Monthly Advice - August jobs in the Garden



  • Most hedge plants will need their last trim before the colder seasons set in. Conifer hedges may be the exception to this because they continue to grow until October and can have a final going-over then. To get a level top to your hedge bash in two posts at either end of the hedge and tie some twine between the two at the height that you are trying to achieve. Tackle the sides of the hedge first and start at the bottom so that you can see more clearly how much you have taken off as the cuttings fall to the ground and do not get caught on foliage below. The aim is to "batter" the hedge which means to leave the hedge wider at the base than at the top so that it can withstand winter weather better. Once you are happy with the sides of the hedge, trim the top last using the twine as your guide. Conifer hedges need to be maintained within the limits of the height and width you prefer for them because they, yew being the notable exception, will not grow from old wood. And if your hedge is composed of a large leaved plant like laurel, for aesthetic's sake you are best to prune it with secateurs so that you trim off whole leaves rather than use an electric shearer which will cut through half a leaf leaving the remainder to brown on the hedge.
  • To prevent box blight - which is becoming more of a menace it is worth considering leaving your box balls and hedges a little looser and even removing some of the internal branches so that more air can circulate through and around the plant to prevent the fungus spores of the blight from settling. Another preventative measure is to try to ensure that your box has no other plants growing closer than 50 cm for the same reason. You are also less likely to get blight if you prune your box in winter when the disease is dormant.

Fruit Trees

  • If you are growing early apple varieties like Katy or Discovery you may well be able to start harvesting topfruit at the end of the month. Cup the fruit in your hand and twist gently. The fruit should come away, stalk intact, very easily if it is ripe. Early fruiters tend not to be keepers so eat your harvest up promptly. Any damaged fruits can go to the chickens or straight on the compost heap.
  • Fan trained plums, damsons and sweet cherries should be pruned after they have fruited. Cut back by half all the shoots that have fruited.
  • Nectarines, peaches and acid cherries like Morello, need all of the shoots that grow from the main branches pruned to four inches and any sideshoots that grow from the latter should be pruned back to 2 inches.
  • Cordon fruit are treated slightly differently: any side stem from the main stem should be cut back to three inches. Any shoots that were cut back like this last year will have grown their own side shoots and in turn these need to be cut back to an inch to encourage fruit spurs. Once the main stem has reached the limit of its support it should be pruned as per the main side stems, ie back to 3 inches.
  • Importantly, all fruit trees that are growing close to a wall will inevitably suffer dehydration so water their roots well.

Garden trees and shrubs

  • The basics apply here: water wisely and thoroughly especially if your shrubs or trees are newly planted.
  • Weed around the base of plants on a dry day, preferably using a dutch hoe which will cut the tops of the weed off and leave them to wither and compost back down into the soil.
  • Any shrubs kept in pots should be well watered and fed at least weekly. Woody shrubs require a high potash fertiliser to encourage any wood to ripen rather than remain soft and sappy and delicious for pests or easy to damage in winter.


  • As with July, your roses will require dead heading down to a good, outward facing bud at least one or two leaves below the flowered stem. The emphasis should be on finding a strong bud to increase your chances of another flower forming, but remember that the harder you prune the more vigorously the rose will respond with a strong shoot. Feed and water if the dead-heading evolves into a pruning session and you cut back many flowered stems.
  • Rambling roses will need pruning after they have finished flowering. The rule is that ramblers flower on last year's wood so there are two stages to dealing with ramblers. First you need to cut out much older wood to the ground to encourage new growth and cut sideshoots that have flowered back to 2-3 buds from the main stem. Second, any new wood should be tied in ready to flower the following year.
  • Wild roses should be left as they are in the hopes that their spent flowers will produce beautiful hips in the autumn.


  • The whippy growth that your wisteria will have produced should be cut back so that they are within five or six buds from the main stem or use that same whippy growth to tie in to extend the framework of the wisteria if it is a young specimen. Where a wisteria does not flower may be down to an incorrect pruning regimen but often it is because the wisteria is not a named variety that has been grafted on to vigorous rootstock. To check that your wisteria has been grafted look for a slightly swollen area at the base of the main stem (if they come from us, no need as they are all grafted . Without this assurance your wisteria may take many years to flower, or never do so, so it is worth investing in a named variety from a reputable supplier...
  • You may need to get a ladder out to dead head the top section of your climbing roses, honeysuckles and jasmines once they have finished flowering.

Soft Fruit

  • Summer fruiting raspberry canes that have produced fruit need to be pruned out at ground level and then any strong, new canes should be tied in to your support structure. Do not bother to tie in any weak canes; they will not fruit well. If any of the new canes have grown taller than the support structure leave the top in place until winter when you can prune it back when the plant is dormant.
  • Cordon and fan trained redcurrant and gooseberry bushes can be pruned back now the fruit has been harvested.
  • Unless it is very dry, August is a good time to plant new strawberry plants so that they can build up some ballast before winter. Keep watering them once you have planted. If there is a serious shortage of water or you are going to be away, put this job off until September. Where you have old strawberry plants that are virus free (the virus can be detected by streaky, rather than plain green foliage) you can use some of their runner or plantlets as new plants. Always plant strawberry plants on ground where there have not been strawberries grown recently.
  • Anyone who really loves their strawberries might want to try potting up some plantlets in pots so that they can be forced for early fruit next summer. Use an 18 cm pot and leave them outside for the rest of the summer. In autumn, put the pots on their side so that they do not become too wet and early in the new year take the pots inside into a greenhouse so that they start to produce fruit early on in spring.


  • When the flowers are beginning to dry out on the plant and you have harvested enough to flavour sugar, or scatter in your bath of an evening, trim all the flowered spikes back and take about 2.5 cm of the leafy growth at the tips of shoots at the same time to prevent your lavender bushes from becoming leggy and mis-shapen. If your lavender has become twiggy and straggly because lavender rarely grows from old wood, your best bet may well be to take cuttings of your old plants or to buy in some new plants to replace the old ones. Lavender does thrives in a free draining soil so if you are gardening on a heavy, clay soil make sure that you add plenty of grit to the soil to improve drainage.


  • Unbelievably it is time to start thinking about daffodils for next year. Ideally daffodils and narcissi should be planted by the end of October at the latest in random drifts in grass so that they can naturalise and spread over the years. For anyone gardening on a smaller scale there are many miniature varieties that look good in raised beds or pots or rockeries. A good tip, but a hard one to carry out, is to mark any bulbs that you put into borders to prevent you digging them up when their foliage has died down as you weed and plant over the rest of the year. Plant the bulbs two to three times their own depth and add a little bonemeal to the planting hole. If you are gardening on heavy clay soil sprinkle some grit at the bottom of the planting hole as well.
  • Colchicums can also be planted during August. They look best surrounded by grass or other plants since their flowers arrive before their leaves and they can appear quite naked otherwise.
  • Having got over the shock of planning for next spring it is worth turning to Christmas because now is the time to order prepared hyacinth and some narcissi bulbs and pot them up so that they will be ready for December. Ordinary potting compost is a perfectly acceptable planting medium unless you are planting the bulbs in a decorative pot that has no drainage holes in which case use bulb fibre. Place several bulbs in your pot on a layer of compost so that they are almost touching. Then cover the bulbs so that only the very tip of the bulb is poking above the soil. Put the pots into a cool, dark place and after about 6 weeks inspect them daily for growth. Once you can see about an inch of shoot then bring the pots in to reasonably cool but light conditions.

Olive and Bay

  • Feed once a month and water regularly so that the soil never dries out.


  • Cut back perennials, especially ones like Achilleas which have a tendency to collapse and smother plants around them. Late flowering perennials like asters and rudbeckias are worth staking. Geraniums that are now over should be cut down, watered and fed in the hopes that they may return with a vengeance for an autumn show.
  • Book a friend or somebody to keep watering your garden and harvesting any veg while you are away.
  • Take pelargonium cuttings. Use a gritty, light soil cut 50:50 with vermiculite as your potting medium. The leaves of scented pelargoniums are great flavourers for puddings - and will scent your bath too.
  • Blossom end rot can occur in tomatoes that have been watered haphazardly. You will see a black spot on the end of any tomato which has succumbed and this will spread and rot the tomato. Keep watering your plants thoroughly to try to prevent the condition worsening.
  • During a hot spell, splash water on the floor of your greenhouse to keep the atmosphere humid and to cool proceedings. Leave the doors and ventilators open during the day.
  • Your vegetable garden should be in full swing. It may be hard to motivate yourself to keep sowing seeds when you are facing a glut of courgettes, amongst others, but you will thank yourself if you can summon up the energy to sow some rows of chard, kale and winter lettuces like Salad Bowl or Merveille de Quatre Saisons to keep you going into the winter. Leave out some blocks of wood or up turned pots for slugs to shelter in overnight and then turn them over in the morning to give the birds a slug feast or, for the less squeamish, dispose of them at will. A wellington boot heel usually does it!
  • Raise the blades on your lawn mower if the weather is hot and dry; you may find that you don't have to mow quite so frequently too. However for established lawns it is unnecessary to water them because the grass will recover once the rain does come again. Towards the end of the month use a high phosphate fertiliser to benefit the roots of the grass to survive the rigours of the winter ahead.
  • If you are planning a new area of lawn it is worth starting to prepare the ground now. The wet and warm of autumn is the most user-friendly time to try to establish a new lawn because it will need lots of water and you have the advantage of autumn dew and warm soil providing optimal conditions for grass seed to germinate or turf to establish. Dig through the area to turf and remove any weeds now and then in the fallow period before sowing any perennial weeds will have the opportunity to grow again. At which point you can nobble them with a spray of glyphosate before laying the turf or seeding.
  • Lots of medicinal herbs are at their best in August, valerian, feverfew, camomile and St John's wort can all be harvested now.
  • Fill up your bird baths with water not only because they will appreciate it but birds eat pests and slugs and keeping water available attracts them and keeps them in your garden.
Tags: advice  august 
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