When to plant spinach in Riverside

Where are you growing?

Comfortable

Comfortable in greenhouse

Comfortable in a cold frame

Spinach in Riverside is a good fit outdoors. The suitable growing window of 119 days covers the 35–50 days this plant usually needs.

When to plantDecember 25 – May 4

Harvest: February 5 – April 22
Season vs crop: 119 grow days vs 35–50 needed
Typical frost (last spring – first fall): February 5

Spinach in Riverside is a good fit outdoors. The suitable growing window of 119 days covers the 35–50 days this plant usually needs.

Planting conditions

Direct sow
Harvest

Local activity windows for this place and growing method.

Suitable growing days in a row119

Days to harvest35–50 days from seed

Dec 25 – May 4

Direct sow

Feb 5 – Apr 22

Harvest

Activity	Window	Notes
Direct sow	Dec 25 – May 4	Plant outdoors in this window.
Harvest	Feb 5 – Apr 22	Expected harvest from typical days to harvest.

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 (59 – 70 °F) and tolerable (39 – 75 °F) ranges.

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 frostFebruary 5

Safer last spring frostFebruary 5

Frost-free daysNot yet (short archive)

Outdoor sow dateDecember 25

Direct sow windowDecember 25 – May 4

Suitable growing windowDecember 25 – April 22 (119 days)

Expected harvestFebruary 5 – April 22

How these dates are judged

Ideal conditions: Daytime air from 59 – 70 °F.
Suitable conditions: Daytime air from 39 – 75 °F.
Last frost and first frost: Typical spring and fall frost dates for Riverside, shown in the key dates.
Days to harvest: 35–50 days from seed, 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 Spinach: Jan 1 – Apr 22; Dec 25 – Apr 22 (231 days)

Planting window for Spinach: Jan 1 – May 4; Dec 25 – May 4 (255 days)

Outdoors: weekly temperatures and windows

Temperatures across the year for Riverside. 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.

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 1 · Jan 1 – Jan 4

Average 40 to 62 °F · Possible 31 to 79 °F

Growing: tolerable

Planting: suitable

A week is in range when its average low and high sit inside the tolerance band 39 to 75 °F; it is suitable when that average range also overlaps the ideal 59 to 70 °F band and possible readings stay within 39 °F to 75 °F. Crossing a possible limit, or missing the ideal band, makes it tolerable; a possible low below 39 °F 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 Riverside

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 33.95, -117.40, 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 Spinach 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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