Growing vegetables from seed is one of those things that sounds intimidating until you’ve done it once. Then it feels almost obvious. A packet of seeds costs less than a coffee, makes 30 to 100 plants, and the moment those first green shoots push up out of the compost is genuinely brilliant. The whole season feels different once you’ve grown something from a seed you planted yourself.
This guide covers how to actually do it in UK conditions. What to sow indoors, what to sow direct, the timing that works in our climate, and the small details that make the difference between a tray of strong seedlings and a tray of disappointment.
Why Start From Seed Instead of Buying Plants
You can absolutely buy young vegetable plants from a garden centre and get a perfectly good harvest. Nothing wrong with that route. But growing from seed has some real advantages, and they’re worth knowing about before you decide which way to go.
The cost difference is significant. A packet of tomato seeds is around £2 to £3 for 30 to 50 seeds. A single young tomato plant is around £3 to £5. If you want six tomato plants from seed, you’ve paid £3 once. If you want six plants from a garden centre, you’ve paid £20 to £30. Multiply across an entire garden of crops and the difference adds up fast.
You also get far more choice from seed. Garden centres typically sell two or three common varieties of each crop. Seed catalogues have dozens. If you want a particular type of cherry tomato or a specific old-fashioned variety of beetroot, you’ll usually only find it as seed.
And honestly, it’s just more satisfying. There’s a different feeling about eating something you grew from a seed you put in compost back in March.
The Two Ways to Grow From Seed
There are really only two methods. You either sow seeds indoors and transplant the seedlings outside later, or you sow seeds directly into the ground where you want them to grow. Both methods work, but they suit different crops.
Sow indoors for anything that needs a longer growing season or a warm start. Tomatoes, courgettes, cucumbers, pumpkins, sweetcorn, French beans, runner beans, peppers, and basil all do best started indoors in pots or trays and moved outside when conditions are warm enough.
Sow direct for crops that don’t transplant well or grow quickly enough from a direct sowing. Carrots, parsnips, beetroot, radishes, salad leaves, peas, broad beans, spinach, and most root vegetables go straight in the ground where you want them.
Some crops can go either way. Lettuce can be started indoors and transplanted, or sown direct. Beetroot is the same. There’s no wrong answer, just different ways of getting to the same place.
What You Actually Need to Get Started
The amount of gear you actually need is much smaller than the gardening industry would like you to believe. Here’s what genuinely helps:
Seed trays or small pots. Old yoghurt pots with holes punched in the bottom work just as well as anything you can buy. Bigger seeds like beans, pumpkins, and courgettes need individual pots about 9cm wide. Smaller seeds like tomatoes and lettuce go in seed trays or modules.
Compost. Use a peat-free multipurpose compost or a dedicated seed compost. Don’t use garden soil, it’s too dense and full of weed seeds. Best Compost for Vegetables in the UK covers what to look for and what to avoid.
Somewhere warm and bright. A south-facing windowsill is fine for most things. A heated propagator helps with anything that needs higher temperatures to germinate, but it’s not essential to get started.
Labels. Sounds obvious until you’ve got six trays of green seedlings that all look identical. Lolly sticks and a pencil work fine.
That’s it. You don’t need grow lights, heated mats, special tools, or expensive equipment. Plenty of brilliant gardeners have been growing vegetables successfully for decades with nothing more than this.
How to Sow Seeds Indoors
The process is more straightforward than people expect. Fill your tray or pot with compost, level it off, give it a gentle tap to settle. Don’t compact it down hard, seeds need air around them to germinate properly.
Sow at the depth listed on the seed packet. As a rule of thumb, seeds are sown at about twice their own depth. Small seeds like lettuce barely need covering. Bigger seeds like beans go in about 2 to 3cm deep. If in doubt, err on the shallow side rather than the deep side.
Water gently from the top with a fine rose or by sitting the tray in a shallow dish of water for 20 minutes. Heavy watering washes seeds out of position. Cover with cling film or a clear lid to keep moisture in, and put it somewhere warm and bright.
Check daily. As soon as you see green shoots emerging, remove any covering. Keep the compost moist but not waterlogged, and turn the tray every couple of days so seedlings don’t grow lopsided toward the light. Why Tomato Seedlings Go Leggy in the UK covers what to do if seedlings start stretching and going thin, which is the most common indoor sowing problem.
How to Sow Seeds Direct Outside
Direct sowing is even simpler in some ways. The main thing that matters is timing and soil condition.
The soil needs to be warm enough for the seeds to germinate. If it’s still cold and wet, most seeds will rot before they sprout. When Is Soil Warm Enough to Plant Vegetables covers the soil temperatures different crops need. A simple test: if the ground feels properly cold when you press your hand into it, it’s too soon.
Rake the soil to a fine, level surface. Make a shallow drill (a straight line groove) with the corner of a hoe or a stick. Sow seeds along the drill at the spacing on the packet, cover with soil, and water gently. Label the row.
The temptation with small seeds is always to sow them too thickly. Resist it. Thick sowing leads to overcrowded seedlings that compete with each other and all underperform. It’s much better to sow thinly from the start, but if you do end up with too many seedlings, thin them properly. When to Thin Vegetable Seedlings in the UK shows when and how to do it.
Hardening Off Before Planting Out
This is the step everyone wants to skip and it’s the step that matters most. Plants grown indoors have been living in still, warm, soft conditions. Outside it’s windy, the temperature swings, the sun is brighter, and the air is drier. Moving plants straight from indoors to outside is a shock that can stall growth for weeks.
Hardening off means gradually getting them used to outdoor conditions over a week or two. Start by putting them outside in a sheltered, shaded spot for a few hours during the day, then bringing them back in at night. Build up the time gradually until they’re outside day and night for a few days before going in the ground permanently.
It feels fiddly but it makes a real difference. Plants that have been properly hardened off settle into the garden quickly and start growing again within days. Plants that haven’t often sit there sulking for weeks. How to Harden Off Plants in the UK covers the full process step by step.
When to Sow What in the UK
Timing matters more than almost anything else when growing from seed in the UK. Get the timing right and seeds germinate quickly and grow strongly. Get it wrong and the same packet that would have produced 30 plants gives you nothing.
The broad pattern across the UK looks like this:
February to March: Indoor sowing of tomatoes, peppers, and other crops that need a long season. Direct sowing of broad beans, onion sets, and very early peas if the soil allows.
April: Indoor sowing of courgettes, cucumbers, pumpkins, sweetcorn. Direct sowing of carrots, beetroot, parsnips, radishes, spinach, lettuce.
May: The busiest sowing month. Direct sow almost everything that isn’t already in. Indoor sowings continue for tender crops not yet started. What to Sow in May in the UK has the full list.
June: Continue direct sowing of beans, salad leaves, beetroot, carrots, and succession crops. Start sowing winter brassicas like kale and purple sprouting broccoli for autumn and winter harvests.
July onwards: Less common but still worth doing. Salad leaves, spring onions, and quick-growing crops can be sown through to August for autumn harvests.
For the full year on one page, the UK Vegetable Planting Calendar shows every crop month by month, and When to Plant Vegetables in the UK covers the same in more detail.
Easy Vegetables to Start With
If you’ve never grown from seed before, some crops are much more forgiving than others. These five are almost impossible to mess up and will give you a satisfying first season:
Lettuce. Germinates fast, grows quickly, ready to harvest in about six weeks. Can be sown direct or indoors. When to Plant Lettuce in the UK has timing details.
Radishes. The fastest crop you’ll grow. Direct sown in spring, ready to eat in 4 to 6 weeks. Great for kids and good for confidence.
Beetroot. Reliable, easy, productive. Direct sow from April through July. See When to Plant Beetroot in the UK.
Courgettes. One indoor sowing in April or May gives you so many courgettes by August you’ll be giving them away. When to Plant Courgettes in the UK covers the process.
Peas. Forgiving, quick to germinate, and far better fresh from the garden than anything you can buy. When to Plant Peas in the UK covers timing.
For a wider list of beginner-friendly crops with more detail on each, Easy Vegetables to Grow in the UK is worth reading too.
Common Mistakes (And How to Avoid Them)
The same handful of mistakes catches almost every beginner. Knowing them in advance saves a lot of frustration:
Sowing too early. The biggest one. A warm March or early April day makes everyone want to get seeds in, but soil temperatures haven’t caught up. Cold soil means seeds rot rather than germinate. Wait for warmth. What Happens If You Plant Vegetables Too Early covers why this backfires so often.
Sowing too thickly. Always feels like you should sow more “in case”. You don’t need to. Sow thinly, you’ll have plenty of plants.
Overwatering. Damp compost is good. Soggy compost rots seeds. The surface should look just slightly damp, not wet.
Not enough light. Seedlings on a dim windowsill grow tall, pale, and weak. They need bright light from the moment they emerge, not warmth. A south-facing windowsill is best.
Skipping hardening off. Mentioned earlier but worth repeating. It’s the single most common reason indoor-grown seedlings fail when they go outside.
Planting out too early. Beginners who do everything right indoors often blow it at the end by putting tender plants outside before frost risk has passed. UK Last Frost Date Checker tells you your safe planting date.
How Long Seeds Last
One useful thing to know: most vegetable seeds last for years if stored properly. You don’t need a fresh packet every season. Keep seeds dry, cool, and out of direct sunlight (a tin or sealed bag in a kitchen drawer is fine), and most will stay viable for 3 to 5 years.
The main exceptions are parsnips and onions, which lose viability quickly. Buy fresh parsnip seed every year. Most other crops, an opened packet from two years ago will still produce a perfectly good harvest.
If you’re not sure whether old seeds are still good, do a quick germination test. Put 10 seeds between damp kitchen towel inside a sealed plastic bag, keep it somewhere warm, and check in a week. If 7 or 8 germinate, the packet is still fine. If only 2 or 3, it’s probably time for a fresh one.
Frequently Asked Questions
Is it cheaper to grow vegetables from seed than to buy plants?
Yes, by a significant margin. A packet of seeds typically costs £2 to £3 and produces 30 to 100 plants. The same number of young plants from a garden centre would cost £100 or more. Even with the cost of compost and pots factored in, growing from seed is far cheaper.
Do I need a greenhouse to grow vegetables from seed in the UK?
No. A warm, bright south-facing windowsill is enough for almost all vegetable seedlings. A greenhouse helps if you want to grow larger quantities or extend the season, but it isn’t necessary for getting started.
What’s the easiest vegetable to grow from seed in the UK?
Lettuce, radishes, beetroot, courgettes, and peas are the easiest crops for beginners. They germinate reliably, grow quickly, and are forgiving of small mistakes. Radishes go from seed to harvest in around six weeks.
When can I start sowing seeds in the UK?
It depends on the crop. Tomatoes and peppers can be sown indoors from February. Most tender crops like courgettes and cucumbers go in indoors in April. Direct outdoor sowing of hardy crops like carrots, peas, and lettuce can start from March to April once the soil is warming up.
Why are my seedlings tall and thin?
This is called leggy growth and is usually caused by not enough light. Seedlings stretch towards weak light sources and become tall, pale, and weak. Move them to a brighter spot, ideally a south-facing windowsill, and they’ll grow stockier.
How long do vegetable seeds last?
Most vegetable seeds last 3 to 5 years if stored cool, dry, and away from sunlight. Parsnips and onions are exceptions and should be replaced annually. You can test old seeds by germinating 10 between damp kitchen towel to see what percentage are still viable.
Should I sow seeds indoors or direct outside?
Sow indoors for tender crops that need a long warm season (tomatoes, courgettes, cucumbers, pumpkins, beans, basil) and direct outside for crops that don’t transplant well (carrots, parsnips, beetroot, radishes, peas, salad leaves). Some crops like lettuce can be done either way.
A Sensible Place to Start
If you’ve never grown from seed before, pick three crops, not fifteen. Lettuce and radishes give you a quick win in the first month. Courgettes from an April indoor sowing give you a proper crop by summer. That’s enough for a first season. You’ll learn what works in your conditions, and next year you can scale up confidently.
The seeds will surprise you. There’s something genuinely satisfying about going from a small dry packet in your hand to plants producing food in your kitchen. It’s also one of the cheaper, slower, more useful things you can do with an afternoon. Worth doing.
If you’re still working out what to grow, Easy Vegetables to Grow in the UK covers the best beginner crops, and the UK Vegetable Planting Calendar shows you exactly when to sow each one.