When to Plant Herb Seeds UK: Month by Month

A sunny windowsill, a small pot and a packet of seeds can turn an ordinary afternoon into a proper plant, play, grow adventure. But when to plant herb seeds in the UK is the bit that can make the difference between a tray of happy green shoots and a pot that stays stubbornly bare. Get the timing roughly right, though, and herbs are brilliantly forgiving little plants - perfect for first-time growers, curious children and anyone keen to add a fresh snip of flavour to tea, toast or tea-time tea.

When to Plant Herb Seeds in the UK

For most herb seeds, spring is the main sowing season. March to May is the sweet spot for starting many favourites indoors, while April to June works well for sowing tougher herbs outside once the weather has warmed up a little.

The exact month depends on the herb, where you are in the country and whether you are sowing on a warm windowsill, in a greenhouse or straight into a garden pot. A family in Cornwall may get going earlier than one in Northumberland, for example. Rather than racing the calendar, pay attention to light and temperature too.

Tender herbs such as basil dislike cold soil and frosty nights. Start them indoors in April or May, then move them outside after the risk of frost has passed - usually from late May onwards in much of the UK. Hardy herbs, including parsley, coriander, chives and dill, can often be sown earlier, from March, especially with a little shelter.

If you are using a grow box at home, a bright indoor spot gives young seeds a cosy head start. It is a nifty way to begin while the garden is still having one of its chilly, drizzly moments.

A month-by-month herb seed calendar

January and February: plan, don’t rush

It is tempting to start sowing as soon as Christmas decorations disappear, especially when everyone needs a cheerful project. Yet January and February have short days and cold windowsills, which can leave seedlings thin, floppy and disappointed.

Use these months to choose your herbs, check pots have drainage holes and decide where they will live. If you have a heated propagator or a genuinely warm, very bright indoor space, you can start a small batch of basil late in February. For most homes, waiting a few weeks gives better results and far less faff.

March: the growing fun begins

March is a lovely time to sow parsley, chives, coriander, dill and mint indoors. These are great choices for younger gardeners because the jobs are simple: fill the pot, sprinkle the seeds, cover lightly, water gently and pop in a plant marker. Then comes the daily detective work - who can spot the first tiny shoot?

Parsley can be slow to germinate, so do not panic if it takes two to four weeks to appear. Keep the compost moist, not soggy, and leave the pot somewhere bright. Coriander and dill tend to grow more quickly, which makes them wonderfully satisfying for impatient little gardeners.

April: prime time for most herbs

April is one of the best months for sowing herb seeds in the UK. Start basil, parsley, chives, coriander, dill and oregano indoors, using small pots or seed trays. If days are mild and your garden has a sheltered patch, you can also sow hardy herbs outside.

Basil is the star of the warm windowsill. It needs warmth to germinate and plenty of light once it has sprouted. Keep it indoors for now, away from cold glass at night. A kitchen windowsill is ideal, especially when the promise of homemade pesto is involved.

For outside sowing, wait until soil is workable and no longer waterlogged. Seeds do not need a huge garden bed to thrive. A roomy pot, trough or recycled container with drainage can be plenty.

May: sow, pot on and head outdoors

May is gardening gold dust. Most herbs can be sown now, and earlier seedlings may be ready for bigger pots. It is also a good time to start another small batch of coriander, dill or basil, so you do not end up with every plant ready to harvest at once.

After the last frost in your area, begin hardening off indoor-grown herbs before leaving them outside. This simply means helping them get used to outdoor life gradually. Put pots outside in a sheltered, shaded spot for a few hours at first, then increase the time over a week or so. Tender basil should stay indoors if nights are still cold.

June and July: keep the flavour coming

Do not pack away the seeds just because summer has arrived. June and July are excellent for repeat sowing coriander and dill every few weeks. This keeps fresh leaves coming and avoids the all-or-nothing harvest that happens when one big batch grows at once.

Basil can still be sown in early summer, provided it has warmth and a sunny place to grow. Chives, parsley and mint can also be started, although they may take a little longer in very hot, dry spells. Water in the morning or evening, and give the compost a proper soak rather than a tiny daily sprinkle.

August and September: make the most of warm soil

Early August can still work for fast-growing herbs, especially coriander and dill. Later in the month, focus on harvesting what you have and taking a few pots indoors before nights cool down. Basil is particularly dramatic about a chill, so bring it in when temperatures begin dipping.

September is a useful month for sowing parsley indoors for autumn leaves, provided you can give it good light. It will not race away, but a small indoor crop can be a cheerful treat as summer fades.

October to December: grow indoors or take a breather

Outdoor sowing is largely off the menu by autumn, but a bright windowsill can still support small pots of parsley, chives or coriander. Growth will be slower, so think of this as a low-key indoor project rather than a speedy harvest challenge.

If your windows are dark or chilly, waiting until spring is kinder to both seeds and gardeners. Use the quieter months to dry herbs, save recipes and make plans for next year’s pizza toppings, herb butter and minty drinks.

The herbs that suit beginners best

Some herbs are more straightforward than others, especially when you are growing with children. Chives are wonderfully reliable and their grassy leaves are easy to snip. Coriander grows quickly, although it can bolt - flower and set seed - in hot weather. Sow little and often for the best chance of leafy harvests.

Basil feels like a summer holiday in a pot, but it needs warmth and protection. Parsley takes patience at the start, then rewards you with lots of pickable leaves. Mint is enthusiastic to the point of mischief, so keep it in its own pot rather than planting it in a border where it may take over.

Rosemary, thyme and sage are delicious, but they are slower from seed and can be trickier for beginners. Buying a small plant is often the easier route if you want those herbs quickly. That is not cheating - it is simply choosing the right adventure for the season.

Three small things that make a big difference

Herb seeds do not need complicated kit, but they do need the basics. Use fresh seed compost or coir, sow at the depth shown on the packet and label every pot straight away. Tiny seedlings can look surprisingly alike, and guessing games are less fun when you accidentally harvest dill instead of parsley.

Light matters just as much as watering. A bright windowsill is better than a warm but gloomy corner. Turn pots every few days if they lean towards the light, and avoid placing them directly above a hot radiator, where compost dries out at turbo speed.

Finally, do not drown them. Water gently when the top of the compost feels dry, and make sure excess water can escape. Seeds need moisture to wake up, but soaked compost can rot them before they get their first chance to shine.

When can you start picking?

Most leafy herbs are ready for their first careful snip once they have several sets of true leaves and look sturdy enough to cope. With basil, pinch out the top pair of leaves just above a set of leaves below. This encourages a bushier plant rather than one tall, wobbly stem.

Pick little and often, never stripping a small plant bare. Let children be the official harvest team: clean scissors, a bowl for the leaves and a simple job afterwards, such as stirring chopped chives into soft cheese or scattering basil over a pizza. Growing food feels even more magical when it becomes a bite on the plate.

Start with a few pots this spring, celebrate every green shoot and remember that a missed watering or wonky seedling is part of the fun. The best herb garden is not the neatest one - it is the one that gets everyone outside, hands muddy and keen to grow another pot.