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When to plant broccoli in Calgary

How to grow BroccoliCalgary climate
Where are you growing?

Comfortable

Comfortable in greenhouse

Comfortable in a cold frame

Broccoli in Calgary is a good fit outdoors. The suitable growing window of 166 days covers the 55–75 days this plant usually needs.

Start indoors
March 5 – April 29
Transplant outside
April 23 – June 17
Harvest
June 17 – August 31
Season vs crop
166 grow days vs 55–75 needed
Typical frost (last spring – first fall)
May 12 – October 13

Broccoli in Calgary is a good fit outdoors. The suitable growing window of 166 days covers the 55–75 days this plant usually needs.

Planting conditions

Broccoli planting activities across the year: Start indoors, Harden off, Transplant outside, Grow outdoors, HarvestJFMAMJJASOND~May 12~Oct 13
  • Start indoors
  • Harden off
  • Transplant outside
  • Grow outdoors
  • Harvest
Local activity windows for this place and growing method. Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost.
Suitable growing days in a row166
Days to harvest55–75 days from transplant
Mar 5 – Apr 29
Start indoors
Apr 16 – Apr 22
Harden off
April 23
Transplant outside
Apr 24 – Jun 16
Grow outdoors
Jun 17 – Aug 31
Harvest
ActivityWindowNotes
Start indoorsMar 5 – Apr 29Sow indoors before the outdoor window.
Harden offApr 16 – Apr 22Acclimate seedlings outdoors before planting.
Transplant outsideApril 23Move plants outside on this day (start of the plant-out window).
Grow outdoorsApr 24 – Jun 16Plants grow outdoors until harvest.
HarvestJun 17 – Aug 31Expected harvest from typical days to harvest.
Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost. Adjust a week or two for your conditions.

Planting and growing across the year

Planting is the sow / plant-out window. Growing is daytime air versus this plant’s ideal (15 – 24 °C) and tolerable (4 – 27 °C) ranges.

Broccoli planting and growing weeks in CalgaryJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECPlantingGrowing
Planting uses sow / plant-out rules (frost, soil germination, night, and last-sow): green when plantable, blue diagonal when nights or soil are too cold, amber cross-hatch when too hot, faint for other calendar limits. Growing shows daytime air against this plant’s ideal and tolerable ranges across the year.

Key dates

Typical last spring frostMay 12
Safer last spring frostMay 12
Typical first fall frostOctober 13
Safer first fall frostOctober 13
Frost-free days153
Earliest indoor seed startMarch 5
Latest indoor seed startApril 29
Transplant outdoorsApril 23 – June 17
Direct sow windownot recommended here
Suitable growing windowApril 23 – October 5 (166 days)
Expected harvestJune 17 – August 31

How these dates are judged

Ideal conditions
Daytime air from 15 – 24 °C.
Suitable conditions
Daytime air from 4 – 27 °C.
Last frost and first frost
Typical spring and fall frost dates for Calgary, shown in the key dates.
Days to harvest
55–75 days from transplant, from typical days to harvest.
Sowing window
Dated sow and harvest bars use frost dates, soil minima, night limits, and last-sow count-back from typical crop timing. The year strip and weekly chart use the same window: air ratings only colour weeks inside it.

Growing window for Broccoli: Apr 23 – Oct 5 (166 days)

Planting window for Broccoli: Apr 23 – Jun 17 (56 days)

Usually too cold: Jan 1 – Apr 19; Oct 5 – Dec 31

Outdoors: weekly temperatures and windows

Temperatures across the year for Calgary. Shaded bands are this plant’s ideal and tolerable daytime air ranges. Growing is daytime air suitability; Planting is sow / plant-out conditions (same colour language). Window brackets mark each stretch.

JanFebMarAprMayJunJulAugSepOctNovDec−50 °C−58 °F−40 °C−40 °F−30 °C−22 °F−20 °C−4 °F−10 °C14 °F0 °C32 °F10 °C50 °F20 °C68 °F30 °C86 °F40 °C104 °FTolerable 4–27 °CTolerable 39–81 °FIdeal 15–24 °CIdeal 59–75 °FWindowGrowingApr 23 – Oct 5PlantingApr 23 – Jun 17Last frost ~May 12First frost ~Oct 13
  • Ideal range
  • Tolerable range
  • Possible min to max
  • Average min to max
  • Suitable
  • Tolerable
  • Too cold
  • Too hot

Selected week · tap a week or use the arrows

Week 17 · Apr 20 – Apr 26

Average −2 to 11 °C · Possible −7 to 19 °C

Growing: too cold (inside window)

Planting: suitable

A week is in range when its average low and high sit inside the tolerance band 4 to 27 °C; it is suitable when that average range also overlaps the ideal 15 to 24 °C band and possible readings stay within 4 °C to 27 °C. Crossing a possible limit, or missing the ideal band, makes it tolerable; a possible low below 4 °C makes it tolerable. When a sowing window is calculated, weeks outside that window are uncoloured even if air is in range.

Based on average frost dates.

Show all 53 weeks
Cover method weekly charts

Outdoor weekly chart is above. Open a cover chart only if you grow under fleece, a cold frame, or an unheated greenhouse.

Other plants for Calgary

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

How we calculated this
  • Data: ERA5-Land via Open-Meteo, cell 51.00, -114.10, years 2019–2026 (not a 30-year climate normal yet).
  • Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
  • Crop rule: Local windows for Broccoli from frost dates, temperature ratings, and crop timing rules.
  • Confidence: Provisional — short or thin sample for this place.
  • Full methodology (algorithm 2026-10-season-6).

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