August gardening tips: keeping the garden going

Val Bourne

August is dire for gardens, with many plants are already gone. But there is hope...

August gardens can look weary, if not exhausted – but you can also stop the tired look by pre-emptive mulching with well-rotted organic material in early May - but always on damp soil. This will keep any moisture trapped underneath. You can make a simple mulch using partially decomposed grass clippings.

However, whenever you mulch you nearly always get more slugs. So don’t add this mulch near hostas, dahlias, delphiniums or other favourite slug fests.

Thirsty plants

  • Phloxes
  • Asters
  • Persicarias
  • Aconitums
  • Heleniums
  • Monardas

A quick and easy mulch for thirsty plants

Put the grass clippings on a plastic sheet and leave for one day in sunshine. Turn the pile of clippings and leave for another 24 hours, or until they have turned brown. Apply the mulch by spreading round each plant. Never cover the crown of a plant.

The Chelsea chop

Another way to keep the garden going is to give plants a Chelsea chop in May - roughly when the flower show takes place. They will bush out more, be shorter in stature and flower later. This is very good for campanulas, sedums, phloxes and asters. But I wouldn’t recommend the Chelsea chop if you’re on thin, dry soil or in drier parts of the country - unless you’re prepared to water.

Cultivate some drought-tolerant plants

Several types of plant are specially adapted to strong sunshine and dry conditions and they positively thrive in hot, dry summers.

Aromatic plants

Any pungent plant has an oily coating designed to screen out the sun’s drying rays and many peak in August.

1. Lavandula x intermedia ‘Grosso’, ‘Dutch Group’  and ‘Grappenhall’ (now renamed ‘Pale Pretender’)
These billowing lavenders (or lavendins) have long, tapering flowers held on very long stems above a rounded mound of thick, felty foliage. They peak in late-summer and can be trimmed back to form a tight orb in September. Never cut them back hard and replace every 5th year - so take cuttings (40 - 60 cm).

2. Thymes and oreganos
Forms or hybrids of Origanum laevigatum include ‘Herrenhausen’ and ‘Hopleys’ and the hybrid ‘Rosenkuppel’. The long wiry stems are topped by two-toned purple or pink flowers and they leave an excellent winter seed head. (30-40 cm) Good low-growing thymes include Thymus pulegiodes ‘Tabor’  and ‘Silver Queen’.

3. Achillea ‘Walther Funcke’
The best marmalade-orange achillea with intricate, acrid, silvery foliage and large flat heads (50 cm).

4. Anthemis ‘Susanna Mitchell’

This sprawling lemon-yellow daisy with cut silver foliage flowers in early summer.  But if cut back hard after the first flowering it becomes an August star (30 cm).

5. Nepeta  ‘Six Hill’s Giant
Cut back hard in mid-July for a sheet of sky-blue flowers in August (a floppy 60 cm).

Fleshy-leafed plants

Some plants with thick water-filled leaves can withstand dry conditions and purple-leafed sedums, house leeks, phormiums, eucomis and succulents will never flag. However their soft stems may well attract vine weevil. Check by tugging the main stem away from the roots. If healthy it will stay attached.

1. Sedum ‘Purple Emperor’
This wonderfully poised, upright sedum combines dark, neatly crimped leaves with ruby-red flowers. These are extremely attractive to hoverflies and bees. Simply the best sedum.

2. Phormium ‘Sundowner’
This multi-striped pink, green and cream phormium - provides linear structure.

3. Sedum telephium  ‘Karfunkelstein’ (syn ‘Xenox’)
Larger pewter-toned, dusky grey-purple leaves and branching stems of pink flowers (30 cm).

4. Sedum ‘Mr Goodbud’
A new green-leaved sedum that won’t flower until September. But the wide heads of green buds will look just as good as flowers in August (40 cm).

5. Eucomis comosa ‘Sparkling Burgundy’
It has proved hardy even coming through last year’s winter. Wavy swords of deep-red crinkled leaves make a shuttlecock. ‘Pineapple’ flowers amy follow (40 - 60 cm).

Tender plants from warmer climes

Some plants from South America or the Mediterranean start into growth later here due to the weather, so they don’t peak until late summer and autumn. They offer great value in August and they include penstemons, dahlias, salvias, verbenas and diascias. Lots of other bedding plants also perform in August and these include petunias, pelargoniums, osteospermums, eliotropes, agapanthus and verbenas.

Take a masterclass

If you feel that your garden is drab in August make a pilgrimage to the Cotswold Wildlife Park and Garden near Burford in Oxfordshire. The Walled Garden is a sensation and the borders will inspire you. (It is listed in the Good Gardens Guide -

Truly perennial August performers

There are 'backbone' plants that shine in August and they include crocosmias, kniphofias, phloxes, European asters, heleniums and buddlejas.

1. Helenium 'Sahin’s Early Flowerer'
Shimmering mahogany and orange daisies - every one different - on this strong hybrid helenium (100 cm). Read more about this heleniums here.

2. Aster x frikartii 'Monch'
Large lavender-blue daisies with very long rays. This European aster tolerates much more drought and flowers for weeks. Tends to flop a little, so better at the front (50 cm). More on asters.

3. Crocosmia 'Emberglow'
A blaze of dark-red flowers in August (90 cm). More on crocosmias.

4. Rudbeckia 'Goldsturm'
Crisp yellow daisies with brown centres set against good green foliage (90 - 120 cm). Find out more about rudbeckias.

5. Kniphofia 'Timothy'
Subdued gentle pokers that smoulder like red-hot iron on a blacksmith’s forge (80 cm). Find out more about kniphofias.

The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.