August gardening guide: what to do in your garden this August

August gardening guide: what to do in your garden this August

August marks the last month of summer, and gardens and vegetable plots are still at their peak. Weather permitting, it’s the perfect time to enjoy your garden as an entertaining space while preparing for the seasonal shift ahead.

Many summer perennials will finish flowering by the end of the month, while late-summer shrubs like Buddleja and Abelia – along with richly coloured autumn daisies such as Echinacea, Rudbeckia, and Helenium – will take centre stage. Quick-growing salad crops such as lettuce, rocket, and radish can still be sown, and deadheading flowers will help extend the floral display well into September.

Planting

Add autumn colour
Plant autumn-flowering cyclamen to replace any faded summer bedding. Mark gaps in borders now so you know where to plant spring-flowering bulbs over the coming months.

Sow perennials and take cuttings
Sow seeds of perennials that require frost to germinate, leaving them outside in a cold frame. Take pelargonium cuttings to raise free plants for next year.

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Make new strawberry plants
Use runners from this year’s strawberry plants to create new ones. Peg a runner into a pot of compost placed beside the parent plant, water well, and let it root before cutting it free in a few weeks. Remove excess runners to conserve energy. Remember, strawberry plants should be replaced every four years as yields decline.

Final salad sowings
Sow the last rows of lettuce and rocket, which prefer cooler conditions and are less likely to bolt. Later in the season, protect these crops with cloches as the weather cools.

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Care and maintenance

Lavender pruning
In late August, after flowering, trim spent flowers from lavender and lightly clip to shape for next year. Avoid trimming French lavender (Lavandula stoechas), which flowers continuously – simply deadhead instead.

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Refresh tired perennials
Cut back plants such as hardy geraniums, catmint (Nepeta), and lady’s mantle (Alchemilla mollis) to encourage fresh foliage. Some may produce a second flush of flowers if the weather is kind.

Tomato care
Thin out tomato foliage to improve air circulation and light penetration, encouraging fruiting. Pinch out the top growing point once several trusses of flowers have set to divert energy into ripening fruit. Keep removing any new top growth that appears.

Holiday watering
If you’re away, make arrangements for container plants to be watered regularly.

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Harvesting

Pick regularly
Beans, courgettes, and salads should be harvested every day or two to maintain peak quality and encourage further cropping.

Second crop of broad beans
For a late harvest, cut down finished broad bean plants to 15cm near the growing point in late July or early August, feed well, and they may produce a smaller second crop by early autumn.

Onions, garlic, and shallots
Harvest when the foliage turns brown. Bend over the tops to aid ripening, then lift them in a dry spell and leave them on the soil to dry. If the weather is wet, dry them under cover in a greenhouse, conservatory, or other warm, well-ventilated space. Ensure bulbs are completely dry before storing to prevent rot.

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Wildlife and pests

Keep bird baths topped up with fresh water. Leave some seed heads and windfall fruit to provide food for birds and small mammals.

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Other garden tasks

• Spot-treat weeds in the lawn and fill holes with gritty compost as part of lawn care routine.
• Keep ponds and water features topped up; clean water butts if empty.
• Sweep patios regularly and treat small weeds as they appear.
• Hoe weeds from gravel areas and apply residual weed killer to prevent regrowth.
• In warm weather, dampen the greenhouse floor in the morning to reduce temperature and increase humidity.