Oak Leaf Gardening Monthly Cuttings
Newsletter 51 - August 2015
What to do now

Ornamental plants

  • Carry on deadheading, particularly repeat-flowering roses, and cut back flower spikes on perennials which have finished flowering.
  • Trim laurel, beech, hornbeam, leylandii, thuja, lavender, rosemary and santolina hedges.
  • Prune summer flowering shrubs such as lilacs and mock oranges as soon as they have finished flowering.
  • Get plants for free by taking cuttings from pinks, verbena, penstemons and osteospermums.
  • At the end of the month take softwood cuttings from pelargoniums, fuchsias and other tender plants you want to keep over winter.
  • Clear older and rotting waterlily leaves from ponds and top up the water level if required.
  • Plant autumn flowering bulbs.
  • Start to force bulbs, such as hyacinths, for Christmas flowers.
Fruit and veg
  • Sow early carrots, peas, turnips, parsley, lettuce, baby spinach leaves, kohl rabi, winter spinach, coriander, spring cabbages, pak choi and Chinese cabbage.
  • Harvest blackberries, loganberries, peaches, nectarines, apricots, summer raspberries, early apples, French beans, runner beans, lettuce, beetroot, turnips, courgettes, onions, leeks, marrows, calabrese broccoli, summer squashes, sweetcorn, second early potatoes, tomatoes, globe artichokes and greenhouse grown tomatoes, peppers, aubergines, cucumbers and melons.
  • Pinch out outdoor tomatoes (nipping off the top of the plant). Keep on feeding indoor tomatoes, pinching out shoots and removing yellowing leaves.
  • Prune gooseberries, redcurrants, blackcurrants, summer fruiting raspberry canes, peaches, apples and fan-trained fruit trees.
  • Cut strawberry runners from the parent plants – layer them into pots first if you want more plants.
General tasks
  • Keep on weeding, watering and feeding, particularly newly planted specimens and container grown plants.
  • Ventilate your greenhouse well in hot weather, add extra shading if needed and damp it down regularly.
  • Keep an eye on sticky fly traps in greenhouses so you can monitor pest levels.
  • Raise your lawn mower's cutting height, or mow less frequently, in dry weather.
  • Start saving seeds from plants which have finished flowering.
  • Take photos of what your garden looks like this month so you can remember what's growing where to help you plan design changes.
Plant of the monthVeronicastrum virginicum 'Fascination'

Veronicastrum virginicum 'Fascination' is a tall herbaceous perennial, growing to 1.8m height, and displaying long spires of lavender coloured flowers in July and August. It looks great at the back of a border and suits prairie style planting schemes as well as cottage gardens. Cut down the spent flower spikes to prolong flowering and cut the whole plant down to ground level in the autumn. Find out more...

Problem of the monthAnts

Ants generally cause more problems for people than plants, but there are a few situations where they can cause damage to your garden. Collecting seeds from seed trays can be a nuisance and their nest building activities can cause root damage in light soils and bare patches on lawns. However, while they do eat leaves, they rarely consume enough to cause permanent damage. Find out more...

In the news

Record year for Green Flag Awards

The Green Flag Awards scheme, which recognises excellence in green spaces, has granted the award to a record 1,582 parks, cemeteries, universities, shopping centres and community gardens this year. This is up from the 1,470 awards given out in 2014. New recipients include the University of Bradford's main campus, the Tuckton Tea Gardens and Purwell Meadows.

New Carol Klein series explores plant origins

A new BBC2 series, Carol Klein's Plant Odysseys, started this week. The series of 4 programmes features a new plant each week, exploring its history and seeing Carol travelling around the world to discover its origins. Last Monday's show (available on the BBC iPlayer) featured roses, next week discovers tulips and the following weeks will feature irises and water lilies.

Natural England study of green bridges

A report by Natural England has shown that 'green' bridges, planted with local trees, shrubs and other vegetation, can both prevent wildlife species becoming isolated by the presence of roads and can also reduce accidents. Natural England hope that the study will encourage developers to make green bridges a key aspect of future transport projects, either by creating new bridges for wildlife or 'greening' existing bridges.


Dare you dahlia?

Dahlias are stalwarts of gardens of all sizes and styles. Whether you’re planting the classic Dahlia ‘Bishop of Llandaff’ or getting more adventurous with Dahlia ‘Ryecroft Marge’, dahlias will give you great value with flowers from summer through to autumn, and they’re at their best this time of year.

Dahlias are classified by type (eg single-flowered, pompon, waterlily) and size (eg giant, medium), with the largest blooms being over 30cm wide. The great variety of dahlias available makes them perfect for many situations, from beds and borders to pots and windowboxes, and suitable for anything from a lush, tropical display to a traditional cottage garden. They were introduced into Europe by the 18th century Swedish botanist Anders Dahl, who brought them over from Mexico, and after whom the plants are named.

Dahlia 'Bishop of Llandaff'
Dahlia 'Bishop of Llandaff', known as "The Bishop".

Dahlias should be planted out in the spring once the worst of the frosts have passed, or started off earlier in pots indoors. Mulch them with rich organic matter and when they start to put on growth feed them every 4 weeks with fish, blood and bone (or a general purpose fertiliser) until September, at which point switch to a high potash feed.

The young stems can be pinched out (or ‘stopped’) to get a bushier plant. Remove the buds from the leaf axils at the top of each stem – this will encourage the plant to put all its energy into lower growth and, most importantly, into flower formation. Stake the plant to stop it flopping over, with taller varieties you will need quite a substantial support to keep the flowering stems upright.

Once flowering has started deadhead regularly and remove entire stems which have flowered to promote new growth from the base.

If you are growing dahlias for cut flowers, cut the stems then trim them to the required length under hot water (this will prevent air getting into the stem) and at a 45° angle. Keep your arrangement in a cool, dry place and it should last from 7 to 10 days.

Unless your dahlias are grown in a particularly dry and protected spot, the tubers should be lifted in the autumn to prevent them rotting away. Lift them when the foliage has been slightly blackened by frost. You can take this opportunity to divide the tubers, just make sure that each section has a bit of main stem left on it (or this can be done in the spring before re-planting). Remove any clumps of wet soil, trim the stems to about 15cm and then turn them upside down to allow the sap to drain out. Put them in a dry, frost free place for a few days. When they are completely dry, cut the stem down and remove any damaged or diseased parts. Dust with sulphur and keep warm and dry over the winter, wrapped in newspaper or in shallow trays of dry sand. Check them regularly to ensure none of them are rotting.


What's on this month

Enjoy the sunshine at this month's gardening events:

  • 30th July to 2nd August - RHS Hyde Hall Flower Show, RHS Garden Hyde Hall, Chelmsford, Essex.
  • 31st July to 6th August - Dig The City Garden Festival, various locations around Manchester.
  • 9th August - Bee Fayre, Enys House & Gardens, Penryn, Cornwall.
  • 14th August - Herbs In The Garden, The Bishop's Palace, Wells, Somerset.
  • 14th & 15th August - Shrewsbury Flower Show, The Quarry Park, Shrewsbury, Shropshire.
  • 16th August - Bonsai Demonstration, The Birmingham Botanical Gardens, Edgbaston, Birmingham.
  • 20th to 23rd August - Southport Flower Show, Victoria Park, Southport, Lancashire.
  • 22nd & 23rd August - British Gladiolus And Gough Park Allotment Show, Capel Manor Gardens, Enfield, Middlesex.