Hardy annuals

THE kitchen garden at Harlow Carr includes flowers for cutting, and it’s a rewarding crop to grow, as well as looking decorative among the vegetables. Selecting plants that flower for a long time and produce more flowers the more you cut, for example sweetpeas, makes sense.

The most prolific flowerers are hardy and half-hardy annuals, biennials and dahlias.

Hardy annuals in particular are easy to grow from seed. They can be quite inexpensive to buy and they include many colourful and attractive flowers.

Annuals are plants that grow from seed, flower and die within a year; hardy annuals are able to withstand winter cold, and some degree of frost (half-hardy or tender annuals need protecting). Most are sown direct into the soil, avoiding having to grow in modules and the need for a greenhouse, and they are very productive with the added bonus that many self-seed after flowering.

One area in the kitchen garden is entirely self-seeded annuals, a mixture of calendulas, cerinthe, bupleurum and nigella, and it looks very pretty.

Having a separate area to grow annuals makes it easier to replant or sow, as well as make soil improvements; a sunny area sheltered from the wind with well-drained soil, not too rich in nutrients, is the ideal.

You can also grow smaller cutting flowers in pots and window boxes, such as marigolds, cerinthe and dwarf sweetpeas.

It’s important to avoid sowing direct too early by watching for signs of growth in the garden – weeds and other seedlings. That’s probably around the second half of April for here. As with any seed sowing, soil needs to be properly prepared — reasonably fine, no large lumps, with compost/organic matter (and grit if soil is heavy) added previously and allowed to settle in. To get rid of weed seeds, cover soil with plastic to force weed seedlings to germinate then hoe them off. Some plants prefer a poorer soil, such as dill, cerinthe, bupleurum and California poppies.

Seed can be sown in rows or broadcast — sowing in rows makes it easier to recognise seedlings. Sow thinly and not too deep, rake soil over gently and tamp down. Water with a fine rose as seedlings emerge.

Thin out the seedlings, then transplant larger plants to their final places with 25-30cm between plants, more for larger subjects. Staking with pea sticks, netting or canes is really important; broken or bent stems are useless for flower arranging, and don’t look great in the garden either.

Hardy annuals can be sown in either autumn or spring. Autumn sowing makes for larger plants that grow away earlier in spring, though may need some protection over a harsh winter. Spring-sown plants have less well-developed roots but will still make good plants if conditions are right.

Ammi majus, bupleurum, cornflowers, California poppies and nigella can be sown in autumn, dill and sunflowers do best in spring and Cerinthe and pot marigolds are fine at either.

Some favourite hardy annuals I wouldn’t be without include Ammi majus with its delicate foliage and umbellifer flowers, dill — again lovely foliage but great seedheads, bupleurum rotundifolium ‘Décor’ — limegreen, delicate, good flower and seedheads, cerinthe major ‘Purpurescans’ – the blue honeywort (this needs warmth to germinate, prefers a well-drained soil, and produces lots of seed). I love the way pot marigolds seed themselves and cross to create new flowers, but there are also some great varieties, eg ‘Indian Prince’ and ‘Touch of Red’. Centaurea cyanus (cornflower) is easy from seed – use pea sticks to support the plants.

Sunflowers — Helianthus annuus — are susceptible to rotting in our heavy soil as well as slug attack, so are grown in pots in spring then planted out when they are a bit larger.

There are lovely dwarf types, e.g. Irish Eyes, Little Dorrit, but you definitely need to stake the tall ones well. Sweetpeas need a whole article to themselves, but briefly ours are sown in pots in autumn, overwintered in coldframes then planted out in April.