Sowing calendar: what to sow when, region by region

A sowing calendar is one of the most-searched pieces of information among new gardeners — and one of the most poorly explained. Most online sheets give a single date with no mention of which region, which soil, which method (indoor start or direct sow).

The result: people sow tomatoes outdoors on 15 April because "that's what it says", a frost hits on 25 April, and they blame the seeds. The seeds and the calendar weren't to blame — generalisation is what cost the harvest.

The data point that changes everything: your average last-frost date

Every meaningful sowing calendar is built on one foundational figure: the average date of the last spring frost in your area. From it, everything else is calculated — when to start seeds indoors, when to transplant outside, when you can finally drop the fleece.

Some examples (rough European reference points):

• Mild coastal areas, southern France, Mediterranean coast: late March to early April.
• Île-de-France, southern UK, central France, west coast plains: 1–15 May.
• Inland uplands, eastern France, Belgium, the Netherlands: 15–25 May.
• Mountain areas (Alps, Pyrenees, Vosges, Highlands): early June, sometimes later.

These dates are averages: some years frost surprises everyone in late April, others there's nothing to fear from mid-March. Hence the value of also listening to the immediate forecast, not just the historical mean.

Indoor start or direct sow? The choice that shapes your season

Indoor start (under cover, indoors or in a greenhouse)

This is for frost-tender, long-cycle plants: tomatoes, peppers, aubergines, basil, sometimes squash if you want a three-week head start. Seeds go into module trays or biodegradable pots at 18-22 °C, in full light, and you wait until the frost risk is gone before transplanting outdoors.

The rule of thumb: indoor start 6 to 8 weeks before transplant date. In a temperate climate where you plant out around 10-15 May, that means starting indoors around mid-March.

Direct sow (in the ground where the plant will stay)

This is for plants that resent transplanting (carrots, radishes, turnips, parsnips, beetroot, beans, spinach) or that don't need a head start (cut-and-come-again lettuce, chard, courgettes in mild climates).

The trigger: soil temperature. Below 8-10 °C, many seeds simply don't germinate. They sit, sometimes rot. Better to delay by ten days than push by impatience.

Season by season (temperate climate, adapt as needed)

This table is calibrated for a temperate maritime climate (think southern UK / northern France). Add two to three weeks in the south, subtract two to three at altitude or further north-east.

January — February

• Indoors: aubergines, peppers, chillies (long cycle, they need the head start).
• Under cover: onions, first lettuces.
• Outdoors: broad beans, peas as soon as the soil has dried out.

March

• Indoors: tomatoes, basil, celery.
• Under tunnel or cold frame: carrots, radish, lettuce, spinach.
• Outdoors (mild climates): carrots, radish, peas, onion sets.

April

• Indoors: squash, courgettes, cucumbers, melons (3-4 weeks before transplanting).
• Outdoors: French beans end of month (mild climates), lettuce, chard, beetroot, turnips, parsley.
• Plant: potatoes, shallots.

May

• After the last frost: transplant all the tender ones outside — tomatoes, peppers, aubergines, courgettes, basil.
• Outdoors: beans, sweetcorn, squash, cucumbers, beetroot, carrots (staggered).

June — July

• Keep staggering the short-cycle crops: cut-and-come-again lettuce (heat-tolerant varieties), French beans (every 3 weeks), summer radish, autumn turnips.
• First sowings for autumn: winter cabbages, leeks, spinach.

August — September

• Sowings for autumn and winter: lamb's lettuce, spinach, winter lettuce, turnips, winter radish, winter purslane.
• Plant: strawberries, garlic (around Michaelmas), overwintering onions.

October — November

• Outdoors: garlic, broad beans, peas for spring harvest.
• Green manure (mustard, phacelia) on free patches to protect and feed the soil.

The trap of generic calendars

The table above is useful but it is always an approximation. In an exceptionally warm March you can gain two weeks. In a cold wet April you lose three. A spring on the Mediterranean has nothing to do with a spring on the Atlantic, and a coastal spring isn't the same as one 50 km inland.

The only sustainable solution is to adapt the calendar to your real garden: your soil, your local climate, this year's weather, your method.

FloreSage handles your sowing calendar for you

The FloreSage app was built precisely to solve this problem. Instead of a fixed calendar valid "for everyone", you get one that fits you.

• You set your region, your climate, your soil type once.
• For every plant you choose, I know the full cycle — and I shift it automatically based on your zone.
• I pull local weather continuously. If a cold snap is on the way, I warn you before you plant — or I suggest covering up what's already in the ground.
• You tick as you go; the tasks that follow (transplant, mulch, first harvest) re-anchor automatically against your real sowing date. No more dead calendar that no longer matches anything.
• On the emblematic species — tomato, courgette, runner bean, lettuce, potato, strawberry… — I show you the named varieties worth knowing and their criteria: earliness, habit, frost resistance, culinary use. You pick a 'Beefsteak' rather than a "generic tomato", and your whole schedule adjusts to that variety.

You garden with your climate, not against it. And when a spring catches everyone off guard, I'm already on it.