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Quick Answer
Use mushroom compost for alkaline chalk soils and vegetable gardens. Use farmyard manure for heavy feeding plants like roses and vegetables. Use bark mulch for suppressing weeds and retaining moisture on the surface. Cost: mushroom compost 4 to 8 pounds per 50 litres, manure 6 to 12 pounds per 50 litres, bark mulch 5 to 10 pounds per 100 litres.
Mushroom Compost
What it is
Spent compost from mushroom farms. A mix of straw, horse manure, gypsum and chalk. Alkaline (pH 7.5 to 8.0).
Pros
- Cheap and widely available
- Good for alkaline soils (chalk and limestone), ideal for Chiltern gardens
- Breaks down slowly, improving soil structure
- Good for vegetable gardens
Cons
- Alkaline, so not suitable for acid-loving plants like rhododendrons
- Can be too rich for some plants
- May contain mushroom spores
When to use
On chalk soils in High Wycombe, Amersham and Princes Risborough, for vegetable gardens, for soil improvement before planting. Not for rhododendrons, camellias or other acid-loving plants.
Farmyard Manure
What it is
Well-rotted manure from horses, cows or chickens. Rich in nitrogen, phosphorus and potassium. Must be rotted for at least 6 months before use.
Pros
- Rich in nutrients
- Improves soil structure
- Good for heavy feeders (roses, vegetables, fruit)
- Slightly alkaline but less so than mushroom compost
Cons
- Can be too strong for some plants if not well rotted
- May contain weed seeds if not properly composted
- More expensive than mushroom compost
When to use
For roses, vegetables, fruit bushes and other heavy feeders in gardens across Oxfordshire and Buckinghamshire. Dig in before planting or use as a mulch in spring.
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Bark Mulch
What it is
Shredded bark from forestry. Comes in different grades from fine to coarse. Does not add significant nutrients but excellent for mulching.
Pros
- Excellent weed suppressor
- Retains moisture in the soil
- Looks attractive
- Slow to break down, so lasts 1 to 2 years
- Suitable for all plants (neutral pH)
Cons
- Does not add nutrients
- Can rob nitrogen from the soil surface as it breaks down
- Not suitable for digging in
When to use
As a surface mulch on borders and around trees and shrubs in gardens across Berkshire and Bedfordshire. Apply 5cm thick in spring after weeding.
Comparison Table
| Mushroom compost | Farmyard manure | Bark mulch | |
|---|---|---|---|
| pH | Alkaline (7.5 to 8.0) | Slightly alkaline (7.0 to 7.5) | Neutral |
| Nutrient value | Medium | High | Low |
| Best for | Vegetable gardens, chalk soils | Roses, fruit, vegetables | Mulching, weed control |
| Cost per 50L | 4 to 8 pounds | 6 to 12 pounds | 3 to 6 pounds |
| Dig in or mulch? | Dig in | Dig in or mulch | Mulch only |
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Get Help with Soil Improvement
If you need help choosing or applying soil improvers in Oxfordshire, Buckinghamshire, Berkshire or Bedfordshire, contact us on WhatsApp.
Further Reading
- How to improve soil before planting a new border
- Topsoil vs compost
- Chalk soil in the Chilterns
- How to mulch properly and what to buy
In established gardens, soil structure takes decades to build. Avoid deep cultivation near mature trees and shrubs, as their fine feeder roots extend well beyond the canopy.
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.
Sources and citations
This article draws on the following sources. Specific claims are cited inline where relevant.
- CGM field records (2025-08. Site observations from gardens across Oxfordshire, Buckinghamshire, Berkshire and Bedfordshire.
- Royal Horticultural Society (2024). RHS Gardening Advice and Plant Finder. Available at rhs.org.uk.
- Met Office (2024). Regional climate averages, South East England. Available at metoffice.gov.uk.
- British Geological Survey (2024). Soil parent material data for the Chilterns and Thames Valley. Available at bgs.ac.uk.