Sowing flowers in late summer

Posted in All Gardening Advice, Annuals, August, September, on

I am a believer in late summer sowing – getting most of my hardy annuals into the ground as soon as I can. The soil is warm in late August, and with a little rain the top few inches of ground should be good and moist.

These are ideal conditions for quick germination, so with many things – corn poppiesAmmi majus (Bishops flower), Orlaya grandiflora (watch out for carrot fly on this later – it may need protection to flower long and hard in June and July), cornflowers, both black and blue Centaurea Cyanus ('Blue Boy' and 'Black Ball'), the annual scabious (Scabiosa 'Tall Double Mix'), my favourite euphorbia for picking, Euphorbia oblongata, as well as Salvia viridis 'Blue', sowing in the next couple of weeks is the ideal time.

With all these invaluable garden flowers – which will fill your garden with an ethereal, Tilda-Swinton-type beauty – sowing now makes for bigger, more flowery plants than if you sow in the spring. The roots develop through the autumn, when growing life is easy, and should penetrate to a depth in the soil where moisture levels and temperatures remain pretty constant.

The seedlings can then grow slowly through winter to create a huge food and drink reservoir for quick growth when light levels and soil temperatures warm again in the spring.

Even in 2009, when temperatures fell to 14°F (-10°C) for several nights on the trot, almost all my plants of nearly all these varieties survived in my garden from an early September sowing and were flowering earlier and for much longer than the varieties I sowed in February.

It's worth putting in the effort now and it gives you one less thing to do in manic spring.

How To Sow

Clear a patch so that it is weed-free, break down any clods with a rake and sow seed into clearly marked lines. The soil should be damp enough to not need any water. In about three weeks, return to thin what comes up, leaving plants with 6in between them. Then, if you have any losses during winter, you'll have plenty of spare plants to end up with the final 12-18in spacing needed.

If you miss the boat on sowing the seeds, you can simply plant out our ready-grown hardy annual seedlings.

Remember Wild Flowers

This year, as well as these hardy annuals, I'm adding a new group of plants to my September sowing list. Ever since I was a child, I've loved wild flowers – I botanised a lot with my father – and this autumn, I'm creating a wild flower garden at Perch Hill. This is not just about my own sentimental journey, these wild flowers will provide a fantastic food source for what, I hope, will become a haze of insects.

My whole concept of what I want from my garden has changed since I started researching a book and working on a television programme about the decline of natural habitats and the wildlife that depends on them. We have already heard about the fall in honeybee numbers, but the same drastic decline applies to solitary bees (1 in 3 native bees have become rare in the last 60 years), and many of our butterflies.

Lovely, showy, flowery flowers are not quite enough for me any more. I want a high proportion of them to be alive with the movement of buzzing, foraging insects, so it's to the single, not fully double, pollen and nectar-rich flowers that I increasingly turn. (In double flowers, it's often the nectaries that have been bred into extra petals – hence the loss of nectar in these plants.)

Bee friendly 

I could never wave goodbye to my stalwart favourites such as the double black Dahlia 'Rip City', but more and more, it's the showy yet simple flowers that I love. I want to walk through Perch Hill in a year or two, scattering butterflies and the day-flying burnet moth as I walk, or stand over a clump of dyer's greenweed, red clover, or bird's foot trefoil and be able to count 20 hoverflies in a minute, and – as soon as the sun comes out – see the busy foraging of lots of red-tailed, honey and good old bumble bees wherever I look.

The Perch Hill garden is already pretty good for all these things, but now I aim for more, and September is the perfect month to get going. Plants grown from seed are cheaper than plug plants, so I can make changes to the insect richness of the garden without laying out a fortune.

Choosing your wild flowers

That's why the sowing of musk mallow, dyer's greenweed, agrimony, betony, red clover, bird's foot trefoil, wild carrot, common knapweed, melancholy thistle, wild parsnip, meadow cranesbill, rough hawkbit and the all-important yellow rattle (parasitical on the stronger, coarser grasses, this aids flower establishment by reducing the competition), has been added to my garden must-dos for the next few weeks.

Many of these plants are most successfully sown at this time of year – into a seed tray and then left outside in the cold until next spring. They do best with a proper cold season and some strong temperature fluctuations to encourage them to germinate.

Viper's bugloss, corncockle and the native, single species blue cornflower (Centaurea cyanus), all British native hardy annuals are going in, too. Standing in a flower meadow at the Olympic Village last week, it was this cornflower that was the most visited by bees – it's a must.

I'm adding marjoram, wild carrot, toadflax, sainfoin, small and field scabious, greater knapweed, lady's and hedge bedstraw, kidney vetch and spiny restharrow to my sowing list, but suspect that these well-drained, chalk soil lovers will not do so well once planted out on my heavy clay soil.

So why not make your own flower meadow? Not only does it look beautiful, but once the basics have been taken care of, it's relatively low maintenance and will do a great service to our nation's struggling wildlife and insects.

It's one of the most obvious garden choices I've ever made – planting flowers as they're meant to be. I've now put together my own wild flower seed mix that's full of native British flowers, and will look stunning throughout the year.