GARDENING: Sow in September to make hardy annuals last longer

Ammi majus is a perfect foil for other flowers.
Ammi majus is a perfect foil for other flowers.

Most people sow hardy annuals in spring, but you’ll get a much earlier display if you sow seeds in early autumn.

Combine September sowing – when there’s warmth in the soil – with the usual March-May timescale and your annuals will look better for far longer.

Calendula Nova ' English or pot marigold.

Calendula Nova ' English or pot marigold.

Not every type is suitable – they must tolerate frost, so it’s not suitable for half-hardy annuals.

There’s three basic methods; direct sowing without protection; direct sowing with cloches or horticultural fleece when frosty; or sow in pots and keep frost-free over winter in a cold greenhouse/coldframe.

For direct sowing, either broadcast seeds thinly over weed-free, firmed and raked soil, or sow in drills.

Don’t use fertiliser at this point.

Godetia Lady in Blue behind perennial sweet pea.

Godetia Lady in Blue behind perennial sweet pea.

Aim for a gap of about 0.5cm (¼in) between seeds, then cover lightly with soil and water. If sowing in drills, space them 15-45cm (6-18in) apart.

If you live in a particularly exposed place, sow annuals under cover at 18°C (64°F), reducing to 15°C (59°F) after germination.

Grow them on into small plants, harden them off for overwintering in a cold frame or cold glasshouse, to plant out the following spring.

These hardy annuals probably will require protection in a bad winter.

If hard frosts are forecast, protect with cloches or horticultural fleece.

• Ammi majus/Ammi Visnaga;

• Calendula officinalis (pot marigold);

• Centaurea cyanus (cornflower);

• Limnanthes douglasii (poached egg plant);

• Linum grandiflorum (flax);

• Hordeum jubatum (squirrel tail grass);

• Nigella damascena (love-in-a-mist);

• Papaver commutatum, P. rhoeas, P. somniferum (corn and opium poppies);

• Briza (quaking grass); Consolida (larkspur);

• Agrostemma githago (corncockle); Bupleurum;

• Iberis (annual candytuft);

• Scabiosa (scabious, a perennial often grown as an annual);

• Phacelia tanacetifolia (lacy phacelia);

• Malope trifida.

These plants definitely need some protection from frosts.

Sow in pots under glass and overwinter in a cold frame/cold greenhouse.

• Eschscholzia (Californian poppy);

• Gypsophila elegans;

• Lavatera trimestris (mallow);

• Cerinthe major var. purpurascens;

• Salvia viridis (annual clary);

• Matthiola longipetala subsp. bicornis (night-scented stock);

• Orlaya grandiflora;

• Nemophila;

• Adonis aestivalis;

• Godetia.

Sweet peas can also be autumn sown.

• For more gardening tips and advice, visit Mandy’s website,