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Hardy annuals

Splashes of colour for beginners and kids

Hardy annuals are the go-to plants for beginners, children, those on a budget, or if you want a quick border of container filler.

You need next to no equipment or knowledge – what’s not to love?

Sowing can begin from late March to May as the soil begins to warm up (if weed seedlings are around, you should be OK).

If you have a heavy clay soil and live in the North, use your common sense – an old farmers’ test was to sit their bare backsides on the soil – if it was comfortable, they would begin sowing. If it’s wet and cold, don’t sow and tell your arresting officer it’s my fault.

To sow directly into soil outdoors, weed the area, level the soil with a rake and tread lightly to flatten it.

Either scatter seeds over the surface or make drills (shallow grooves) to sow them into. Follow the directions on your seed packets for the best time to sow and depth for planting. The spacing between drills depends on the eventual size of the plants.

Once plants are growing strongly, keep down weeds by hand and water in dry weather. Keep deadheading to prolong flowering.

If you have really cold soil, you can sow hardy annuals in modules under glass in multi-purpose compost, but you’ll then have to harden them off like half-hardy annuals before planting out.


Potted guide: autumn sowing hardy annuals

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

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

Not every type is suitable – they must tolerate frost. Also, remember there is an element of risk here – plants can and do, fall victim to pests, diseases, and very wet/cold weather.

There are three basic methods:

  • Direct sowing without protection;
  • Direct sowing with cloches or horticultural fleece when frost;
  • Sow in pots and keep frost-free over winter in a cold greenhouse or cold frame. (I’d give them all protection in the North.)

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.  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 cold or exposed part of the country, 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.


Suitable varieties

Ammi majus
Ammi majus

These hardy annuals probably will require protection in the North, or even in southern areas if there’s 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);
  • Helianthus (annual sunflower);
  • Consolida (larkspur); Agrostemma githago (corncockle);
  • Bupleurum;
  • Iberis (annual candytuft);
  • Scabiosa (scabious, a perennial often grown as an annual);
  • Phacelia tanacetifolia (lacy phacelia);
  • Malope trifida.

Plants needing protection

Early Californian poppies
Early Californian poppies that have decided to live as perennials

These plants need some protection from frosts. Cloches and horticultural fleece should be sufficient in the south, sow in pots under glass in the north.

  • Eschscholzia (Californian poppy – although I have a self-sown plant which is ‘perennial’);
  • 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.