Friday 20 April 2018

Gardening expert Diarmuid Gavin: How to add that last splash of colour to your garden ahead of autumn

As September draws near, enjoy a final burst of summer colour with these dazzling plants

Diarmuid Gavin. Photo: Mark Nixon
Diarmuid Gavin. Photo: Mark Nixon
Perovskia lacey blue

Recently on BBC radio, I listened to an episode of Gardeners' Question Time. The panel of regular experts were being mischievously asked what plants they would banish from their garden or gardens in general if they could. Outrageously (to my mind) crocosmia was mentioned. One man's meat is another man's poison! I love this plant - for the bright show it creates whether planned in people's gardens or as an invasive alien.

In the laneways of furthest Kerry it shoots up and flowers its bright orange underneath the purple and scarlets of wild fuchsia. It's a heavenly sight and, just this week, I saw some inspired planting of its red cultivar, Lucifer, along the driveway of a paving centre - the sword-like foliage emerging from billowing clouds of flowering Alchemilla mollis. The lime green hues seemed to form clouds of smoke from the thrust of the Lucifer shoots which were adorned with deep red colour.

One of the joys of this time of the year is the realisation that with September knocking on our door, there is still a last hurrah from our gardens from plants such as the crocosmia. There's a new energy about to arrive, to elongate the summer. If we don't achieve an Indian summer with our weather, we certainly can with garden planting.

So what other plants will add late summer sparkle over the next six weeks?

The daisy family brings much joy at this time of year - golden yellow rudbeckias, purple echinaceas, bright sunflowers and the seemingly endless supply of pale mauve flowers from Frikart's Aster (Aster x frikartii 'Monch').

Helenium 'Moorheim Beauty' planted in drifts through perennial grasses provides rich early autumnal tints, while Coreopsis 'Moonbeam' will lift flagging borders with lemony yellow blooms.

Japanese anemones are starting to blossom and are a great choice for partial shade - the white petals of Honorine Jubert, pale pink of 'September Charm' and deeper pinks of Prinz Heinrich will make a beautiful collection for September.

Bringing a cottage garden charm to any border are penstemons. Their flowers are not unlike foxgloves and they come in many beautiful colours from the rich deep purple of 'Raven' to the delicious raspberry tones of 'Hidcote Pink'. While easy to grow, penstemons can get hit by a hard winter so it's a good idea to take some cuttings each year to overwinter in the glasshouse.

Sedums are beginning to look absolutely glorious. They are particularly attractive to butterflies taking over from the buddleja as their main area of interest at this time of year. They are often bejewelled with ruby-like carpets of flowers with the lush succulent foliage standing upright.

Dahlias have long made a comeback since their banishment to the notions of 1970s gardening and late summer into early autumn is when these tubers are at their best. It's not only the flowers that look good - the deep claret-coloured foliage of varieties such Bishop of Llandaff offer a surge of enthusiasm in the border.

Garden centres will be full of these species as well as ornamental grasses whose plumes have never looked better, so if you want to ensure good late summer colour in your garden, it's time to go shopping!

Late summer shopping list:

1 Crocosmia 'Emily McKenzie' - looking wonderful at the moment, a bright orange jewel for the garden.

2 Penstemon 'Czar' - a profusion of lilac trumpets with white throats, this perennial is really good value in the garden. Very long flowering, enjoying sun or partial shade, it will withstand periods of drought.

3 Rudbeckia 'Toto Gold' - this is pure sunshine to brighten up the gloomiest spot. Paired with masses of purple Viola, they will complement each other well.

4 Dahlia 'Bishop of Llandaff' - Dahlias were rapidly going out of fashion until Christopher Lloyd at Great Dixter starting championing this wonderful plant. It has bright scarlet flowers that contrast beautifully with dark foliage. Dahlia 'Bishop's Children' retains the dark foliage but with different coloured blooms.

5 Osteospermum 'Tresco Purple' - African daisies are always cheerful plants but I particularly like the intense colour here. Superb plant for a tub or container stuffed with colour.

6 Delphinium 'White Bees' - a really elegant plant, delphiniums provide some fantastic blues for the garden. Cottagey and romantic, its height provides that all-important vertical interest in the border or indeed a container.

7 Perovskia 'Lacey Blue' - this plant is unusual because it is a shrub that puts on a display associated with herbaceous perennials. Otherwise known as Russian Lavender, it can be difficult to use because the stems are so erect but the reward is a cloud of really summery blue flowers.

8 Dianthus 'Whatfield Gem' - a carnation with a zingy dash of ruby and white scented flowers borne aloft on subtle grey foliage.

9 Lobelia 'Queen Victoria' - The cardinal flower has bronze leaves and scarlet red flowers. It does like moist ground so edge of a pond or boggy area would suit best.

This week in the garden...

I've just harvested the last of my early potatoes and put in some late sowings of radish, lamb's lettuce and spring onion. It's not too late to put in spinach, chard, and turnips and even a last sowing of a quick variety of peas.

Harvest onions when their tops fall over and leave them to dry out on soil.

Bulb catalogues are out, so it's time to think about what you will be planting for the spring garden next year.

Make sure azaleas and camellias don't dry out as they are forming buds for next spring.

Raspberry canes that have fruited this year can be cut out and new shoots tied in for next year.

Glasshouses need damping down in the hot weather and plants will get scorched if it's very sunny, so remember to shade where appropriate. Keep an eye out for pests such as red spider mite and order biological controls where necessary.

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