Possible
If you’re growing indoors and you’re able to move your plants around, it can be very helpful to take them out of the grow space while you spray them. This will keep the general space dry and stop the humidity from getting out of control and causing all sorts of other issues.

Is Foliar Feeding Cannabis Effective?

Foliar feeding is incredibly effective, as is using foliar sprays in the quest against pests. That said, it’s important to understand the limitations of cannabis foliar feeding, and to know that it can never be used in lieu of feeding via the roots, but only as a supplement. As a supplement, though, it is highly beneficial.

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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: