The 25 best self-seeding plants to save you time and money (2024)

June 10th, 2018
Posted In: Gardening know how

Self-seeding plants are the key to gardening on automatic. The less you do, the more they grow.

And they’re free. You buy one packet of seeds or one plant, and get a lifetime of exuberant flowers.

Sometimes self-seeders even arrive in your garden without you buying anything at all!

I counted over 25 different kinds of self-seeding plants when I originally wrote this post. Now, six years later, most of those self-seeders are still filling my garden with free, beautiful flowers.

Most of these grow in a wide range of zones and climates.

And because self-seeded plants have chosen where they want to grow, they need very little care. You won’t have to fertilise or water them. You probably won’t even have to stake them.

All you need to do is pull them out if they stray too far.

Do I actually ever plant anything?

I promise I do. But without self-seeders, my garden would be much less vibrant. And I would have to spend much more time and money on it.

This year, self seeding flowers mean that I haven’t had to buy or grow any extra annuals to fill gaps.

What exactly are self-seeding plants?

When looking at plants that spread in the garden, ask yourself ‘is this a self-seeder or a clump-former?’ Clump forming plants spread outwards from the original plant, but they stay broadly where you planted them.

A self-seeding plant is one which plants itself by dropping seed. If you’re lazy about dead-heading, then self-seeders will turn to seed and drop the seed on the ground.

It will often pop up in a completely different part of the garden from where you originally planted it.

That’s because the wind or birds may also carry the seed, so the new plants can pop up from a neighbour’s garden – or even from quite a distance. I had always wanted some borage and one day it appeared. It has now self-seeded around the base of a rose, covering those bare stems.

Some plants, such as day lilies, have all expanded from one or two tiny plants into huge clumps. But they don’t wander round the garden, establishing themselves wherever they see fit. So I don’t call them self-seeders.

Which plants self-seed in your garden can depend on your soil type as well as how good you are at weeding and dead-heading.

Do self-seeded flowers come back year after year?

It depends. I’ve found that some plants are very efficient self-seeders, but others perform less well.

And it varies from year to year. One year, I have lots of self-seeded amaranth. The next year, I often find just a few scraggly stalks of amaranth.

Aquilegias and eryngium are both defined as top self-seeders by Gardeners World, but I have planted one or two aquilegias. They have very gently self-seeded but I still only have a couple, and they’re near where I planted their parent plants. I wouldn’t call them a top self-seeding plant for my garden.

It’s the same for eryngium, which has also stayed where I planted it, without invading anywhere else.

We have clay soil, by the way, with some flint. And we roughly equate to a USDA hardiness zone of 9, with winters that rarely go more than a few degrees below freezing. However, our summers are not usually as hot as a USDA zone 9 – the average summer day’s temperature is rarely hotter than 25C/77F.

My very favourite self-seeder

Wild gladioli

One of our friends was born in this house in 1939. He remembers the wild gladioli in the garden when he was a very young boy. It’s likely that they were already well established by then as most gardening in the Second World War was growing for food.

Botanical artist Jane Elizabeth Giraud grew up in this house in Victorian times. And she painted wild gladioli.

So these wild gladioli have been in this garden for a hundred years or more. It’s their garden, more than it’s mine.

The best self-seeding flowers

Cerinthe major purpurescens (Honeywort)

After wild gladioli, my number two self-seeder is cerinthe. It’s an unusual looking plant, and people always ask ‘what’s that?’ But it’s no trouble at all.

Alliums ‘Purple Sensation’ and Christophii

These are the self-seeding plants I couldn’t do without. I find that both Allium ‘Purple Sensation’ and Allium Christophii self-seed vigorously. I originally bought 15 Purple Sensation about ten years ago, and now have around 50.

There was one Allium Christophii in this garden when we moved in 15 years ago. We now have around 80-100.

Poppies

The common poppy or Papaver rhoeas is brilliantly colourful and so charmingly simple.

Lychnis coronaria

Otherwise know as ‘rose campion’, this has cheery pink flowers and a nice grey felted foliage. Some of my lychnis has planted itself in a neat circle around a tree. It’s too close and isn’t particularly good for the tree, but I do admire the way it has synchronised itself.

Erigeron karvinskianus (Mexican daisies or ‘seaside daisies’)

I love seeing clouds of these growing out of walls and steps. Though I do have friends who don’t like them…you know who you are.

Foxgloves

Where would a summer garden be without foxgloves? Here is a photo of the back border, which is actually full of plants which I planted. Except for the foxgloves, who kindly decided that I needed a bit more vertical interest.

Coriander

This is a surprise entry for this section. You are supposed to be able to grow coriander as a herb in Britain, provided you plant it late enough in the year to stop it bolting.

I have never managed to get more than a handful or two of the coriander leaves for the kitchen, but it flowers and self-seeds so beautifully that I think it probably works better as a flower for me.

Self-seeders for foliage

My top self-seeders for foliage or greenery are:

Euphorbia oblongata

It’s unstoppable in its bid for world domination. Some of my other euphorbias, such as Euphorbia palustris, don’t self-seed or spread at all.

Alchemilla mollis

Lady’s mantle froths happily between pavers and pops up in beds. I have no idea where it came from. One day it wasn’t there, and then it was.

Smyrnium perfoliatum

This is another vibrant early summer green that looks after itself. I bought three plants from Great Dixter over ten years ago, and now have two huge clumps. It’s exceptionally long-lasting as a cut flower and disappears completely around the end of June.

Smyrniums are becoming invasive in some parts, so it’s worth checking whether it’s invasive where you are. Search ‘is smyrnium invasive in (insert your area)?’

Self-seeding edibles

You can eat both marigolds and nasturtiums. I have known komatsuma, red sorrel and spinach to self-seed and be good to eat, and also rocket.

Parsley

Definitely my top self-seeding herb. It took a good year to get established from seed, and I was initially disappointed by its growth. But in its second year, it took off around the garden, where it serves as foliage, garnish and an ingredient for parsley sauce.

Self-seeding companion plants

It’s helpful if self-seeders can be useful. Marigold and nasturtiums are both valuable in the veg patch, where they help deter pests.

Marigolds

People can be snooty about these, and I do often pull them out, but their smell repels greenfly and blackfly. They also attract hoverflies which live on blackfly, so they are generally a good thing.

Sculptural self-seeders

Sculptural plants are vital in any garden, and self-seeders can be wonderfully sculptural.

Angelica archangelica

It takes a couple of years to establish because it’s a biennial, but once it gets a cycle going, you’ll never have to give it another thought. Brilliant in May and June, collapses a bit after that, but you have to leave it or it won’t self-seed.

Crocosmia ‘Lucifer’

There was a patch of Crocosmia ‘Lucifer’ in this garden when we arrived fifteen years ago. It is now everywhere, but I do like it. Its seed-heads are wonderful, both in the vase and in the garden.

Verbena bonariensis

This doesn’t self-seed quite as vigorously as I’d like, so I occasionally have to re-plant it. But it seems to need very little attention, and wanders about the garden, occasionally planting itself in a pot. It is hardy to minus 12C/10F.

Sisyrinchium striatum (Pale yellow-eyed grass)

Sisyrinchium just appeared in the garden and it self-seeds readily. I think it adds some bright highlights to the border, but it can turn into a nuisance.

If it does, just pull it out. Most self-seeders are easy to pull out. And I always say that it’s easier to pull a plant out than it is to plant it.

The best self-seeding plants for shade

Angelica archangelica, foxgloves, smyrnium perfoliatum, lamium (dead nettle), primroses and Solomon’s seal all do well in shade. Solomon’s seal takes several years to get properly established, but I know have two generous clumps – from just one or two plants.

When NOT to allow self-seeding

Some plants do not make good self-seeders. In the veg bed, you won’t get any reasonable flavour out of anything that has self-sown from an F1 hybrid. That’s because an F1 hybrid has been specially created. Its seeds are usually disappointing.

However, heritage varieties of vegetable may self-seed, or it’s worth keeping their seed.

Similarly some garden flowers don’t come true from seed. My lavender self-seeds but I have been warned by the grower I bought it off that it won’t come true. He advised me to take cuttings rather than rely on self-seeders.

It’s also important to know what is invasive in your area. By ‘invasive’, I mean on an official list of plants that could do damage to your countryside if they escape into the wild. If plants grow too well in a particular climate or countryside, they can out-compete the local plants. And that means that local wildlife may not have sufficient habitat or food. This can be very expensive and difficult to clear up.

Every government has a listed of invasive plants. It’s usually illegal to sell or plant them in your area – yet the very same plants can be lovely garden plants in a different country or area.

So do an online search for ‘is (insert plant name) invasive in (insert your area or country)? Look for official government or university lists.

The one care tip you do need for self-seeders…

If you are an expert gardener, you can tell the difference between self-seeding plants you want and weeds at a fairly early stage. However, I’ve accepted that allowing such a vibrant mix of self-seeders means I also have more work with weeding, as the weeds do seem to get established early too. In this post, I’ve covered this issue with finding the balance between self-seeding vs weeds.

How and when you mulch can also affect which plants self-seed and how vigorously. Adding a layer of well rotted manure, garden compost or a wood chip mulch helps prevent weeds. It also breaks down to add nutrition to the soil.

However, anything that stops weeds will also stop self-seeders. I don’t find that mulching stops all self seeders, but it does stop some.

There are also lots of self-seeders in a wildflower meadow. Even if you only have a small patch of lawn, this post can help you create a mini meadow.

And read these posts if you want to save more money on your gardening or save money on garden design!

Shop my favourite gardening tools, books and products…

I’m often asked for recommendations, so I’ve put together lists of my favourite books, tools and gardening products on The Middlesized Garden Amazon store (Links to Amazon are affiliate, see disclosure).

For example, if you’re interested in self-seeding plants, you may also be thinking about making your garden more wildlife-friendly. I’ve done a post on What Makes A Good Wildlife Garden, and also put together some useful wildlife-friendly products like bird feeders, hedgehog homes and more on the Middlesized Garden’s Wildlife Friendly shopping list.

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