How to grow marijuana from seed outdoors in the UK

Growing marijuana from seed outdoors is one of the most natural and rewarding ways to cultivate your own cannabis. Whether you’re planning a modest personal harvest or cultivating several plants in your garden, beginning from seed gives you full control over genetics, growth and final quality. It’s cost-effective, environmentally friendly and produces robust plants when done correctly.

In this complete guide, we’ll walk you through each stage of growing cannabis from seed outdoors — from choosing the right seeds and preparing your soil, to germinating, transplanting, caring for your plants and harvesting. With top-tier genetics from Mavericks Genetics, you’ll be set up for a successful, healthy outdoor grow.

Why grow marijuana outdoors?

Growing cannabis outdoors offers several unique benefits:

Natural sunlight: Cannabis thrives under full-spectrum sunlight, which is difficult to replicate indoors.
Higher yields: Outdoor plants often grow larger and produce more buds per plant.
Lower costs: There’s no need for artificial lighting, grow tents or ventilation systems.
Eco-conscious: Reduced energy usage and a more natural growth cycle.

Of course, outdoor cultivation also means working with nature — weather, pests and seasonal light cycles — but with good planning, these can be easily managed.

What you need to grow cannabis from seed outdoors

Before you begin, ensure you have:

Feminised or autoflower seeds from Mavericks Genetics
Germination tools (paper towel or soil method)
Nutrient-rich soil
Compost or organic amendments
Grow containers (if not planting directly into the ground)
Basic gardening tools
Access to fresh water
A spot with 6–8 hours of daily sunlight

Tip: Choose strains suitable for your local climate. Autoflowers or fast-flowering photoperiod strains are ideal for the UK’s shorter growing seasons.

Step 1: Choose the right seeds

Genetics are the foundation of your grow. For outdoor growing in the UK, select strains that are:

Resistant to mould and pests
Capable of handling cooler temperatures
Fast-flowering to avoid early autumn rain
Photoperiod strains for maximum yield
Autoflower strains for quick harvests

Explore the full range of outdoor-ready strains at Mavericks Genetics — all rigorously tested for performance and reliability.

Step 2: Germinate your marijuana seeds

Start indoors by germinating your seeds in a controlled environment.

Recommended method: Paper towel technique

Dampen two clean paper towels with filtered water
Place the seed between them
Store in a dark, warm place (~24°C)
Check daily for the emergence of the taproot (usually 1–5 days)
Transplant once the root reaches 0.5–1.5 cm

Step 3: Prepare your outdoor grow site

Soil preparation

Healthy soil is vital. You can plant directly in the earth or use pots.

Ideal soil characteristics:

Loamy texture (balanced clay, sand and organic matter)
pH between 6.0 and 7.0
Enriched with compost or organic inputs such as worm castings or bat guano

Preparation tips:

Dig holes 30–45 cm deep and wide
Mix in perlite, compost and coco coir to improve drainage and aeration
Let the soil rest for a week if amending it

Sunlight and airflow

Choose a site with:

6–10 hours of direct sunlight per day
Good airflow to prevent mildew

Optional enhancements:

Windbreaks (fences, bushes)
Raised beds for improved drainage
Trellising or support cages for large plants

Step 4: Transplant seedlings outdoors

Once your seedlings have developed 2–3 sets of true leaves, they’re ready for outdoor life.

How to transplant:

Acclimate them by gradually increasing sunlight exposure over 3–5 days
Transplant during early morning or late afternoon to reduce stress
Water immediately and apply mulch to retain moisture

Best time to transplant:

After the final frost of spring
When night temperatures remain above 13°C

Step 5: Watering and feeding your cannabis plants

Watering tips

Water thoroughly but less frequently. Let the top few centimetres of soil dry out between waterings.

General guide:

Every 2–3 days during early vegetative growth
Daily during peak summer heat

Use mulch to maintain soil moisture and deter weeds.

Nutrient needs

Use organic fertilisers or compost teas. Nutrient requirements vary:

Vegetative stage: High nitrogen, moderate phosphorus and potassium
Flowering stage: Low nitrogen, high phosphorus and potassium

Note: Stay tuned for our full guide on cannabis nutrient schedules.

Step 6: Preventing pests and disease

Outdoor plants are more exposed to nature’s challenges, so early prevention is essential.

Common threats:

Aphids, spider mites, caterpillars
Powdery mildew, bud rot
Slugs and root pests

Preventative measures:

Apply neem oil or BT spray weekly
Use companion plants like garlic, basil or marigold
Clear the surrounding area of weeds and debris
Check under leaves daily for signs of trouble

Step 7: Training and pruning techniques

Help your plants thrive with proper training and pruning:

Low stress training (LST)

Gently bend and tie down stems to spread out the canopy
Increases light exposure and promotes bushier growth

Topping or FIMing

Cut the top of the main stem to encourage multiple colas
Do this when plants have 5–6 nodes

Pruning

Remove inner growth that doesn’t receive light
Improves airflow and reduces risk of mould

Step 8: Flowering stage and when to harvest

When do outdoor plants flower?

Photoperiod strains: Begin flowering when daylight falls below 14 hours (late summer)
Autoflower strains: Flower automatically after 3–5 weeks

Signs it’s time to harvest:

Pistils turn from white to orange/brown
Trichomes become cloudy or amber (view with a magnifying glass)
Fan leaves begin to yellow naturally

Step 9: Harvest and dry your cannabis

Harvesting process:

Cut branches in the early morning
Trim large fan leaves
Hang upside down in a dark, well-ventilated area (16–21°C, 50–60% humidity)
Dry for 7–14 days until stems snap
Cure buds in airtight jars for 2–4 weeks, “burping” daily

Best strains to grow outdoors from seed

Some strains are especially well-suited to outdoor growing in the UK:

Autoflowers for multiple harvests in one season
Mould-resistant photoperiod strains for wetter regions
High-yield hybrids for full sun

Explore Mavericks Genetics to find outdoor strains perfect for your conditions and preferences.

Final thoughts: Growing marijuana outdoors from seed is natural and powerful

Outdoor cannabis cultivation from seed is a deeply satisfying process that connects you with nature and your plants. With careful planning, preparation and patience, you can produce aromatic, resin-rich buds using only sunlight and soil.

Whether you’re starting small or planting a full garden, begin with premium genetics from Mavericks Genetics to maximise your grow’s potential.

Ready to grow outdoors?

Visit Mavericks Genetics and browse our complete collection of outdoor-ready cannabis seeds. Each pack is backed by strong genetics, excellent germination rates and breeder-grade performance.