# Planting Calculator — Vegetable Planting Calendar > Free vegetable planting calendar by frost date. See when to start seeds indoors, transplant, direct-sow and harvest each crop, then print or save as PDF. - **Category:** Date & Time - **Interactive calculator:** https://youcalc.com/en/date-time/planting-calculator/ - **Price:** Free, no sign-up required ## Overview This is a free, no-sign-up vegetable planting calendar. You enter your average last spring frost and first fall frost dates, pick your crops, and it works out — for each one — when to start seeds indoors, when to transplant or direct-sow outdoors, and when to expect the harvest, then lays it all out as a colour-coded month-by-month grid you can print or save as a PDF. Cold-hardy crops also get a second, fall sowing counted back from the first frost. Because the whole plan is stored in the page link, the shareable URL and the printed “Scan to revisit” QR code both reopen your exact calendar — nothing is stored on a server and no account is needed. It is hemisphere-agnostic (you supply your own frost dates, so it works in the Southern Hemisphere too), and a frost-free / tropical mode switches to a year-round sowing guide for climates without frost. ## How to read your result The results panel is the calculator. It shows your growing-season length (the days between your last spring and first fall frost), how many crops you have planned, how many you start indoors versus direct-sow, how many get a fall sowing, the date of your very first indoor sowing and your last expected harvest. The crop-by-crop table then gives every date per crop: start indoors, plant out (by transplant or direct sowing), the harvest window from the crop’s days-to-maturity, and any fall sowing date. The month-by-month grid below is the printable artifact — one row per crop, with coloured bands for starting indoors, transplanting, direct-sowing, growing, harvesting and fall sowing. ## Method The engine converts your last spring frost and first fall frost to Julian Day Numbers and works purely in whole days (no timezone or daylight-saving). For each crop it applies three offsets measured in weeks from the last frost — start-indoors, transplant and direct-sow — and projects the harvest window by adding the crop’s minimum and maximum days-to-maturity to the outdoor planting date. A fall sowing, for cold-hardy crops, is the first fall frost minus the crop’s days-to-maturity plus a 10–14 day short-day factor (University of Maryland Extension), included only when it falls after the spring planting. The growing-season length is simply the span between the two frost dates, and the planting-risk setting shifts the spring dates by a fixed number of days. The offsets, days-to-maturity ranges and hardiness come from cooperative-extension references (University of Maryland and Virginia Cooperative Extension), with frost-date methodology from NOAA NCEI and USDA. The calculation is a pure function with no clock or network access, so the same inputs always produce the same calendar. ## Example - **Setup:** Pick the “Temperate (Zone 7)” scenario — last spring frost around 15 April, first fall frost around 1 November — with the popular crops selected. - **Result:** You get a growing season of about 200 days. Tomatoes show start-indoors in early March, transplant out two weeks after the last frost, and a mid-summer harvest; peas and spinach are sown several weeks before the last frost and offered a fall sowing in late summer. The month grid shows the whole plan at a glance, ready to print. ## Frequently asked questions ### How does the planting calendar work out the dates? Every crop’s timing is expressed as an offset in weeks relative to your last spring frost — for example tomatoes start indoors about six weeks before the last frost and transplant out one to two weeks after it, while peas and spinach are sown several weeks before it. The calculator adds those offsets to the frost date you enter, then projects each harvest from the crop’s days-to-maturity. The offsets and maturity ranges come from US and UK cooperative-extension planting guides. ### Where do I find my last and first frost dates? Your “average last spring frost” and “first fall frost” are the typical 32°F (0°C) freeze dates for your area, published by national weather services from long-term climate normals (in the US, NOAA NCEI). Search your town plus “average frost dates”, or pick the closest climate scenario as a starting point and adjust. Note that a USDA hardiness zone is not a frost date — it describes how cold your winter gets, not when frost ends in spring, so this tool is driven by frost dates rather than zone. ### Does it work in the Southern Hemisphere or a tropical climate? Yes. Because you enter your own frost dates, the same “weeks relative to the last frost” calendar works unchanged in the Southern Hemisphere, where the last spring frost falls around August–October. For frost-free tropical climates that have no frost at all, switch to the frost-free / tropical mode: it drops the frost anchor and gives a year-round sowing guide, with warm-season crops sown in succession across the year and cool-season crops timed to the cooler or drier months. ### What is a fall (autumn) sowing, and how is it timed? Many cool-season crops — lettuce, spinach, kale, radish, beets, carrots, peas — can be sown again in late summer for a fall harvest. The calculator counts back from your first fall frost by the crop’s days-to-maturity plus a short-day factor of about 10–14 days (days shorten and growth slows in autumn), following the University of Maryland Extension rule, so the crop matures just before the frost. ### What does the planting-risk setting do? Average frost dates are a 50% probability — frost can still occur a week or two later. The cautious setting shifts your spring planting later by two weeks for a wider safety margin; the eager setting shifts it a week earlier if you are willing to protect seedlings and gamble on an early spring. It only moves the spring dates; your fall sowings stay anchored to the first fall frost. ### Can I share or reprint my planting plan later? Yes. Your whole plan — frost dates, climate mode, planting-risk setting and the crops you chose — is encoded in the page URL, so the share link and the printed “Scan to revisit” QR code both reopen the exact calendar. Nothing is stored on a server and no account is needed; print it or save it as a PDF to pin up in the shed. ## Related calculators - [Business Days Calculator](https://youcalc.com/en/date-time/working-days-counter/) - [Shift Pattern Calculator: 4-on-4-off, Panama, DuPont](https://youcalc.com/en/date-time/shift-pattern-calculator/) - [Timetable Calculator](https://youcalc.com/en/date-time/timetable-calculator/) ## Sources - https://www.ncei.noaa.gov/news/last-spring-freeze - https://planthardiness.ars.usda.gov/pages/how-to-use-the-maps - https://extension.umd.edu/resource/vegetable-planting-calendar - https://www.pubs.ext.vt.edu/426/426-331/426-331.html - https://www.rhs.org.uk/vegetables/seeds-sowing --- Interactive version: https://youcalc.com/en/date-time/planting-calculator/ · From YouCalc — https://youcalc.com