Vegetable Planting Calendar — Global

Soil temperature — not the calendar — is what tells you when to plant. Seed sown below its germination minimum sits and rots; the same seed in warm soil is up in days. Planting calendars are written for one place, so move a few hundred kilometres, change hemisphere or garden at altitude and the dates stop meaning anything. The three conditions a seed actually responds to — soil temperature, frost and day length — behave the same way everywhere. Learn to read them and you can plant correctly in any climate.

The method: observe, measure, decide

• Observe. Watch what your own garden does, not what a calendar says. When does standing water disappear in spring? Where does frost linger longest? Which corner warms first? A season of notes beats any regional average.
• Measure. Two instruments settle almost every timing question: a soil thermometer pushed 5-10cm (2-4in) into the bed at the same time each morning, and your own records of first and last frost. Soil temperature is the number that actually governs germination.
• Decide. Match the measurement to the crop's temperature class, then count backwards from your frost date using days-to-maturity. If the arithmetic does not fit your season, change the cultivar or the crop — not the date.

The seasonal wheel: what to sow, in either hemisphere

This is as close to a universal calendar as it is honest to get. It is organised by where you are in your own year rather than by month, because those are the same thing everywhere — the months just carry different names in each hemisphere. Find your current phase in the left column, read across.

Two adjustments this table cannot make for you. If you garden in the tropics, the meaningful division is wet season and dry season rather than warm and cold — substitute “start of the dry season” for “settled warmth” and treat sustained rain the way a temperate gardener treats frost. And if you garden above roughly 1,500 m, your nights stay cold long after your days turn warm, so use the phase your night temperatures put you in, not your afternoons.

This is exactly why the four regional editions of the planner exist as separate products, and why this one does not pretend to be a fifth region. The UK, USA and Canada editions can print real dates because they cover one climate each. This edition prints the method, the thresholds and the recording pages, and you supply the two numbers that make it yours.

Step one: know your crop's temperature class

Every vegetable falls into one of four classes. The class tells you what soil temperature to wait for and how much frost the crop tolerates.

Soil temperature chart for planting: all 22 crops

The figure that matters most is the minimum — the point below which seed sits in the ground and rots rather than germinating. Sowing at the minimum works but is slow; sowing 10°C (18°F) above it is usually where germination is fastest and most even.

9 crops in this list show no soil minimum, and that is not a gap in the data — broccoli, Brussels sprouts, cabbage, eggplant, garlic, onions, peppers, potatoes, sweet potatoes. Some are started indoors and transplanted; others are grown from sets, cloves, seed pieces or rooted slips rather than sown as seed. For those, the frost date and the crop's own start method govern timing, not a direct-sow soil reading.

Step two: measure your soil

Push a soil thermometer 5-10 cm (2-4 in) into the bed and read it at the same time each morning — early readings are the honest ones, because afternoon sun flatters the surface. Take readings for several consecutive days; a single warm day means nothing.

Step three: record your own frost dates

Regional frost averages are a starting point, not an answer. Elevation, slope, proximity to water and even a nearby wall shift frost timing by weeks within a single garden. One season of your own records beats any published average.

Step four: check the crop can finish

Add the crop's days to maturity to your intended planting date, then add two to three weeks for the slower growth that comes with shortening days. If that lands after your first frost, the crop will not finish. Change the cultivar or change the crop.

Day length matters too

Some crops respond to day length rather than temperature. Onions bulb according to hours of daylight, which is why a long-day cultivar fails near the equator and a short-day cultivar bolts at high latitude. Spinach and lettuce bolt as days lengthen past a threshold. Where a crop is day-length sensitive, the guides say so.

Southern hemisphere gardeners

Everything here applies unchanged. The conditions are identical; only the months differ. This is precisely why these guides avoid calendar months — a soil temperature threshold is true in October in Melbourne and in April in Madrid.

There is a practical consequence worth saying plainly: if you are reading this in August or September in Australia, New Zealand, South Africa, Chile, Argentina or southern Brazil, you are at the start of your planning season right now, not at the end of one. Everything on this page applies immediately. Northern-hemisphere gardening content will spend the next three months telling you to put the garden to bed, and every word of it will be exactly six months out of step with your soil.

The one thing that genuinely does differ is day length behaviour near the equator. Between roughly 10°N and 10°S, day length barely changes across the year, so the day-length triggers that make northern spinach and onions bolt on cue simply do not fire. If you garden there, ignore day-length guidance in imported growing advice and work from temperature and rainfall alone.

Frequently Asked Questions

How do I know when to plant without a calendar?

Measure soil temperature at 5-10 cm depth, know your own first and last frost dates, and match both against the crop's temperature class. That gives you a planting time specific to your garden rather than to a region.

What soil temperature should I plant at?

About 4-5C (40F) for hardy cool-season crops, 7-15C (45-60F) for half-hardy ones, above 15-16C (60F) for tender warm-season crops, and 18-21C (65-70F) for heat-loving crops such as sweet potato and okra.

Does this work in the southern hemisphere?

Yes, without modification. Soil temperature, frost tolerance and day length behave identically in both hemispheres — only the months differ, which is why this method avoids months entirely.

Why did my seeds rot instead of germinating?

Almost always because the soil was below the crop's germination minimum. Air temperature warms weeks before soil does, so a warm spell is not evidence that the ground is ready.

Do I really need a soil thermometer?

It is the single most useful instrument in a vegetable garden and costs very little. It answers the timing question that guesswork gets wrong most often.

Last updated 25 August 2026