Seasonal vegetables in the garden: sowing and harvesting cal

In short:

Timing matters more than tools or luck when it comes to growing food.
Learn your own frost dates and how your soil warms up before you sow anything.
Sow in small batches through four windows instead of one big push.
Succession sowing keeps you eating steadily instead of facing a glut then nothing.
When in doubt, wait — the garden rewards patience over rushing.

A garden that feeds you from April to February doesn’t happen by accident. It happens because someone, at some point in the dead of winter, sat down with a calendar, a stack of seed packets and a pencil, and worked out what goes where — and when.

Most disappointing harvests have nothing to do with bad soil or bad luck. They come from good intentions meeting bad timing. Seeds dropped into cold, soggy ground in March rot instead of sprouting. Lettuce sown in one enthusiastic batch in May turns into a hundred heads at once, then nothing for weeks. Tomatoes planted out too early sulk in chilly soil while a later planting overtakes them.

This guide walks through the whole year, season by season, with the practical logic behind each sowing window and each harvest moment. No rigid rules that only work in one postcode — instead, a framework you can bend to your own patch of ground, whether that’s a windswept allotment, a sheltered back garden or a few deep containers on a sunny terrace.

Start with your own rhythm: frost dates, microclimate and day length
The four sowing windows and when to use each one
Spring: cool-season crops and the first outdoor sowings
Summer: warmth-loving crops and the art of succession
Autumn: the second harvest and crops that overwinter
Winter: protection, slow growth and next year’s plan
Harvesting at peak: reading the signs and storing the surplus
The mistakes to avoid
Care, lifespan and when to replace
A real-world example: one bed, twelve months
Frequently asked questions
Putting the calendar to work

Start with your own rhythm: frost dates, microclimate and day length

Illustration : What vegetables can I sow each season? — Photo : Helena Lopes / Pexels

Every sowing calendar in every book is a rough sketch of somebody else’s garden. The useful version is the one you build for your own ground, and it starts with two dates: the average last frost of spring and the average first frost of autumn. Those two markers define the length of your growing season, and everything else hangs off them.

They are averages, not promises. A late frost can arrive a fortnight after the “safe” date, and an early one can cut a warm autumn short. That’s why the smartest approach is to work in windows rather than single days. Sow hardy crops two to three weeks before the expected last frost, tender crops a week or two after it, and keep a roll of horticultural fleece within arm’s reach until the risk has genuinely passed.

Then there’s your microclimate — the local quirks that shift those dates by weeks. A garden on a south-facing slope, sheltered by a wall or a hedge, warms up fast and drains well. A plot at the bottom of a hill, where cold air pools on still nights, behaves like somewhere much further north. Two gardens a short drive apart can easily differ by three weeks in what they can sow and when.

A concrete example: a raised bed against a south-facing brick wall may hold enough warmth for an early sowing of radishes and spinach in late February, while an open bed thirty metres away is still frozen solid at the same moment. The wall radiates stored heat overnight, and the soil behind it stays workable. Same garden, same seeds, three weeks apart.

Day length matters too, and it’s the factor gardeners forget most often. Spinach, rocket and coriander sown in the long days of June will bolt — run to flower — almost before you’ve picked a leaf. Sow the same seeds in September and they’ll sit happily for months. The calendar isn’t just about temperature; it’s about hours of light.

My recommendation: keep a simple notebook. Record the date of the last spring frost, the first autumn frost, and the day your first tomato ripens. After three years you’ll have a personal calendar more accurate than any chart, because it’s measured in your soil, under your sky.

The four sowing windows and when to use each one

Almost every vegetable you’ll ever grow fits into one of four approaches. Understanding which one suits which crop — and which moment — removes most of the guesswork.

Direct sowing means putting seed straight into the ground where the plant will live. It suits crops that resent root disturbance: carrots, parsnips, beetroot, radishes, spinach, beans, peas, sweetcorn and most salad leaves. It’s cheap, fast and low-fuss, but it leaves young seedlings exposed to slugs, birds and dry spells.

Indoor sowing and transplanting gives you a head start. You raise seedlings in trays or modules in warmth, then move them out once the weather allows. Tomatoes, peppers, aubergines, brassicas, leeks, celery and squash all benefit. The trade-off is space, attention and the need to harden plants off gradually before planting out — a week of short daytime trips outside, extended little by little.

Succession sowing is the technique that separates a garden with a glut from one with a steady supply. Instead of sowing a whole row of lettuce in one go, you sow a short row every ten days to a fortnight through the season. The same logic works for radishes, spinach, beetroot, carrots and bush beans. Small, frequent sowings flatten the harvest curve.

Overwintering and autumn sowing exploits the fact that some crops grow slowly through the cold months and explode into growth in early spring. Broad beans, garlic, winter lettuce, mâche and hardy Asian greens all fit here.

Method	Best suited to	Main advantage	Watch out for
Direct sowing	Carrots, parsnips, radish, beans, peas, spinach, salad leaves	No root disturbance, quick and inexpensive	Slugs, birds, drying out before germination
Indoor sowing + transplanting	Tomatoes, peppers, squash, brassicas, leeks, celery	Earlier harvests, better control over spacing	Needs hardening off; weak plants stall after planting
Succession sowing	Lettuce, radish, spinach, beetroot, bush beans	Continuous supply instead of one huge flush	Requires discipline and a written record
Autumn / overwintering	Broad beans, garlic, winter salads, mâche	Very early crops the following year	Waterlogging and wind damage in exposed spots

A concrete example: a single two-metre row of radishes sown on the first of May delivers perhaps forty roots, all ready within the same ten days. Nobody eats forty radishes in a week. Split that same row into four sowings a fortnight apart, and you get ten crisp roots every ten days for six weeks — the same seed, the same space, a far better outcome.

Spring: cool-season crops and the first outdoor sowings

Spring is the season that tempts everyone into rushing, and the season that punishes it hardest. The soil is still cold, the light is climbing fast, and the difference between a seed that germinates and one that rots comes down to a few degrees of soil temperature.

Start with the hardy, cold-tolerant crops. Broad beans, peas, spinach, radish, beetroot, early carrots, lettuce and onion sets can all go in as soon as the ground is workable and no longer waterlogged. These are the crops that shrug off a light frost and actually prefer cool conditions — lettuce sown in heat germinates poorly and bolts early.

Under cover or on a warm windowsill, spring is when you start the long-season tender crops. Tomatoes, peppers, aubergines and celery need a long run-up to fruit, so they go in early indoors and only move outside once nights are reliably mild. Squash, courgettes and sweetcorn follow a few weeks later — they grow fast and resent being checked by cold.

The key spring discipline is patience with tender crops. A tomato planted out into soil that’s still cold will sit and sulk for weeks, while one planted a fortnight later into warm ground overtakes it entirely. Cold soil doesn’t just slow growth; it invites root problems and yellowing leaves.

Summer: warmth-loving crops and the art of succession

By early summer the garden is in full flight, and the temptation is to stop sowing and start admiring. That’s a mistake. Summer sowing is what fills the gap that opens in late summer and autumn, when the spring crops are finished and the winter ones haven’t started.

This is the moment for successional salad, radish, beetroot and bush beans — short rows every ten days or so, kept watered. It’s also the window for the crops that will carry you into winter: winter brassicas, kale, leeks, chicory, fennel and late carrots. Sown now, they establish while the soil is warm and grow steadily into the cold.

Summer is also when watering becomes the limiting factor. Seeds sown into dry soil simply don’t germinate, and seedlings that dry out once may never recover. A mulch of garden compost or grass clippings keeps moisture in and roots cool, and it saves a great deal of watering later.

Watch the day length here. Anything sown in midsummer that’s sensitive to long days — spinach, rocket, coriander, some lettuces — will bolt quickly. Either choose bolt-resistant varieties, sow them in light shade, or save them for the shorter days of late summer.

Autumn: the second harvest and crops that overwinter

Autumn is the most underrated sowing season. The soil is still warm from summer, the light is gentler, and pests are winding down. Seeds sown now germinate quickly and grow steadily without the stress of heat.

This is the window for winter salads — mâche, lamb’s lettuce, hardy Asian greens, winter lettuce and land cress — plus overwintering broad beans and garlic. Planted in autumn, garlic and broad beans establish roots before the cold and then surge into growth in early spring, giving you crops weeks ahead of anything sown in February.

The main risks are waterlogging and wind. Raised beds or a little grit worked into heavy soil helps drainage, and a windbreak of netting or a low hedge protects exposed plots. Cloches and fleece extend the season further, keeping winter salads pickable well into the cold.

Autumn is also the season for clearing and feeding. As crops come out, don’t leave the ground bare — sow a green manure or spread compost, so the soil life keeps working through winter and you start spring with better structure.

Winter: protection, slow growth and next year’s plan

Very little germinates outdoors in the depths of winter, but the garden isn’t asleep. Overwintering crops are quietly growing roots, and the winter months are when the planning for next year actually pays off.

Under cover — a cold frame, a greenhouse, a bright windowsill — you can start the earliest sowings: onions from seed, early brassicas, hardy lettuce, and the first tomatoes if you have real warmth and light. These early starts need careful management, because weak, leggy seedlings from low winter light rarely catch up.

Outdoors, the work is protection and preparation. Check stored crops for rot, keep fleece handy for hard frosts, and make sure pots and raised beds drain freely. Then sit down with that notebook and plan: what worked, what didn’t, what you’ll sow less of and what you’ll sow more of. The best sowing calendar is written in winter and tested in summer.

Harvesting at peak: reading the signs and storing the surplus

Knowing when to pick is as important as knowing when to sow. Most vegetables tell you clearly, if you know what to look for. Salad leaves are best picked young and often — cut-and-come-again keeps plants productive for weeks. Beans and peas should be picked every couple of days while pods are still tender; leave them and the plant stops producing.

Root crops are more forgiving. Beetroot is sweetest at golf-ball size, carrots at finger thickness, and both can be left in the ground for a while if you need them later. Tomatoes ripen best on the vine but will finish ripening indoors at the end of the season. Squash is ready when the skin is hard enough to resist a fingernail and the stem has begun to cork.

Surplus is a good problem, but only if you deal with it. Freeze beans and peas blanched, store onions and garlic dry and airy, and turn gluts of tomatoes, courgettes and fruit into sauces and chutneys. Sharing with neighbours is the oldest storage method of all.

The mistakes to avoid

Sowing too early. The single most common error. Cold soil and cold nights cost more than they gain.
Sowing everything at once. A glut followed by famine is a planning problem, not a growing one.
Ignoring the seed packet’s own guidance. It’s written for your climate zone, not someone else’s.
Forgetting to harden off. Seedlings moved straight from warmth to wind and sun often stall or scorch.
Not labelling. A row of identical seedlings tells you nothing about what’s where.
Letting crops run to seed. Bolted plants stop producing; pick regularly to keep them going.

Care, lifespan and when to replace

Most vegetable plants are annuals — they complete their life in one season and are replaced each year. A few, like chives, rhubarb and some herbs, are perennial and come back reliably for years if divided and fed. Knowing which is which stops you pulling out something that would have returned.

Ongoing care is mostly about water, feed and airflow. Water deeply and less often rather than little and often, which encourages shallow roots. Feed heavy croppers like tomatoes and courgettes through the season, and keep plants spaced so air moves freely — good airflow prevents most fungal problems before they start.

Replace seed each year where germination matters most. Old seed loses viability gradually, and a packet that’s been in a warm drawer for three years will disappoint. Store seed cool and dry, and test a few on damp paper before committing a whole row.

A real-world example: one bed, twelve months

Picture a single raised bed, roughly a metre wide and three metres long, in a typical temperate garden. It’s not large, but with a little planning it can produce something to eat in almost every month of the year. Here’s how a realistic year might unfold.

Late winter. The bed is still holding overwintering broad beans sown the previous autumn, plus a patch of mâche under a cloche. Nothing new is sown outdoors yet, but a tray of early lettuce and onion seedlings sits on a bright windowsill indoors, waiting for the light to improve.

Early spring. The broad beans are flowering and the mâche is being picked leaf by leaf. A short row of radishes and a row of spinach go in at the sunny end, under fleece for the first couple of weeks. The lettuce seedlings are hardened off and planted out under a cloche.

Late spring. The radishes are finished and the space is resown with beetroot. Spinach is cropping heavily, so it’s picked often to stop it bolting. A couple of tomato plants in large pots sit at the warm end of the bed, and a row of bush beans is sown once the soil is properly warm.

Summer. Beans are picked every other day. The beetroot is pulled at golf-ball size and the gaps resown with late carrots. A short row of winter kale and leeks goes in where the early spinach was, so they establish while the soil is still warm. Salad is sown in small pinches every ten days in a shady corner.

Early autumn. Tomatoes are ripening fast and the last of them are brought indoors to finish. The kale and leeks are growing strongly. Garlic cloves go in at the far end, and a row of overwintering broad beans is sown alongside. Winter salads — mâche and hardy greens — are sown under fleece.

Late autumn and winter. The bed is mostly quiet but not empty. Leeks stand through the frost, kale keeps producing, and the overwintering broad beans and garlic are quietly rooting. Compost is spread over the bare patches, and the notebook comes out to plan next year — what grew well, what took up too much room, and what to sow less of.

The lesson from this example isn’t the specific crops — those will vary with climate and taste. It’s the rhythm: something finishing, something starting, and a small amount of space always in transition. That’s what turns a bed from a one-off project into a continuous supply.

Frequently asked questions

What is the best month to start a vegetable garden?

There’s no single month that works everywhere, because it depends on your local frost dates. In most temperate climates, early to mid-spring is the natural starting point for outdoor sowing, once the soil has warmed and dried enough to be workable. But the real answer is that the best month is the one that matches your own last frost date — hardy crops can go in a few weeks before it, tender crops a week or two after. If you want to start earlier, begin indoors or under cover in late winter.

Is there a free vegetable garden planner available in the UK?

Yes — several gardening organisations, seed suppliers and allotment associations publish free sowing and planting calendars, and many are available online at no cost. The catch is that they’re generic: they’re built around average conditions, not your specific plot. Use a free planner as a starting framework, then adjust the dates using your own frost dates and observations. A simple notebook or spreadsheet you build yourself is often more accurate than any ready-made chart, and it costs nothing.

What vegetables to plant this month?

It depends entirely on the month and your climate, but a rough guide helps. In early spring, focus on hardy crops: broad beans, peas, spinach, radish, early carrots and lettuce. In late spring and early summer, move to warmth-lovers: beans, courgettes, sweetcorn and tomatoes once nights are mild. Midsummer is for successional salad and winter brassicas. Autumn is for garlic, overwintering broad beans and winter salads. In the depths of winter, sow under cover or plan for spring.

How should I arrange my vegetables in my garden?

Start with the plants that need the most sun and space — tomatoes, courgettes, beans — and give them the warmest, most sheltered spot. Put low, fast-growing crops like lettuce and radish in front of or between taller ones so nothing is shaded out. Group crops by how much water and feeding they need, and rotate families between beds each year to reduce pests and disease. Tall crops at the back or north side, low crops at the front or south side, is a simple rule that works in most gardens.

Can I sow the same vegetables every month?

Some, yes — salad leaves, radish and spinach can be sown in small batches through much of the year, though midsummer sowings bolt quickly and midwinter sowings need protection. Others, like tomatoes, squash and sweetcorn, have a single narrow window and won’t thrive outside it. The trick is to know which crops are flexible and which are not, and to sow the flexible ones little and often.

What if my seedlings don’t come up?

Check three things in order: temperature, moisture and seed viability. Cold soil is the most common culprit — most seeds need consistent warmth to germinate. Next, check that the soil hasn’t dried out or become waterlogged. Finally, consider the seed itself: old seed germinates poorly, so test a few on damp paper before sowing a whole row. If all three are fine, give it another week — some crops are simply slower than others.

Putting the calendar to work

The whole point of a sowing calendar isn’t to follow it rigidly. It’s to give you a rhythm to work with — a sense of what’s possible now, what’s coming next, and what to hold back. Once you know your frost dates, your microclimate and how your soil behaves, the calendar becomes a tool rather than a rulebook.

Start small. Pick a handful of crops you actually like eating, sow them in modest batches, and note what happens. Add a little more each season. Within a couple of years you’ll have a personal calendar that’s more useful than any chart, because it’s built on your own ground and your own weather.

If you’re setting up your first proper growing space and want to get the basics right before you sow, it’s worth reading our guide to choosing raised beds and planters — good structure and drainage make every sowing window easier to use.

Put it into practice : How do you wash garden vegetables?