By Luke Sumpter Reviewed by: Silvia Maroto


Coffee. Second only to water, this caffeinated beverage ranks as the most consumed drink in the world; around 400 billion cups[1]are consumed each year. You know coffee as a brown powder or bean that makes your mornings easier to endure. However, the plant itself has a rich history and originates in the ancient coffee forests on the Ethiopian plateau.

Away from its role as an energising drink, coffee beans also contain key nutrients that plants require to survive and thrive. While most used coffee grounds face an undignified destiny of ending up in the bin, mindful gardeners give them a new lease on life. Coffee grounds serve as a superb addition to any compost bin; worms and fungi eat them and cycle nutrients into the soil food web, and they even help to deter pests when applied as a top dressing.

So, stop throwing away this valuable resource and use it to enhance the biodiversity and fertility in your cannabis garden or grow room. Below, you’ll find out the key benefits of using coffee grounds to boost plant vitality.

What Are Coffee Grounds?

Coffee grounds are the result of brewing coffee—real coffee. Whereas instant coffee granules dissolve into water and leave no trace (besides the brown stains on the inside of your mug), coffee grounds linger as the final byproduct of the coffee brewing process. There are many ways to grow cannabis plants, and there are many ways to brew a fresh cup of coffee!

Many consumers choose to purchase pre-ground coffee to skip the hassle of grinding beans. These products are either placed in a French press or inserted into a coffee filter to create cups of delicious, piping hot bean juice.

Those consumers more dedicated to the cause—self-proclaimed coffee connoisseurs—start the process from the very beginning. They load roasted beans into electric grinders (or even hand-held grinders, but only if they ride a fixed-gear bike) before brewing to achieve the freshest cup possible.

Whatever method you choose to make coffee (with the exception of instant granules), you’ll end up with used coffee grounds. Put them aside, and, over a period of a month or two, you’ll have a significant amount at your disposal.

Are Coffee Grounds Good for Cannabis Plants?

Yes! Coffee grounds are packed with important nutrients that cannabis plants require. These include:

  • Potassium: plays a role in the movement of water and nutrients throughout plant tissue
  • Phosphorous: helps to promote early root development, stalk and stem strength, and flower formation
  • Calcium: plays a key structural role in cell walls and membranes
  • Magnesium: forms the core of the chlorophyll molecule—the plant pigment that absorbs sunlight

However, applying coffee grounds to your soil doesn’t make these nutrients readily available to weed plants—which works in the organic gardener's favour. After application, different species of fungi and bacteria will start to break down the structural components of coffee grounds, including proteins and carbohydrates, as food sources.

After immobilising nutrients such as nitrogen and potassium, they’ll hold onto these substances until they die naturally or are eaten by other soil food web members, such as nematodes and protozoa. At this point, these valuable nutrients will enter the rhizosphere where plants can access them.

Therefore, coffee grounds don’t just provide cannabis plants with nutrients, but they help to sustain communities of soil microbes responsible for nutrient cycling within organic systems. Earthworms—another trusted garden ally—will also grab coffee grounds and drag them below the surface, helping to improve soil structure and water-holding capacity.

How to Use Coffee Grounds as an All-Natural Cannabis Fertiliser
  • Do Coffee Grounds Boost Acidity?

If you already grow cannabis, you’ll know that these plants favour a slightly acidic growing medium with a pH range of around 6–7 in soil. In the event that the medium becomes more alkaline, several issues can occur, including reduced nutrient absorption. Organic cannabis growers are keen to find ways to prevent this from happening; do coffee grounds work as a solution?

Unfortunately, we don’t recommend relying on coffee grounds to keep your growing medium sufficiently acidic. At best, coffee grounds are only mildly acidic, and some research[2] has found an alkaline pH in compost made from coffee grounds; the acids[3] in coffee are water-soluble, so most of them are lost during the brewing process.

  • Excellent for Compost

Coffee grounds make a great addition to the compost pile. First, they’re a frequent waste product of most households, and nowadays you can also collect used grounds from many cafes at no charge.

Second, although they appear brown, they are technically a form of “green” compost, meaning they’re an excellent source of nitrogen. Coffee grounds slowly break down and contribute to the organic matter in the soil, helping to form soil aggregates, boost aeration, hold onto water, and ramp up cation exchange capacity.

Composted coffee grounds outperform those applied immediately to the soil. Fresh coffee grounds are phytotoxic to some plant species and may reduce growth and germination rates. Following composting, they're associated with healthy growth and the increased production of desirable secondary metabolites.

  • Help to Deter Pests

Very little research exists to show that coffee grounds help to deter garden pests. However, many growers use a top dressing of coffee grounds to protect their plants every season. Anecdotally, coffee grounds help to deter some of the most voracious cannabis pests, including slugs and snails.

Gardeners speculate that the texture of coffee grounds and the remaining caffeine inside of them send hungry pest species packing. Coffee grounds also attract non-pathogenic species of Pseudomonas, Fusarium, and Trichoderma that help to fight off pathogenic fungi in the soil.

  • Enhance Soil Biodiversity

You can compare the soil microbiome to that of the human stomach. A healthy diversity of microbial species creates a harmonious balance in which different kinds of bacteria, fungi, viruses, and protozoans thrive. However, without the right inputs, members of the microbiome start to wane, giving other life forms a foothold. Eventually, these life forms become so prolific that they cause dysbiosis—a state of imbalance—and subsequent health issues.

The same applies to the soil food web. Organic gardeners strive to enhance the diversity of their pots and beds through inputs such as mulch, compost, soil drenches, and top dressings. These materials help to sustain a diverse microbial population that fuels nutrient cycling and suppresses pathogens.

Coffee grounds serve as a cheap and easily accessible organic material that will help to feed your herd of microbes.

How to Use Coffee Grounds in Your Cannabis Garden

Now you know all about the benefits of coffee grounds for marijuana plants. But how exactly should you go about using them? Which coffee grounds are best? And how long do they last in the soil?

  • Which Coffee Grounds Are Best for Weed Plants?

You don’t need to waste time or money trying to find the most elite coffee varieties. Most coffee grounds make excellent additions to the compost bin and garden. However, if possible, try to find organic coffee. Coffee plants are farmed intensively all over the world, and farmers often don’t hesitate to douse their crops with pesticides and herbicides when weeds and insects strike. These residues can end up on and around plants, where they can harm beneficial soil microbes.

How to Use Coffee Grounds as an All-Natural Cannabis Fertiliser
  • How Long Do Coffee Grounds Last?

Hungry microbes make relatively quick work of coffee grounds, as far as decomposition speed goes. Left on the ground as mulch, fungi, bacteria, and worms will break them down and work them into the soil within several months. However, you can speed things up dramatically by adding coffee grounds to hot compost piles. The thermophilic environment created through the metabolic activity of bacteria will render raw material into fresh compost within a matter of weeks.

Coffee Grounds for Cannabis Plants: A Welcome Addition to Your Garden

Now that you’re aware of the many benefits of coffee grounds for cannabis, we’re sure you’ll start saving them after your morning brew. Although fairly uninteresting to the naked eye, these brown particles are packed with important plant nutrients. Not only that, but they’re a fantastic source of food for soil microbes, worms, and other members of the soil food web.

Just remember, don’t place coffee grounds around young plants or into the growing medium during germination. Add them later on in the growing process, ideally after accelerating their decomposition in a compost pile.

External Resources:
Disclaimer:
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

Cookies settings

We are requesting your permission to use your data for the reasons stated below:

Functional cookies

Functional cookies help our website to function optimally and allow us to personalise certain features.

Preference cookies

Preference cookies allow us to remember information that influences the way our website looks, including your preferred language based on your region.

Analytical cookies

Analytical cookies give us insights into website traffic and customer behaviour, including how many people visit our site, how long they browse for, and which parts of our site they visit.

What are cookies?

Cookies are small pieces of data from a particular website that get stored on a user’s computer while they’re surfing the internet. Cookies have several different functions. Some of them track browser activity that enables businesses to deliver targeted advertisements. Other cookies serve to remember user login details to different websites to make jumping on social media, or other sites, a more fluid process. Because each cookie has its own unique ID, these pieces of data allow website owners to measure the unique traffic coming into their site.

Why do we use cookies?

Cookies come in handy when you visit our website. They ensure you stay logged in, that you can shop safely, and that the items you add to your cart stay there before you make a purchase. But cookies also help us. The data they provide allow us to improve our website and enable us to present you with targeted advertisements that are compatible with your interests.

What kind of cookies do we use?

Functional cookies

Functional cookies help our website to function optimally and allow us to personalise certain features.

Preference cookies

Preference cookies allow us to remember information that influences the way our website looks, including your preferred language based on your region.

Analytical cookies

Analytical cookies give us insights into website traffic and customer behaviour, including how many people visit our site, how long they browse for, and which parts of our site they visit.

How can I disable or delete cookies?

Not a fan of cookies? No worries. You can disable them (with the exception of necessary cookies) in your browser settings. However, blocking cookies may impact your browsing experience and prevent you from enjoying all of the technical features of our site.

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: