When Should I Start My Cannabis Seeds for the Summer? (Quebec Grower Timeline)

If you’re growing outdoors in Quebec, timing is everything. Start too early and cold nights can stunt seedlings or kill them. Start too late and photoperiod plants may not finish before fall weather rolls in. This guide shows you when to start cannabis seeds for summer based on Quebec’s short season, with clear timelines for photoperiod feminized seeds and autoflower seeds, plus tips for hardening off, transplant timing, and strain selection.

Quick note: Quebec’s last spring frost date varies by region. Around the Montréal area, many frost-date sources place the average last frost in early-to-mid May (but always use your local forecast). Use the schedule below as a framework, then adjust to your town’s conditions.

The Simple Answer (Most Quebec Growers)

• Photoperiod (feminized) seeds: start indoors late March to late April (about 4–8 weeks before transplant).
• Transplant outdoors: usually mid-May to early June once frost risk is gone and nights are consistently mild.
• Autoflower seeds: start late May to late June outdoors (or indoors 2–3 weeks earlier if you want a head start).

If you’re new to seeds and want a full walkthrough from sprout to harvest, start here: How To Grow Cannabis From Seeds.

Step 1: Find Your Local “Safe Planting Window” (Last Frost + Night Temps)

For outdoor cannabis in Quebec, the true “go-time” is not a calendar date—it’s a combination of:

• Last frost risk in your area
• Soil temperature warming up
• Night temperatures staying consistently comfortable (cold nights can stall growth)

Two frost-date references many gardeners use provide averages for Québec locations (for example, Montréal often shows early-to-mid May ranges depending on the dataset). Use these as a baseline, then confirm with your local weather forecast before you transplant:

• Average frost dates for Montréal and QC towns: Montreal Frost Dates (Almanac)
• Last frost ranges for Quebec locations (example: Montréal often listed in mid-May ranges): Quebec Average Last Frost Map

Step 2: Choose Your Schedule (Photoperiod vs Autoflower)

Photoperiod feminized seeds (best for bigger summer plants)

Photoperiod plants veg all summer and start flowering as days shorten later in the season. In Quebec, timing matters because late-season humidity and cooler nights can hit before some long-flowering genetics finish.

Best indoor start window for most of southern Quebec:

• Standard hybrids/indica-leaners: start indoors early-to-mid April
• Long-flowering sativa-leaners: start indoors mid-to-late March (earlier start helps them finish)

Want bigger outdoor yields? Use this guide: How To Get Big Cannabis Yields Outdoors.

Autoflower seeds (best for short summers and fast harvests)

Autoflowers are triggered by age, not daylight, so they’re a great fit for Quebec’s shorter season. Many autos finish in roughly 8–12 weeks, making them ideal for a summer run (and sometimes even multiple runs in one season depending on weather).

Learn the basics here: What Are Autoflowering Seeds? and What Does Autoflower Mean?.

Quebec Summer Seed-Starting Calendar (Practical Month-by-Month)

Late February to March (optional: planning + gear check)

• Pick genetics suited for Quebec’s outdoor season (shorter flowering, good resistance).
• Prep your seed-starting area: light, mild airflow, clean pots, and quality medium.
• Read: Growing Cannabis for Beginners

Mid-March to early April (best for long-flowering photoperiod strains)

• Start sativa-leaning or longer-flowering photoperiod seeds indoors.
• Keep seedlings warm and stable; avoid overwatering.
• Reference: How Long For Cannabis Seeds to Sprout

Early-to-late April (prime start for most photoperiod outdoor runs)

• Start most feminized photoperiod seeds indoors for a strong transplant by May.
• When planting into cups/pots, use correct depth: How Deep To Plant Cannabis Seeds

Mid-May to early June (transplant window for much of Quebec)

• Transplant after frost risk is realistically gone and nights are mild.
• Harden off seedlings for 7–10 days first (see section below).
• Outdoor starter page: Growing Outdoors in Canada

Late May to late June (autoflower sweet spot)

• Start autos outdoors once conditions are stable.
• If you want a head start, germinate indoors 2–3 weeks earlier and transplant carefully (autos dislike heavy stress).

July (optional: second autoflower run)

• In many summers, you can start a second round of autos in early July if your first finishes early and fall weather cooperates.
• Training autos for better structure: Training Your Autoflowers For Big Yields

Hardening Off (The Step Most People Skip)

Even if it’s “warm” outside, seedlings raised indoors need time to adapt to real sun, wind, and temperature swings. Hardening off reduces shock and helps plants explode in growth once transplanted.

• Days 1–2: 1–2 hours outside in bright shade, sheltered from wind
• Days 3–5: 2–4 hours, gradually increase sun exposure
• Days 6–10: longer outdoor periods, including morning sun
• Transplant day: choose an overcast day or late afternoon

Direct Sowing vs Transplanting (What’s Better?)

Starting indoors (recommended for photoperiod in Quebec)

• Earlier start = bigger plants by summer
• More control over early growth
• Better survival rate vs cold snaps

Direct sowing outdoors (best for warm, stable conditions)

• Works well for autos once late May/June weather is stable
• Less transplant shock
• Higher risk if spring nights are still cold

Strain Choice: Match Genetics to Quebec Summer

Timing isn’t only about dates—it’s also about genetics. If you choose long-flowering varieties, you’ll want to start earlier and/or pick “faster” finishing lines to avoid late-season issues.

• For short summers: autoflowers, fast finishers, and hardy outdoor genetics
• For big yields: photoperiod feminized strains started indoors in April
• For humid fall climates: strains with good airflow structure and solid resistance

And when fall comes, this guide helps you time your finish properly: The Perfect Time to Harvest Outdoor Cannabis Plants.

FAQ: Starting Cannabis Seeds for Summer

How many weeks before summer should I start seeds indoors?

For photoperiod outdoor grows in Quebec, many growers start indoors 4–8 weeks before transplanting after the last frost. Longer-flowering strains often benefit from starting earlier.

When is it safe to put seedlings outside in Quebec?

When frost risk has passed for your location and nights are consistently mild. Use average frost dates as a baseline, but always check your local forecast before transplanting.

Should I start autoflowers indoors or outdoors?

If conditions are stable, starting autos outdoors in late May/June is simple and effective. If you want a head start, keep it short (2–3 weeks indoors) and transplant carefully to avoid stress.

Legal Disclaimer: Cannabis laws vary by jurisdiction. It is the buyer’s responsibility to know and follow all local, provincial/state, and federal laws. These products are intended for adult customers (18+ or as required by law) where permitted. We do not encourage or promote any illegal activity.