the best summer annual flowers

Annuals are the best plants in the world – better than trees, better than shrubs, better than perennials, even better than biennials, which are hard to beat. They flower, set seed and make babies as quickly as they can, trying to colonise ever more ground. Give them a bit of open soil – a good seed bed – and they're away, the flamboyant, make-it-happen-now, pre-credit-crunch flowers. They don't know anything about long-term saving habits or prudence. If flowers can be racy, annuals are the Regency bucks, Byron in love, crash-and-burn addicts, the most beautiful specialists in the spend, spend, spend lifestyle. Gardens would be dull without them.

Annuals form two groups: hardy – which can take some frost; and half-hardy, which can't and need more TLC. Within both groups, they divide again into the straight-up, showy flowers, the true parading bucks – things like  sunflowers, cosmos, zinnias and snapdragons – and the quieter things, the foliage-flowers, which form the backdrop and foil, the rice to balance the curry of the strong, flamboyant crew.

Natural show-offs

Start with the Byrons. Grow Asclepias curassavica 'Golden Fortune' (in fact a tender perennial, usually grown as an annual), which has been flowering since June in my greenhouse. It's now moved outside, planted with the dark crimson, striped pink Canna 'Durban' and looks magnificent; a pair of tropical, parrot-looking plants with a similar feel. If the seed is sown fresh, the ascelpias is easy to grow and will be in flower within 15 weeks of a late winter sowing. If you have a greenhouse, you can then dig up your plants and bring them inside and they flower right through the summer and autumn the following year as well, a good five months last year in my garden and then greenhouse.

I'm always on the lookout for new varieties of three stalwart families – the cosmos, zinnias and rudbeckias, which flower longer and harder than almost any other annuals. There are a lot of boring egg-yolk and primrose-yellow rudbeckias, with a rather dried-up feel about them, but recently a good swathe of darker, richer-coloured varieties have emerged such as 'Cappuccino' and 'Mocca'. These are so much classier and more interesting than the yellows, yet they flower just as long – from July until November.

With cosmos you can rarely go wrong. Good old C. bipinnatus 'Purity' and 'Dazzler' are plants I would take to my desert island to cheer me along, and this year, I've added 'Antiquity'. This is a smaller form – but not too small – ideal for growing in containers and has flowers with the most beautiful mix of colours, from rich carmine to a faded tapestry equivalent. Each flower is as good going over as it is when it first emerges from bud.

Zinniasare the other must-have annual for the passionate lover of zing and these come in almost every colour, shape and size. For a lush and exuberant group in the cutting garden, we've got Zinnia elegans 'Giant Purple', the goliath of the family, planted with an almost matching colour, Cleome 'Violet Queen' and darker, red-carmine, Cosmos 'Dazzler'. A smaller version of this combination was such a success last summer, we've tripled the size of the group this year.

Chorus line players

Enough of flowery flowers and on to the rice brigade. I think most tobacco plants (all except the handsome and statuesque Nicotiana sylvestris and N. tabacum) are best used in this flower-foliage way, to form the gently rolling plateaus below and behind strong, showy things. Use the green-flowered, Nicotiana alata 'Lime Green' and a couple of newer varieties, 'Hopleys' (with elegant, mini Shakespearean purse-like flowers) and 'Tinkerbell' (green and browny crimson) to form the perfect foil – the calm – to a late-summer bonanza of dahlias and zinnias.

Nicotiana alata 'Grandiflora' is another good one, pale creamy white, particularly useful in partial shade. Planted in a bright, hot spot, its flowers flop completely in the heat of the day, but this tobacco looks and smells delicious with a bit of sun protection. We've also trialled a couple of new dark, rich-coloured tobacco plants this year, 'Perfume Purple' and 'Perfume Red'. I love them both, but the purple looks exhausted at midday, if lovely again by five, whereas 'Perfume Red' stands perky and strong through both night and day.

Outstanding among the background annuals are the umbellifers. Ammi majus and Orlaya Grandiflora – with its mini handkerchiefs attached to every bloom – are both unmissable, good in drifts as large as you can allow them, and lovely as a smaller, light and airy background to more substantial flowers.

I would now add the less well-known Ammi visnaga. I've had this ammi in my garden for the first time this year, interplanted with blue, violet and white larkspur, a great success, undulating cumulus nimbus white and green clouds with shafts of larkspur colour slashed through. The chunkier A. visnaga has better leaves than A. majus – delicate and ferny, like fennel and it seems to flower happily for almost twice as long.

Most of these annuals are half-hardy and so need to be sown next spring, but these two ammis and orlaya are best sown from the end of August until mid September. Sown in the next month, they get their roots down and settle in before the soil loses its warmth. Underground, they continue to grow gently outside all winter, and will form impressive plants, almost twice the size of those sown in the spring.

Browse our range of half-hardy and hardy annual seeds or our range of half-hardy and hardy annual plants and seedlings.