Practical planning tools for short growing seasons.

Garden climate data

Garden Climate Data for Frost Dates, Growing Degree Days and Crop Timing

Explore datasets for frost dates, growing degree days, crop heat requirements, city climate rankings, and short-season crop suitability. These pages are built as clear, linkable references for gardeners, writers, and researchers.

Core Garden Climate Datasets

These are the main reference datasets for season length, frost dates, seasonal heat, and crop timing.

Frost dates

Frost Dates by City

Average last spring frost, first fall frost, and frost-free growing-season length by city.

Growing degree days

Growing Degree Days by City

Seasonal heat accumulation for comparing warm-season crop potential across locations.

Crop heat needs

Crop Heat Requirements

Typical crop GDD targets used to compare crop needs against local seasonal heat.

Maps and Visual Climate Explainers

These resources turn climate and crop-timing data into visual comparisons and plain-English explanations.

Climate atlas

Canada Garden Climate Atlas

Compare Canadian cities by frost-free days and base-50°F growing degree days using map-style views and regional summaries.

Climate atlas

U.S. Garden Climate Atlas

Compare U.S. cities by frost-free days and base-50°F growing degree days using map-style views and state summaries.

City Climate Rankings

Compare cities by frost-free season length, seasonal heat, and other garden climate signals.

Crop Suitability and Short-Season Risk

Compare crops by how demanding they are in cool, short, or timing-sensitive growing seasons.

Late planting risk

Late Planting Penalty Chart

See which crops lose the most growing margin when planting slips by two weeks, and which are more forgiving.

Crop-Specific Climate Studies

These pages apply the same frost, heat, and crop-timing data to specific garden crops and crop-location combinations.

Northern U.S. tomatoes

Best U.S. Northern Cities for Tomatoes

Northern U.S. cities ranked by outdoor tomato suitability, heat margin, frost-free days, and variety flexibility.

219 items ranked.

Northern U.S. peppers

Best U.S. Northern Cities for Peppers

Northern U.S. cities ranked by outdoor pepper suitability, heat margin, frost-free days, and variety flexibility.

219 items ranked.

How the data works

Climate Data Interpretation and Limitations

GrowByDate combines public climate normals, frost-date estimates, growing degree day calculations, and crop maturity assumptions to create garden-focused planning datasets. The rankings and comparison pages are derived from those underlying climate and crop-timing signals.

  • Climate records and normals are used to estimate typical seasonal conditions such as frost timing and heat accumulation.
  • Growing degree days estimate usable seasonal warmth in a way that is more crop-relevant than calendar days alone.
  • Crop maturity assumptions help compare crop heat needs against local frost windows and seasonal heat.
  • Derived GrowByDate metrics translate the reference data into rankings for city climate, crop difficulty, late planting risk, and crop-location suitability.

These datasets are for long-term planning and comparison, not short-term weather forecasting. Averages cannot capture every slope, cold pocket, raised bed, windy site, urban heat island, lake effect, soil condition, irrigation pattern, pest issue, or variety difference. Use the data to make better starting decisions, then adjust with local forecasts and what you know about your own garden.

Sources and methodology

Use these official references to verify the climate-normal, frost-date, and growing degree day concepts behind the GrowByDate data hub.

These links support the reference concepts behind the page. GrowByDate values are planning averages, not live forecasts or guarantees for a specific garden bed.