Category: Seasonal Garden Jobs Read time: 6 min read

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Clay soilChalk soilShadeBuckinghamshireOxfordshireBerkshire

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Published

5 April 2026 · 6 min read

Last reviewed

19 July 2026

Reviewed by a senior CGM team member.

The short answer

Quick Answer

Key August garden jobs in the Chilterns: water containers and new plantings, deadhead flowering plants, mow the lawn less often in dry spells, prune wisteria and summer-flowering shrubs, harvest vegetables, and plan autumn planting. August is often hot and dry in the Chilterns, so watering and drought management are the priority.

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Why August Is a Tricky Month

August is the month when the garden can start to look tired. The flush of early summer is over, the weather is hot, and many plants are running out of steam. But August is also a month of opportunity: with careful management, the garden can look good right through to October. The trick is to stay on top of watering, deadheading, and to start planning for autumn.

In the Chilterns, August is typically the driest month, with 40 to 50mm of rain on average. Temperatures reach 22 to 25 degrees Celsius regularly, with heatwaves pushing 30 degrees or more. The chalky soils around High Wycombe, Marlow and Henley-on-Thames drain fast and need more watering than the clay soils in Aylesbury and Bicester, which retain moisture better.

Watering in August

August is the peak watering month. Containers, hanging baskets, new plantings and vegetables all need regular water.

  • Water in the early morning or evening to reduce evaporation.
  • Water deeply once a week rather than lightly every day.
  • Prioritise containers, new plantings, and vegetables. Established shrubs and trees usually do not need watering.
  • Use grey water (bath and washing-up water) for established ornamental plants. Do not use on edibles.
  • Install a water butt if you have not already. Even a small one helps.
  • Use a drip irrigation system for containers and beds. It is more efficient than a hosepipe.
  • Mulch bare soil to retain moisture.

See our Chilterns heatwave guide for drought management.

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Lawn Care in August

  • Mow less often in dry spells. The grass is not growing much, and cutting stresses it.
  • Set the mower blades high (40 to 50mm) to shade the soil and retain moisture.
  • Leave clippings on the lawn in dry spells to act as mulch.
  • Water the lawn only if you can do it regularly. Sporadic watering does more harm than good.
  • If the lawn goes brown, accept it. Grass goes dormant and recovers when the rain returns.
  • Do not feed the lawn in August. Soft growth is vulnerable to drought.

Deadheading in August

Keep deadheading to extend the flowering season. Many plants will keep flowering into September if you stay on top of it.

  • Roses: deadhead weekly. Cut back to a strong outward-facing bud.
  • Dahlias: deadhead regularly. The flowers keep coming until the first frost.
  • Cosmos and annuals: deadhead to keep them flowering.
  • Sweet peas: keep picking. Do not let them set seed or they stop flowering.
  • Perennials: deadhead salvia, hardy geraniums, echinacea. Some will repeat flower.

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Pruning in August

  • Wisteria: shorten the long whippy shoots to 5 to 6 leaves from the main framework.
  • Summer-flowering shrubs (philadelphus, weigela, deutzia): prune immediately after flowering.
  • Trained fruit trees (espaliers, fans): summer prune to control growth.
  • Evergreen hedges: final trim of the year in late August.
  • Lavender: trim after flowering to keep compact. Do not cut into old wood.

See our hedge cutting guide and pruning guide for detail.

Harvesting in August

August is the peak harvest month for vegetables and fruit.

  • Tomatoes, courgettes, cucumbers, beans: pick daily to keep plants productive.
  • Soft fruit: autumn raspberries, blackberries, plums, apples (early varieties).
  • Onions and shallots: harvest when the tops fall over and yellow.
  • Garlic: harvest when the lower leaves are yellow.
  • Maincrop potatoes: harvest as needed. Leave the rest in the ground until October.
  • Herbs: cut and dry or freeze for winter use.

Sowing in August

August is the time to sow for autumn and winter crops.

  • Sow salad crops (lettuce, rocket, mizuna) for autumn picking.
  • Sow spring cabbage for planting out in September.
  • Sow oriental greens (pak choi, mibuna, mizuna) for autumn harvest.
  • Sow spinach for autumn and winter cropping.
  • Sow green manures (phacelia, mustard) on empty beds to dig in before winter.

Pest and Disease Control in August

  • Watch for blight on tomatoes and potatoes. Remove affected leaves immediately.
  • Watch for wasps on ripening fruit. Trap them or pick fruit early.
  • Watch for vine weevil adult damage on rhododendrons and camellias (notched leaf edges).
  • Watch for powdery mildew on susceptible plants (asters, monarda, roses). Improve air circulation.
  • Watch for ants farming aphids on plants. Control the ants to control the aphids.

Planning for Autumn in August

August is the month to plan autumn planting. Order bulbs, trees and shrubs now for delivery in September and October.

  • Order spring-flowering bulbs (daffodils, tulips, alliums) for September planting.
  • Order bare-root trees and hedges for November delivery.
  • Plan new borders for autumn planting. Autumn is the best planting time.
  • Plan lawn renovation for September. See our lawn renovation guide.
  • Buy our Chiltern Guides for autumn lawn care and bulb planting.

Common August Mistakes

  • Not watering enough. Containers and new plantings need daily watering in hot weather.
  • Watering at midday. Most water evaporates. Water in the morning or evening.
  • Not deadheading. Plants stop flowering if allowed to set seed.
  • Cutting the lawn too short. Short grass is vulnerable to drought.
  • Not harvesting vegetables. Plants stop producing if fruit is left on.

Frequently Asked Questions

Should I water my lawn in a drought?

Only if you can commit to watering regularly. Sporadic watering does more harm than good. Letting the lawn go dormant is fine. It will recover when the rain returns.

Can I still plant in August?

Yes, but you must water daily for the first two weeks. Autumn planting (September to November) is better.

When should I order spring bulbs?

Order in August for September delivery. Popular varieties sell out by October.

Get Help with August Garden Jobs

If you need help with August garden jobs in Oxfordshire, Buckinghamshire, Berkshire or Bedfordshire, send us a WhatsApp with photos and we will aim to respond within 12 to 36 hours, Monday to Sunday.

WhatsAppGet a Quote

Further Reading

Estate Note

In mature gardens, timing is critical. Established plants respond differently to seasonal work than young plants. Watch the weather forecast and adjust plans accordingly.

Useful next steps

Put this advice into practice

Use the relevant CGM tool or follow a related guide, then send us a few photos if you would like a tailored plan.

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Sources and citations

This article draws on the following sources. Specific claims are cited inline where relevant.

  1. CGM field records (2026-07. Site observations from gardens across Oxfordshire, Buckinghamshire, Berkshire and Bedfordshire.
  2. Royal Horticultural Society (2024). RHS Gardening Advice and Plant Finder. Available at rhs.org.uk.
  3. Met Office (2024). Regional climate averages, South East England. Available at metoffice.gov.uk.
  4. British Geological Survey (2024). Soil parent material data for the Chilterns and Thames Valley. Available at bgs.ac.uk.