Soil Temperature Checker
Your last frost date tells you when it stops freezing. It doesn't tell you whether the soil is warm enough for seed to germinate — and that's what decides whether your beans come up or rot. Pick your city for the real soil temperature at seeding depth.
Soil temperature at seeding depth, not the calendar date, decides whether a seed germinates or rots. Most cool-season crops germinate from about 7 to 10 °C, while beans, corn and squash need at least 15 °C, and peppers and melons want 18 to 21 °C. This tool reads the forecast soil temperature at 6 cm depth for your city — seeding depth — and reports the daily mean rather than the afternoon peak, then checks it against each crop's minimum germination temperature.
Pick your city to see your soil temperature.
Why soil temperature beats the calendar
Your last frost date tells you when it stops freezing. It says nothing about how warm the soil is — and a seed doesn't read the calendar.
A bean sown into 10 °C soil doesn't germinate. It takes up water, sits still, and often rots before the soil warms. That's the most common cause of a thin spring row.
It's also why the gardener who waits an extra two weeks usually overtakes the one who sowed early: in warm soil, emergence is fast and even.
Common questions
How deep should soil temperature be measured?
At seeding depth — roughly 2–5 cm for most seed. This tool reports 6 cm, the closest available reading. The surface is misleading: on a real Winnipeg day the 0 cm reading swung 11 °C in 24 hours (21 to 32 °C) because it tracks sunshine, while at 6 cm the swing was only 6 °C. If you're measuring yourself with a probe thermometer, push it in about 5 cm and read in the morning, before the sun has heated the surface.
Why the daily average rather than the current temperature?
Because a seed responds to sustained temperature, not the afternoon peak. That same Winnipeg day hit 28.8 °C at 6 cm in late afternoon but averaged 25.3 °C — quoting the peak would green-light sowing melons into soil that is really only middling. So the tool shows today's mean and a three-day mean; the multi-day trend is what matters, particularly in spring.
What happens if I sow into soil that's too cold?
The seed sits there and becomes vulnerable. A bean sown into 10 °C soil doesn't germinate — it takes up water, sits still for weeks, and often rots before the soil warms, or comes up very patchily. This is the single most common cause of a thin spring row. Waiting a week or two almost always gives better emergence than sowing early, and the crop catches up quickly once it's in warm soil.
How do I warm my soil faster in spring?
Cover the bed two to three weeks before you intend to sow. Black or clear plastic laid straight on the soil comfortably gains several degrees — clear warms more but also lets weeds germinate underneath. Raised beds warm faster than open ground because they drain better and are exposed on all sides. And pull mulch back in early spring: it keeps soil cold. Put it back once the soil has warmed.
Is this my garden's actual soil temperature?
No — it's a modelled figure for your locality, not a reading from your bed. Your real soil can differ by several degrees: a raised bed in full south-facing sun runs warmer, a shaded corner or heavy wet clay runs colder, and mulch holds soil cold longer in spring. Use this to know when it's worth going out to check, then confirm with a soil thermometer pushed in about 5 cm. They're inexpensive and settle the question.
Do lettuce and spinach have an upper limit?
Yes, and it's a genuinely useful quirk. Lettuce goes into thermodormancy: above roughly 25 °C soil, the seed actively refuses to germinate, which is behind a lot of failed summer sowings. Spinach behaves similarly. For a late-summer sowing, wait for soil to drop, sow late in the day, water to cool the bed, or pre-sprout the seed in the fridge for a few days before sowing.
Related tools
Soil temperature: Open-Meteo forecast at 6 cm depth for your locality — a modelled figure, not a reading from your bed. Germination thresholds are published agronomic values (extension services and seed companies), not measured data, and are kept consistent with the figures stated in our guides.