Late summer has a particular feeling in the garden.
The exuberance of June has softened. Flowers are fading, grasses are turning gold and seed heads are appearing where only a few weeks ago there were petals.
It can be tempting to reach immediately for the secateurs.
Don’t be too quick.
Those dry pods, rattling capsules and fading flower heads contain next year’s garden.
Saving seeds from your own plants is one of the simplest and most satisfying gardening jobs of late summer and autumn. It costs almost nothing, gives you plants to grow or share the following year and encourages you to notice a part of the plant’s life cycle that is easily overlooked.
There is something rather wonderful about it too.
A handful of tiny brown seeds gathered on an August afternoon may become next summer’s sunflowers, sweet peas and cosmos.
All you really need is a paper bag, a pencil and enough restraint not to tidy everything away.
Why save your own seeds?
The practical answer is simple.
Free plants.
A single seed head can sometimes contain enough seed to produce dozens of plants, making seed saving an inexpensive way to fill gaps, increase favourite plants and have something to swap with friends and neighbours.
But there is another reason to do it.
Saving seed completes the gardening year.
We spend spring sowing, summer tending and autumn clearing away. Collecting seed joins one season to the next.
Instead of starting again with a packet from the garden centre, you’re beginning with something that grew in your own soil.
There is a pleasing continuity to that.
And once you’ve successfully grown a plant from seed you collected yourself, you’ll find it remarkably difficult to walk past a dry seed head without investigating.
When is the best time to collect seeds?
There isn’t one particular weekend when the entire garden becomes ready for seed collecting.
Different plants ripen at different times.
In Britain, the main seed-collecting season stretches broadly from summer into autumn, with plenty to gather during August and September.
The plant itself is a better guide than the calendar.
Watch seed heads and pods carefully as flowers fade.
Many change from green to brown, black or another mature colour as they ripen. Pods become dry and papery. Capsules begin to split. Seeds inside become firm and fully developed.
The trick is to collect them when they’re ripe but before the plant disperses them itself.
This can require a little vigilance.
Wait too long and the garden may have completed the job without you.
Poppies scatter their seeds.
Sweet-pea pods split.
Wind carries away lighter seeds.
Birds regard certain seed heads as an invitation to lunch.
The gardener is not the only creature interested in the harvest.
Choose a dry day
For most dry seeds, choose a dry, still day once any dew or rain has disappeared.
This makes the seeds easier to handle and reduces the amount of moisture you bring indoors with them.
You don’t need to collect specifically in the morning. The important thing is that the plant material is dry.
Take paper bags or envelopes into the garden and label them before or immediately after collecting.
Do not trust yourself to remember later.
Six envelopes containing mysterious brown seeds are considerably less informative in February than they seemed in August.
Which plants should you collect seed from?
Start with healthy, vigorous plants that performed well in your garden.
Perhaps one cosmos flowered particularly freely.
Maybe a sunflower had an especially beautiful colour.
Perhaps a lettuce cropped well before bolting.
Saving seed from good plants allows you to carry something of that garden season forward.
However, there is an important complication.
Plants grown from saved seed won’t necessarily look exactly like their parents.
That’s part of the fascination of seed saving.
And occasionally part of the surprise.
Will saved seeds come true to type?
Sometimes.
But not always.
Species plants are generally more likely to produce recognisably similar offspring. Cultivated varieties can be less predictable, particularly if they’ve cross-pollinated with related plants nearby.
And seed collected from F1 hybrids is especially unlikely to produce plants identical to the parent.
If you still have the original seed packet, look for “F1” after the cultivar name.
You can certainly sow seed collected from an F1 plant.
Just don’t expect an exact repeat performance.
The resulting plants may differ in height, colour, vigour, flavour or other characteristics.
Which can be disappointing if you wanted precisely the same tomato.
Rather exciting if you enjoy surprises.
Cross-pollination can produce surprises too
Even non-F1 plants can produce variable offspring if pollen has arrived from another compatible plant.
This is particularly relevant when saving vegetable seeds.
Pumpkins and courgettes, for example, can cross with compatible plants, meaning seeds saved from their fruits may produce something rather different the following year.
Some flowers will cross readily too.
If maintaining a particular cultivar is important, seed saving becomes a more technical business involving isolation distances, controlled pollination and careful selection.
For ordinary garden seed saving, you don’t necessarily need to worry about all that.
Sow the seeds.
See what happens.
Gardening could occasionally do with a little mystery.
How to collect seeds from the garden
For most flowering plants and vegetables, seed collecting is wonderfully straightforward.
Step 1: Wait for the seed to ripen
Allow flowers to fade naturally and watch what develops behind them.
Depending on the plant, this might be a pod, capsule, dry flower head or cluster of seeds.
Don’t deadhead every flower if you’re planning to collect seed.
Choose a few good blooms and leave them alone.
Step 2: Collect the seed heads
Once they’re ripe, cut the seed heads or pods carefully and place them into a labelled paper bag or envelope.
Paper is useful because it allows moisture to escape.
Avoid putting freshly collected seed heads into sealed plastic bags, where trapped moisture can encourage mould.
For plants inclined to scatter their seeds, hold the bag underneath the seed head before cutting.
It saves a surprising amount of crawling around beneath the flower bed afterwards.
Step 3: Let everything dry
Bring the collected material somewhere warm, dry and well ventilated.
Spread it over paper, place it on trays or leave loosely filled paper bags open so air can circulate.
The RHS suggests that around a week to ten days is a useful guide for drying many collected seed heads before extracting and storing the seed.
Don’t put them in strong direct sunlight or somewhere damp.
Patience is important here.
Seed stored while still moist is much more likely to develop mould.
Step 4: Separate the seed
Once thoroughly dry, break apart the seed heads or pods.
Shake, rub or gently crush them as appropriate to release the seeds.
Remove as much unwanted plant material – often called chaff – as reasonably possible.
You don’t need laboratory standards.
A few tiny fragments of dry flower head aren’t going to bring civilisation to an end.
Step 5: Label immediately
Write down at least:
- the plant name
- the cultivar, if known
- the year collected
You might also record the colour or where it grew.
“Tall pink cosmos by shed, 2026” may prove considerably more useful next spring than “COSMOS???”
Gardeners have been defeated by their own handwriting before.
Don’t join them.
10 easy plants to save seeds from
If you’re new to seed collecting, begin with plants that make the process fairly obvious.
These ten are excellent candidates for developing the habit.
1. Sunflowers
Sunflowers make seed saving wonderfully visible.
As the flower fades, the centre develops into a great plate of seeds.
Leave the head on the plant to mature for as long as conditions allow. Once the back of the flower head has matured and the seeds are plump, collect it and allow it to finish drying somewhere protected if necessary.
Birds also adore sunflower seeds.
If they’re getting there before you, cover selected developing heads with a breathable mesh or paper covering that still allows good airflow.
Do leave some seeds for the birds if you can.
They have, after all, been watching them for weeks.
2. Cosmos
Cosmos is one of the easiest annual flowers to grow from collected seed.
After the petals fall, elongated dark seeds develop in the centre of the flower.
Watch them carefully.
Once ripe, they detach easily, which is useful for the plant and mildly inconvenient for the gardener.
Collect dry seed heads regularly and place them in a labelled paper envelope.
A few cosmos plants can provide more than enough seed for next year’s display.
And probably the year after that.
And possibly several neighbours.
3. Sweet peas
If you want sweet-pea seeds, stop deadheading a few flowers towards the end of the season and allow pods to develop.
Let the pods mature and dry on the plant as far as conditions allow.
Collect them before they split naturally and scatter the seeds.
Sweet peas are largely self-pollinating, so they’re a relatively approachable choice for home seed savers, although variations can still occur.
Store the thoroughly dried seeds somewhere cool and dry until sowing time.
One important distinction: ornamental sweet peas are not edible.
Their resemblance to edible peas does not make them dinner.
4. Nasturtiums
Nasturtium seeds are delightfully difficult to miss.
Large, pale green seeds form after the flowers fade and often fall to the ground as they mature.
Collect them when well developed and allow them to dry thoroughly before storage.
Nasturtiums are generous plants and may also self-seed around the garden without any assistance.
In other words, while you’re carefully labelling envelopes, the nasturtium may already have made alternative arrangements.
5. Calendula
Calendula – often called pot marigold – produces wonderfully distinctive curved seeds.
Leave some flowers to fade and watch the seed heads develop.
Unlike many plants whose seed heads are always collected completely brown and brittle, calendula can sometimes be gathered while the seed is still relatively green but well developed.
Dry it thoroughly afterwards before storing.
Calendula is another enthusiastic self-seeder, so you can also leave some heads untouched and allow the plant to decide where next year’s flowers should appear.
Its opinion on the matter may differ from yours.
6. Marigolds
Garden marigolds (Tagetes) produce masses of slender seeds within their faded flower heads.
Allow selected flowers to dry well, then remove the heads and pull them apart over a sheet of paper.
Inside you’ll find long, narrow seeds, often dark at one end and pale at the other.
Let them dry thoroughly before putting them away.
If you’ve grown hybrid marigolds, remember that their offspring may differ from the parent plants.
Consider it less a guarantee and more an experiment.
7. Love-in-a-mist
Few plants package their seeds quite as beautifully as love-in-a-mist (Nigella damascena).
After the delicate flowers disappear, inflated ornamental seed capsules take their place.
They’re almost too attractive to cut.
Leave them until they’re dry and papery, then collect the capsules before they split and shake out the dark seeds.
Alternatively, leave a few standing.
Nigella is perfectly capable of sowing itself and appearing next year in places you hadn’t considered.
Often these are better places.
Try not to take it personally.
8. Poppies
Poppy seed heads are one of the great pleasures of the late-summer garden.
Once the petals fall, the sculptural capsules remain.
As they mature and dry, small openings develop beneath the top of many poppy capsules, allowing seeds to shake out.
At this stage, the seed head behaves rather like a botanical pepper pot.
Cut mature heads carefully over a paper bag and tip out the tiny seeds.
Save some and allow others to scatter naturally.
There is room for both organisation and chaos in a good garden.
9. Lettuce
Saving lettuce seed requires a little more patience because you have to deliberately not eat the lettuce.
Choose a healthy plant and allow it to bolt.
It will grow surprisingly tall, produce flowers and eventually develop fluffy seed heads.
Once mature, collect the seed carefully on a dry day.
Lettuce is largely self-pollinating, which makes it one of the more approachable vegetables for beginner seed savers.
The hardest part is accepting that something which began as lunch is now several feet tall.
10. Radishes
Radishes are another crop that needs to be left well beyond its normal harvesting stage.
Instead of pulling the root, allow a healthy plant to flower.
It will eventually produce seed pods.
Leave these to mature and dry, then collect the pods and open them to reveal the seeds inside.
This is also a lovely way to see the complete life cycle of a vegetable we normally remove from the ground after only a few weeks.
A radish has ambitions beyond salad.
We simply don’t usually give it the opportunity.
What about tomato seeds?
Tomatoes deserve a separate mention because they’re often recommended for beginner seed saving.
They’re certainly worth trying, particularly with non-F1 cultivars, but the preparation differs from collecting dry flower seeds.
Tomato seeds are surrounded by a gelatinous coating inside the fruit.
Gardeners commonly use a fermentation process to clean tomato seed before drying and storing it.
If you want to save tomato seeds, follow a method specifically intended for tomatoes rather than applying the dry-seed technique above.
And once again, check whether your tomato is an F1 hybrid before expecting identical offspring.
How to store saved seeds
Once seed is completely dry and cleaned, place it in clearly labelled paper packets.
These can then be kept together inside a suitable airtight container somewhere cool, dry and dark.
Keeping seeds cool and dry slows deterioration and helps preserve viability.
Some gardeners keep carefully dried seed in the refrigerator, although protection from moisture is essential.
For ordinary home seed saving, a reliably cool, dry storage place may be perfectly adequate for many common garden seeds.
Whatever system you choose, organisation helps enormously.
An old biscuit tin filled with neatly labelled seed packets is perfectly respectable.
Possibly superior to the original purpose of the biscuit tin.
Don’t assume every seed lasts the same length of time
Seed longevity varies enormously between species and according to storage conditions.
Some remain viable for years.
Others lose viability much more quickly.
Rather than relying on a universal “three-year” or “five-year” rule, label everything with the collection year and check species-specific guidance if you’re keeping seed for a long time.
For favourite plants, sowing relatively fresh seed is often the simplest approach.
How to test whether old seeds will germinate
Found an envelope of seeds at the back of the cupboard and can’t remember whether they’re still viable?
Try a simple germination test.
Place a known number of seeds – ten makes the arithmetic pleasantly easy – on damp kitchen paper.
Keep them under suitable germination conditions for that particular plant and monitor how many sprout.
If eight out of ten germinate, you have roughly an 80 per cent germination rate.
If two struggle into life after considerable encouragement, sow rather more generously.
And if nothing happens at all, you have gained an empty envelope.
Which is still useful.
Watch out for mould
Moisture is one of the great enemies of stored seed.
If seeds are put away before they’re properly dry, mould can develop and ruin the collection.
That’s why the drying stage matters.
If you discover mouldy seed later, don’t simply mix it with the rest and hope for the best.
Discard affected material and inspect nearby packets.
A little extra drying time in autumn is much less disappointing than opening a treasured packet in spring to discover a small biological experiment inside.
Leave some seeds for wildlife
Not every seed head needs to go into an envelope.
In fact, please leave some outside.
Seed heads can provide valuable food for birds, while hollow stems and standing vegetation offer shelter for insects through autumn and winter.
Sunflowers are particularly popular with seed-eating birds, but many other plants contribute too.
This creates a pleasant compromise.
Collect enough for next year’s garden.
Leave enough for this year’s wildlife.
Everybody gets a share.
Share your seeds
One of the nicest things about collecting seed is that you very quickly acquire too much of it.
This is not a problem.
It is an opportunity.
Swap packets with friends, neighbours or fellow gardeners.
Pass a handful of seeds from a particularly lovely plant to someone else.
A flower grown in one garden can then appear in another the following year.
Seed has travelled between gardeners like this for generations.
Plants come with stories.
“This came from my neighbour’s garden” is a much more interesting history than “aisle seven”.
Start with a few favourites
There is no need to turn your spare room into a seed bank during your first autumn.
Choose three or four plants.
Perhaps a sunflower you particularly liked.
A favourite cosmos.
Some sweet peas.
A handful of poppy seeds.
Collect them when they’re ready, dry them carefully and write their names on the packets.
Then put them somewhere safe.
Preferably somewhere you’ll actually remember.
Next spring, take them out and sow them.
Some may produce plants exactly as you remember.
Others may surprise you.
A few may refuse to appear altogether.
That’s part of the pleasure.
Seed saving isn’t about achieving perfect control over the garden.
It’s about carrying something forward.
One summer quietly tucked inside an envelope, waiting for the next.
Further Reading: My Garden Journal & Notes
