Sowing hardy annuals in autumn

I love sowing seeds at this time of year. As everything else is slowing down and dying back, you can focus on coaxing a handful of seeds into life and nurturing them as autumn turns into winter. It will also give you a head start in spring, as you’ll have bigger, stronger plants a few weeks earlier than if you sowed them in spring. You can sow any time between the beginning of September and the first week or two of October before it gets too cold, either directly into the ground or in seed trays. If it’s the latter, then you’ll need a cold frame or cold greenhouse to overwinter them. These are hardy plants, but in pots or trays they will need protection from wind and rain, and from slugs and other pests. Sow into good seed compost that has been pre-watered, and keep the seedlings well-watered as they grow in autumn, reducing the watering as it gets colder. In spring, up the watering again and plant them out in the garden in early spring as soon as the ground is workable. Photos by Sabina Rüber.

Ammi majus

Centaurea cyanus ‘Black Ball’

Calendula ‘Touch of Red Buff’

What you can sow now

Ammi: Ammi majus is possibly the most useful annual I grow. Like a refined cow parsley, it has lacy white flowers that pad out a border, linking other plants together and bringing that ever-popular naturalistic feel to the garden. It is very easy to grow from seed and can be sown both in autumn or in early spring - possibly more than any other hardy annual it is worth sowing this in autumn as the plants tend to be bigger, stronger, and flower earlier than those sown in the spring. I sow them into modular seed trays, two seeds to a cell, and pot them on later in the autumn, before planting them out in early spring, filling gaps in the border.

Calendula: marigolds are brilliantly easy to grow from seed, and you can either sow them direct or if you want more control, in seed trays. Their little sea-horse-like seeds are easy to handle and can be sown one or two to a cell in a modular seed tray. The classic bright orange marigold is great for edging vegetable beds, making an excellent companion plant, while other varieties like ‘Orange Flash’ and ‘Touch of Red Buff’ are more subtle and blend into a more formal border.

Cornflowers: cornflowers (Centaurea cyanus) are easy to grow and make lovely cut flowers that should appear by mid-May with an autumn sowing. Sow the seeds direct and thin the seedlings to leave gaps of about 20cm between them. For the true cornflower blue grow the cultivar ‘Blue Boy’, or for purple sophistication, try ‘Black Ball’.

Consolida ajacis ‘Misty Lavender’

Nigella papillosa ‘African Bride’

Orlaya grandiflora

Larkspur: these annual delphiniums can be tricky to grow from seed. They don’t need heat to germinate, and indeed can benefit from a week or so of cold in the fridge before sowing. They can either be sown direct into the ground in September, or in modular seed trays so you can keep control. Plant them out in late winter as soon as the soil is workable, at the same time making another spring sowing for a succession of flowers. My favourite variety over the past few years has been Consolida ajacis ‘Misty Lavender’ which has dusky lavender-pink flowers.

Nigella: Love-in-a-mist (Nigella damascena) is another one to sow direct in autumn. Once you have sown it for the first time, you can then collect seed from your existing plants at the end of the summer and scatter it round the garden where you want it to pop up the following year. Other types such as the lovely Nigella papillosa ‘African Bride’ are just as easy to grow.

Orlaya: I have always found Orlaya grandiflora tricky to grow as germination can be sporadic, but others find it easier than ammi so every year I persevere! It is an umbelliferous plant like ammi, smaller in stature but with more substantial flowers - truly lovely woven in with emerging perennials and other annuals. I think it’s best sown in the autumn. Sow the seeds in modular seed trays and grow them as you would grow ammi, potting them on if necessary before planting out in early spring.

Papaver rhoeas ‘Amazing Grey’

Papaver somniferum ‘Black Peony’

Papaver somniferum ‘Lauren’s Grape’

Poppies: opium poppies (Papaver somniferum), field poppies (Papaver rhoeas) and Californian poppies (Eschscholzia californica) are better sown direct. Scatter seed where you want it to flower, weaving them in and out of other plants, keeping half back so you can sow more in spring. I have a dark pink opium poppy that I collect seed from each year and use it for padding out new or cleared borders. I have also grown Papaver rhoeas ‘Amazing Grey’ for the past two years, which has flowers of the most extraordinary dusky grey-purple.

Sweet peas: you can sow sweet peas slightly later than the other annuals mentioned here as they grow quickly, and you don’t want them to peak too early. I usually sow them in October or even November, germinating them indoors and then moving them quickly out to the unheated greenhouse.

To read more about all these annuals, click here, or have a look at my book The Flower Garden. I also sell wooden seed trays and pot tampers in my shop.