By Luke Sumpter

A complete month-by-month guide to growing cannabis outdoors in the UK.


Growing outdoors comes with a unique set of challenges per location. Everything needs to be considered, from local pest species to the best strain for the job. Simply follow the growing guide below to boost your chances of a successful outdoor harvest in the UK.

GROWING CANNABIS OUTDOORS IN THE UK IN 2025

Growing cannabis outdoors in the UK usually involves (at least) one consistent weather condition: rain! Your plants will rarely go thirsty or wilt from the heat. The UK experiences a temperate climate defined by cool, wet winters and warm, wet summers. The country rarely experiences extreme weather events, although flooding and droughts do occur from time to time. The UK sees an average of 133 days of rain and around 1,350 hours of sun per year. This fine balance of rain and sun gives plants plenty of the key resources to develop properly.

The UK features four climate segments:

South-east: This region experiences cold, biting winters along with warm, dry, and pleasant summers. Continental winds keep things relatively dry in general. South-east UK encompasses London, Brighton, Cambridge, and Norwich.

South-west: This area of the country sees mild and very rainy winters contrasted by warm and wet summers. Tropical winds from the south extend the growing season. Includes Cornwall, Devon, Bristol, and Cardiff.

North-west: The north-west experiences mild winters and cool summers. Maritime winds bring a whole load of rain all year round. This region covers Northern Ireland, northern Wales, and western Scotland.

North-east: Arctic winds from the north bring cold winters, cool summers, steady rain, and a shorter growing season. Includes Newcastle, York, Edinburgh, and Aberdeen.

GROWING CANNABIS NETHERLANDS

Unfortunately, the United Kingdom is lagging behind more progressive European nations when it comes to cannabis legislation. The government categorises cannabis as a class B substance, meaning mere possession can lead to a maximum 5-year prison sentence, an unlimited fine, or both. Growing and supplying cannabis can lead to the more extreme punishments of up to 14 years in prison, an unlimited fine, or both.

Despite the draconian nature of UK cannabis laws, things are improving. CBD products are widely available over the counter in shops, so long as they possess no more than 0.2% THC. The government also allowed doctors to start prescribing cannabis products to patients in 2018. In 2019, the NHS received the all-clear to start prescribing cannabis-based products for Lennox–Gastaut syndrome and Dravet syndrome.

The UK has a long way to go to match the more relaxed approaches of certain American states and European nations.

A GUIDE ON GROWING CANNABIS OUTDOORS IN THE UK

Below, we’ll generalise and focus on the south-east, south-west, north-east, and north-west, while touching on specific locations along the way. It’ll help if you do a little more research on your specific area just to make sure you have all the bases covered.

MARCH

Day length March 1st: 10h 57m
AVG temperature: 3–10°C

March marks the official start of spring. However, things are still pretty chilly in most of the country. But this doesn’t mean growers can’t get a head start indoors. Start germinating your seeds and placing emerging seedlings under LED lights or on a sunny windowsill.

Start weeding your beds and dressing them with high-quality compost. Layer them with straw or wood chip mulch to trap moisture and prevent weeds from returning. If you’re growing in containers, dress them with good compost, too. Start cleaning out and preparing your polytunnel or greenhouse, if you’re lucky enough to have one. Scrub down any algae from the glass panels, brush out debris, and get it ready to host your cannabis plants in the coming weeks.

Certain microclimates around the UK allow lucky growers to plant outside during March. Cultivators in the Scilly Isles, Anglesey and Dungeness usually see the last frost around late February.. Pay close attention to the forecast and decide whether the risk might pay off. Make sure to keep a backup crop growing indoors just in case.

How To Grow Cannabis Outdoors - UK

APRIL

Day length April 1st: 12h 59m
AVG temperature: 5–13°C

April brings a significant improvement in weather and sunlight. Bluebells, wild garlic, and other aromatic spring flowers lead the charge of emerging plant life. Although April brings a nice, warm heat, frost still poses a significant risk. Growers in most regions will need to keep their plants indoors under lights and on windowsills for a couple more weeks to be safe. However, cultivators with greenhouses or polytunnels will be able to safely move their plants to these structures during April.

Only water your seedlings when the top inch of soil dries out, being careful not to overwater. Head out into the garden and keep the "bad weeds" under control. You’ll be able to sow hardy companion plants during April, such as peppermint, yarrow, coriander, and marigold. These plants will start flowering in the coming months, helping to distract pest insects and attract beneficial ones. Take a stroll around your beds, look out for weeds, and remove them by hand if you stumble across any.

How To Grow Cannabis Outdoors - UK

MAY

Day length May 1st: 14h 53m
AVG temperature: 8–16°C

The coastal regions will see their final frost at the start of May. However, more central areas—the East and West Midlands—and Northern Scotland will have to hold back until the middle of the month. If you choose to move your plants outdoors, containers will be the best option. They’ll allow you to move your plants indoors or into your greenhouse if you suspect a sub-zero night.

Growers in the south-east and south-west should make sure their greenhouses and polytunnels are well-ventilated. Occasional heat waves will greatly increase the temperature in these structures, to the degree that it might harm your plants.

Transplant your seedlings into containers or beds filled with organic, living compost. This contains microorganisms that will help your plants thrive. Consider adding mycorrhizal fungi to your growing medium for root system support and enhanced nutrient uptake.

After planting out, water in your plants and keep them well-hydrated throughout the month. The north-west, north-east, and Northern Scotland receive heavy rain during May. If things get to be too much, erect a tarp over the beds or move containers indoors to prevent overwatering. Growers in the south-east and south-west will see less rainfall and should begin setting up drip irrigation systems or hand watering to keep up with demand.

Dress your beds and containers with compost and worm castings to provide slow-release nutrients throughout the vegetative phase. Use compost tea or seaweed fertiliser to make sure your plants get all the minerals they need. Alternatively, mix your soil with Easy Boost Organic Nutrition and water plants with Easy Grow Booster Tablets to provide the necessary nutrients with minimal fuss. Follow the instructions on your chosen products to prevent overfeeding and nutrient burn.

Start sowing more delicate companion plants, such as chamomile, to help stave off pests later in the growing season. Set up fences and netting if your area experiences a lot of deer and other browsing mammals.

How To Grow Cannabis Outdoors - UK

JUNE

Day length June 1st: 16h 20m
AVG temperature: 11–19°C

Summer officially arrives! June sees temperatures boom and daylight hours greatly increase. The risk of frost will have passed in all regions, except certain areas of the Scottish Highlands. Vegetating cannabis plants take advantage of this and start packing on some serious mass—increasing their demand for water and nutrients. The south-east and north-east typically see a drop in rainfall during June. Make sure your irrigation systems are running correctly, and be sure to water plants in the morning or evening for best results.

Keep an eye out for persistent weeds and remove them on sight to prevent them from pulling nutrients from the soil. Layer down more mulch as the older material begins to break down to reinforce these natural weed barriers.

Your increasingly mature plants will be resilient enough to undergo training techniques. Employ methods such as low-stress training (LST) to keep plants low to the ground, making it an optimal choice for discreet UK growers.

How To Grow Cannabis Outdoors - UK

JULY

Day length July 1st: 16h 33m
AVG temperature: 13–22°C

July ushers in the peak of summer, the hottest temperatures, and longest days of the year. Your vegging plants will continue to surge in size, put out new fan leaves, and burrow their roots deep into the Earth. Growers in the north-west will receive around 100–300mm of rainfall during July—enough to keep watering at a minimum. However, rainfall will become scarce in the rest of the country. Keep up with watering—especially in greenhouses—and don’t let your plants dry out.

Dedicate time in the morning to take a meditative walk around your crop. Inspect fan leaves for signs of nutrient deficiencies. These signs usually manifest as yellowing leaves, dropping leaves, and curled leaf tips. Learn how to identify and remedy deficiencies here.

You’ll also want to keep an eye out for common cannabis pest species such as whiteflies and aphids. Remove any by hand if the numbers are low. If they start to multiply, employ biological control methods such as introducing beneficial insect species.

Continue training your plants, aiming to keep the canopy as even as possible to provide future flowers with optimal light exposure. Make some final adjustments towards the end of July, as training during the flowering stage will be detrimental to growth.

How To Grow Cannabis Outdoors - UK

AUGUST

Day length August 1st: 15h 23m
AVG temperature: 13–21°C

The final month of summer has arrived. Both temperature and daylight hours begin to dip. Cannabis plants pick up on the reduction of available light, which triggers them to begin flowering.

Flowering plants require lower levels of nitrogen and higher levels of phosphorus and potassium. You’ll need to change your feeding regimen to cater to these demands. Top-dress your soil with worm castings, kelp meal, and bone meal for a slow-release formula. Water regularly with Easy Bloom Booster Tablets to provide adequate levels of potassium, calcium, and magnesium.

Humidity can become an issue as flowers start to develop. Their resinous and compact nature makes them an ideal breeding ground for mould. All of the UK can hit humidity highs of around 90% during August. Water the ground around your plants and don’t spray your flowers directly. Keep polytunnels and greenhouses extremely well-ventilated.

Defoliation serves as a great weapon in the battle against mould. The technique involves cutting away several fan leaves to improve airflow through the canopy. Defoliation also works well to allow more light to reach bud sites deeper in the canopy.

How To Grow Cannabis Outdoors - UK

SEPTEMBER

Day length September 1st: 13h 32m
AVG temperature: 11–18°C

Temperature and daylight hours continue to drop. Your flowers will start edging towards maturity. Scents of aromatic terpenes will fill your garden. Although pleasant, the smell can attract unwanted pests. Thankfully, the companion plants you sowed earlier in the season will help to minimise any damage. You can even start harvesting species such as chamomile and lavender to craft relaxing teas.

Fast-flowering indica strains will be nudging closer to maturity. Flush your plants with pure water two weeks before harvest. Proceed to harvest, dry, and cure your bounty.

The south-east and north-east experience little rainfall throughout September. Keep up with hand watering and carry out routine checks on your irrigation system to ensure everything is running smoothly. The south-west and north-west will see between 100–500mm of rain come through. Allow nature to water your plants, but keep a tarp on handy in case severe and prolonged rainfall occurs.

How To Grow Cannabis Outdoors - UK

OCTOBER

Day length October 1st: 11h 36m
AVG temperature: 8–14°C

In October, the leaves start dropping from the trees, and temperatures become noticeably colder. Autumn has arrived, winter waits around the corner, and the growing season comes to a close.

Now, turn your attention to longer-flowering sativa cultivars. Keep them well-fed, watered, and ventilated. Keep up with defoliation as new fan leaves begin to develop. Most of the country will start to experience a good amount of rainfall during October. However, cultivators in Northern Ireland and several locations in the north-west and south-west will need to continue manual watering.

Growers in central Scotland, central England, and south of London will need to be vigilant of the first frost setting in before harvest. Inspect your mature flowers for mould and consult our mould guide if you spot anything unsightly.

Harvest, trim, and dry your plants. Now it’s time to kick back, relax, and enjoy the fruits of your labour!

How To Grow Cannabis Outdoors - UK

PROS AND CONS OF GROWING CANNABIS OUTDOORS IN THE UK

Sure, the sheer amount of rain can be annoying, but it keeps plants healthy and luscious when dealt with correctly!

Pros:

• Plenty of rain
• Mostly dry during the late flowering stage
• Growers know to expect occasional bad weather, which keeps them prepared with tarps, fans, and other equipment

Cons:

• Excess rain can lead to root rot and bud rot
• Draconian laws make growing cannabis a discreet activity

Check out three of the best strains to grow in the UK below.

Northern Light — Grow her anywhere in the UK

Known all over the world for her impressive genetics, Northern Light can easily handle the often wet and humid conditions of the UK summer. This pure indica strain delivers a soothing body high fuelled by a THC level of 18%. Her fruity can spicy terpenes make the high even more enjoyable. Prepare to harvest a rewarding yield of 575–625g/plant after a flowering time of 7–8 weeks.

Northern Lights

Northern Light

Northern Light

Genetic background Northern Light S1
Yield indoor 500 - 550 gr/m2
Height indoor 100 - 160 cm
Flowering time 7 - 8 weeks
THC strength THC: 18% (aprox.) / CBD: Medium
Blend 0% Sativa, 100% Indica, 0% Ruderalis
Yield outdoor 575 - 625 g/per plant (dried)
Height outdoor 180 - 220 cm
Harvest time Late September
Effect A combination of stoned + high
 

Buy Northern Light

Haze Berry — For south-west growers

Those in the warmer south-west can enjoy growing longer-flowering sativa varieties. Haze Berry provides a stimulating cerebral high, berry-flavoured terpenes, and a rewarding yield. She’ll pump out up to 650g/plant after a flowering time of 9–11 weeks when grown in containers or garden beds.

Haze Berry

Haze Berry

Haze Berry

Genetic background Blueberry x Shining Silver Haze
Yield indoor 525 - 575 gr/m2
Height indoor 60 - 100 cm
Flowering time 60 - 100 weeks
THC strength THC: 20% (aprox.) / CBD: Low
Blend 80% Sativa, 20% Indica, 0% Ruderalis
Yield outdoor 600 - 650 g/per plant (dried)
Height outdoor 160 - 180 cm
Harvest time Finals d‘octubre
Effect Extremely stoned long-lasting & body relaxing
 

Buy Haze Berry

 

Critical — For northern growers

Not every grower in the UK enjoys such seasonal warmth as the south-west. Those up in Northern Scotland and the Highlands need something that can handle a shorter growing season and cold snaps—a strain like Critical. This descendant of Afghani and Skunk provides a well-balanced high that wakes up the mind while relaxing the body. Her bushy indica morphology and hardy genetics can handle the cold with ease. Enjoy a yield of 600–650g/plant after a brief flowering period of 7–9 weeks.

Critical

Critical

Critical Royal Queen Seeds

Genetic background Afghani x Skunk
Yield indoor 500 - 550 g/m2
Height indoor 80 - 140 cm
Flowering time 7 - 8 weeks
THC strength THC: 18% (aprox.) / CBD: Low
Blend 40% Sativa, 60% Indica
Yield outdoor 500 - 550 g/per plant (dried)
Height outdoor 180 - 220 cm
Harvest time Late September
Effect Stoned, physically and mentally
 

Buy Critical

YOU TOO CAN GROW CANNABIS OUTDOORS IN THE UK

Many cannabis cultivars thrive in the UK, providing growers with satisfying yields year after year. Frequent rainfall keeps plants hydrated and luscious—just keep a makeshift shelter handy in case of non-stop precipitation. Certain areas experience a shorter growing season, so erecting a cheap polytunnel can help growers extend the season and cultivate sativas with fewer hurdles. Growing in the UK comes with a few challenges, but none that can't be risen to; you just need to start the season prepared and ready to act.

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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: