How long from seed to harvest cannabis takes

When planning your first grow, one of the most common questions is: how long does it take to grow cannabis from seed to harvest? The answer depends on several key factors—particularly the type of strain you’re cultivating and your chosen growing method.

This guide outlines the full cannabis cultivation timeline from seed to harvest. Whether you're working with autoflower seeds or photoperiod strains, growing indoors or outdoors in the United Kingdom, you’ll find everything you need to plan and carry out a successful grow.

At Mavericks Genetics, we offer premium cannabis seeds bred for fast germination, vigorous growth and excellent yields. Let’s explore how long the journey from seed to harvest really takes.

Average time from seed to harvest: quick summary

These timeframes include germination, seedling, vegetative and flowering stages, but exclude post-harvest drying and curing.

Full cannabis growth timeline from seed to harvest

Let’s break down each phase of the cannabis lifecycle and how long each stage takes to complete.

1. Germination (1–7 days)

Cannabis seeds usually take 1 to 5 days to germinate using the paper towel or soaking method, though older seeds can take up to a week.

Read more in our article: How long do cannabis seeds take to germinate

2. Seedling stage (1–2 weeks)

Once the seed sprouts, it enters the seedling phase, beginning to grow its first true leaves and a stable root system.

• Duration: 7–14 days

• Light: 18–24 hours per day

• Best in: Small pots or starter plugs

This stage requires soft lighting and light but consistent watering.

3. Vegetative stage (2–8 weeks)

During this phase, cannabis plants develop their full structure—stems, fan leaves and branches.

• Autoflowers: 2–4 weeks in veg before flowering automatically

• Photoperiods: Typically 4–8 weeks, but can be extended based on grower goals

Indoor growers maintain an 18/6 light cycle, while outdoor plants remain in veg until summer days begin to shorten.

4. Flowering stage (6–12 weeks)

This is when the plant begins producing buds. Flowering is triggered by:

• Autoflowers: Automatic flowering after 2–4 weeks

• Photoperiods: Change to 12/12 light indoors or natural light cycle outdoors

Flowering duration by strain:

During this phase, switch to bloom nutrients, stabilise humidity and maintain consistent lighting.

Total time from seed to harvest by grow type

Autoflower strains: 8–12 weeks

Autoflower cannabis seeds are excellent for quick grows. Most go from seed to harvest in 70 to 90 days.

• Week 1–2: Germination and seedling

• Week 3–5: Vegetative growth

• Week 6–10: Flowering

• Week 10–12: Harvest, drying and curing

Perfect for small spaces or short UK grow seasons. Explore autoflower seeds from Mavericks Genetics for premium fast-finishing options.

Photoperiod indoor grows: 12–20 weeks

Indoor photoperiod grows offer more control over plant size and flowering onset.

• Week 1–2: Germination and seedling

• Week 3–8: Vegetative stage (can be adjusted as needed)

• Week 9–16: Flowering stage

• Week 17–20: Harvest, drying and curing

Though they take longer, photoperiod grows often produce higher yields.

Photoperiod outdoor grows: 4–6 months

Outdoor cannabis grows in the UK follow a seasonal calendar. Typically, seeds are started in spring and harvested in early autumn.

• Germination: Early spring

• Vegetative growth: Late spring to midsummer

• Flowering: Midsummer to early autumn

• Harvest: September to October, depending on strain and climate

Choose genetics suitable for your region for best results.

How to speed up your grow

If you want to shorten the time from seed to harvest, try the following:

• Choose autoflowers: They flower automatically and grow quickly

• Use fast-flowering photoperiods: Some indica strains finish in 6–8 weeks

• Start indoors: Even for outdoor grows, this gives your plants a head start

• Optimise the environment: Keep light, temperature and humidity stable

• Grow hydroponically: Roots grow faster than in soil

Want faster harvests? Browse our quick-harvest seeds now.

Don’t forget drying and curing (2–4 weeks post-harvest)

After harvest, buds must be dried and cured properly to preserve quality.

Drying: 7–14 days

• Hang buds in a dark, well-ventilated area

• Maintain 16–21°C and 45–55% humidity

• Buds should snap cleanly off stems when ready

Curing: 2–4 weeks

• Place buds in airtight glass jars

• Open (burp) jars daily for the first week

• Enhances smoothness, aroma and cannabinoid profile

Though not part of the “seed to harvest” grow period, curing is essential for a premium finish.

Common factors that delay harvest time

• Poor seed quality: Use stable, tested genetics from Mavericks Genetics

• Environmental stress: Heat, cold, pests or overwatering can stunt growth

• Light leaks: Can confuse photoperiod strains and disrupt flowering

• Nutrient imbalances: Deficiencies or excesses delay development

• Transplant shock: Handle plants with care when repotting

Observing your plants daily and correcting issues early helps keep your timeline on track.

Final timeline summary

Know your grow timeline

Understanding how long it takes to grow cannabis from seed to harvest helps you plan, avoid surprises and maximise yields. Whether you're growing autoflowers for speed or photoperiods for control, grow time ranges from 8 weeks to 6 months depending on method.

If you're ready to begin or planning your next grow, start with top-tier seeds bred for performance and reliability.

Get growing today with Mavericks Genetics—your trusted UK source for feminised, autoflower and fast-flowering cannabis seeds.