Beyond Mulch: How We Use Gravel and Permeable Surfaces to Conserve Water

Why Water Conservation Matters in the Chilterns

The Chilterns is one of the driest parts of the UK. Annual rainfall in the Thames Valley around Reading, Maidenhead and Slough averages just 600 to 650mm, less than Jerusalem. The chalky soils drain fast, so even after heavy rain the soil can be dry within days. Climate change is making summers hotter and drier, with hosepipe bans now common in South East England.

Water conservation in gardens is not just about saving water. It is about creating gardens that thrive without constant watering, that survive heatwaves, and that are sustainable in the long term. This guide explains the techniques we use to create water-efficient gardens across Oxfordshire, Buckinghamshire, Berkshire and Bedfordshire.

Mulch: The First Line of Defence

Mulch is the single most effective water conservation technique. A 5cm layer of bark or compost reduces evaporation by 70 percent, keeps soil temperatures 5 to 10 degrees cooler, and suppresses weeds. Apply mulch in spring when the soil is moist, and top up annually.

Types of mulch:

• Bark: cheap, long-lasting, looks good. Best for ornamental borders.
• Compost: feeds the soil as well as mulching. Best for vegetables and roses.
• Well-rotted manure: rich in nutrients. Best for hungry plants like roses and vegetables.
• Gravel: looks good with Mediterranean plants. Permanent, but does not feed the soil.
• Leaf mould: free if you make it. Best for woodland plants.

See our mulching guide for detail.

Gravel Gardens

Gravel gardens are the ultimate water-efficient garden. They need 50 to 70 percent less water than traditional borders, look good all year, and support a wide range of drought-tolerant plants. The classic gravel garden is the Beth Chatto garden in Essex, but the style works equally well in the Chilterns.

How to Build a Gravel Garden

1. Clear the area of all weeds, especially perennial weeds.
2. Improve the soil with compost if needed. On chalk, no improvement is usually needed.
3. Plant drought-tolerant plants in autumn so they establish before summer.
4. Apply a 5cm layer of gravel over the soil. Use 10 to 20mm angular gravel, not pea shingle.
5. Water regularly for the first season until plants are established.
6. After the first year, do not water. Drought-tolerant plants do not need it.

Best Plants for Gravel Gardens

• Lavender
• Rosemary
• Salvia
• Stipa tenuissima
• Verbena bonariensis
• Eryngium
• Sedum
• Alliums

See our drought-tolerant plant guide for more.

Permeable Paving

Permeable paving allows rain to soak into the ground rather than running off. This reduces flooding, recharges groundwater, and is required by planning regulations for front gardens over 5 square metres in England.

Types of Permeable Paving

• Gravel: the cheapest and most permeable. 30 to 50 pounds per square metre.
• Permeable block paving: blocks with wider joints filled with gravel. 60 to 100 pounds per square metre.
• Porous asphalt: looks like normal asphalt but is porous. 50 to 80 pounds per square metre.
• Grass reinforcement: plastic grids filled with soil and grass. 40 to 70 pounds per square metre.
• Resin-bound gravel: smooth surface, fully permeable. 80 to 120 pounds per square metre.

Benefits of Permeable Paving

• Reduces flooding by allowing rain to soak into the ground
• Required for front gardens over 5 square metres in England
• Reduces runoff into drains and sewers
• Recharges groundwater
• Often cheaper than traditional paving with drainage

Rain Gardens

A rain garden is a planted depression that collects and absorbs runoff from roofs, driveways and patios. It is a beautiful solution that also supports wildlife and reduces flooding. A rain garden is typically 10 to 20 percent of the drainage area, planted with moisture-tolerant plants.

How to Build a Rain Garden

1. Choose a location at least 5 metres from the house, where water naturally collects.
2. Dig a shallow depression 10 to 20cm deep.
3. Improve the soil with compost and grit.
4. Plant with moisture-tolerant plants (iris, lobelia, astilbe, primula).
5. Connect a pipe from your roof or driveway to the rain garden.
6. Mulch with gravel to retain moisture.

Cost: 300 to 800 pounds for a typical rain garden.

Water Butts and Irrigation

Every garden should have a water butt. A 200-litre water butt costs 50 to 100 pounds and provides free, chlorine-free water for plants. Connect it to a downpipe from the roof.

For larger gardens, consider a drip irrigation system. It uses 50 percent less water than a hosepipe and delivers water directly to the roots. A typical system costs 200 to 500 pounds for a small garden, 500 to 1,500 pounds for a medium garden.

Drought-Tolerant Lawns

Lawns are the thirstiest part of the garden. Consider replacing some lawn with:

• Wildflower meadow: needs no watering, supports wildlife. See our wildflower guide.
• Clover lawn: stays green in drought, needs less mowing.
• Gravel or planting: replace the lawn with gravel and drought-tolerant plants.
• Artificial lawn: no watering, but no wildlife value. Divisive.

Cost of Water Conservation Measures

Common Mistakes

• Not mulching. Bare soil bakes hard and loses moisture. Mulch is essential.
• Planting in spring and not watering. New drought-tolerant plants need regular watering for the first growing season.
• Mixing drought-tolerant with thirsty plants. One group will suffer. Group by water needs.
• Fertilising. Rich soil produces soft growth that drought kills. Drought-tolerant plants prefer poor soil.
• Using impermeable paving. It increases runoff and flooding. Use permeable surfaces instead.

Frequently Asked Questions

Do gravel gardens attract cats?

Cats sometimes use gravel as a litter tray. deterrents include citrus peels, coffee grounds, or commercial cat repellents. Planting densely also deters cats.

Is permeable paving more expensive than regular paving?

Slightly more, but it avoids the cost of drainage systems. For front gardens over 5 square metres, permeable paving is required by planning regulations.

How much water does a drip irrigation system save?

About 50 percent compared to a hosepipe. Drip irrigation delivers water directly to the roots, with no evaporation or runoff.

Get Help with Water Conservation

If you want to make your garden in Oxfordshire, Buckinghamshire, Berkshire or Bedfordshire more water-efficient, send us a WhatsApp with photos and we will aim to respond within 12 to 36 hours, Monday to Sunday.

Further Reading

• Best drought-tolerant plants
• Chilterns heatwave guide
• How to mulch properly

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.