Many tender perennials are at their best in late summer, when they provide a jolly splash of colour. They are more drought tolerant than annual bedding plants, making them perfect for your summer garden.

Popular tender perennials include:

  • Verbena, with varieties such as deep pink ‘Sissinghurst’ and rich purple ‘Homestead Purple’
  • Osteospermums
  • Diascia ‘Ruby Field’ and D. vigilis for a low, pink carpet 
  • Bush fuchsias or marguerite daisies for height and substance
  • Canna or abutilons for a tropical effect.

 

For tender perennials with particular drought-resistant foliage, helichrysums include:

  • Silvery H. petiolare 
  • Lime-green ‘Limelight’
  • Cream-variegated ‘Variegatum’

The ferny foliage of golden yellow bidens provides vigorous ground cover. And for edging a sunny border, try the mossy foliage of rock daisy (Brachyscome multifida) or the variegated forms of felicia—both flower well.

 

Those annuals

Hardy annuals, such as sweet william (Dianthus barbutus) and mignonette (Reseda odorata), don’t flower for as long as tender perennials or half-hardy annuals, but they are good for filling gaps in late summer.

For continuous blooms until the first frosts, sow some extra seeds every few weeks until early June. If it's too late,hardy perennials can be used instead of bedding plants in borders or containers.

Choose ones with a long flowering season, such as Dianthus ‘Doris’.

 

Longer flowering

A garden can start to flag in August when some summer-flowering perennials run out of steam, especially in a dry year. However, many tender perennials and larger-flowered hardy annuals, such as pot marigold (Calendula officinalis) and cornflower (Centaurea cyanus), will bloom for longer if adequately watered, boosted with a general liquid feed and regularly deadheaded (as a time saver, use shears for those with lots of small blooms).

For additional colour, group together tender perennials that put on a good late-season show, such as the shrubby salvias S. uliginosa (clear blue) and S. fulgens (red). Or late-flowering bedding plants, such as Chinese aster (callistephus), celosia, coleus (solenostemon), salpiglossis, zinnia, and annual penstemon and rudbeckia.

Garden centres also stock compact dahlias and chrysanthemums in bud and flower.

 

Perennials for cool and shady gardens

Cool and shady plants for late summer

An elegant scheme using white and soft blue to emphasise cool shade. All plants thrive in humus-rich, moisture-retentive soil. Flowering season from July to September.

1. Hydrangea macrophylla ‘Mme Emile Mouillière’

2. Aconitum x cammarum ‘Bicolor’

3. Phlox paniculata

4. Impatiens F1 hybrid (busy lizzie) flowers start in June.

5. Geranium wallichianum ‘Buxton’s Variety’ first flowers open in June.

 

 Perennials for gardens in hot spots

Perennials for garden hot spots

The rich colours of the penstemon and the buddleja give punch to the pastel blues and pinks used in this scheme for free-draining soil.

The flowering season is from July to September.

1. Buddleja davidii ‘Royal Red’

2. Echinops bannaticus

3. Penstemon ‘Garnet’

4. Calamintha nepeta

5. Osteospermum ‘Stardust’ flowers from May

 

 Foliage and sun

Foliage and the sun

This August display offers a contrast of leaf size and texture.

All plants enjoy moist soil in full sun.

1. Cimicifuga var. simplex Atropurpurea Group white flowers from August to October.

2. Miscanthus sinensis ‘Zebrinus’ flowers until November.

3. Hosta ‘Royal Standard’ white flowers in August.

4. Rudbeckia fulgida var. sullivantii ‘Goldsturm’ yellow flowers in August and September.

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