Multipurpose Compost (MPC) is a flexible, ready-to-use growing medium designed for containers, raised beds, and general soil improvement. While convenient, it has limits — understanding how to use it well makes all the difference.

Pots & Containers

• Fill containers loosely; avoid compacting.
• Water thoroughly after planting.
• Expect nutrients to run low after 4–6 weeks — start feeding then.

Feeding After Compost

Most bagged Multipurpose Composts contain enough nutrients to support plants for around four to six weeks. After that period:

• Nutrients leach out during watering.
• Biological activity is low in peat-free mixes.
• Few contain long-term slow-release fertilisers.

Tip: Begin feeding with liquid or granular fertiliser once growth slows or leaf colour fades. For long-term pots, blend MPC with soil-based compost or add controlled-release pellets at planting.

(See Biological Activity for more on nutrient cycling.)

Mixing with Soil

Blend 25–50% MPC with garden soil to improve structure, texture, and water retention. Ideal for revitalising heavy clay or sandy soils.

Raised Beds & Borders

Use MPC as a top-dressing or soil conditioner rather than the sole growing medium. It enhances structure and adds organic matter but lacks the bulk density of mineral soil.

Longevity

Opened bags lose nutrients and structure quickly. Store in a cool, dry place and use within 6–12 months. Mix leftover compost with garden soil or fresh compost before reuse.

Multipurpose vs Specialist Compost

Type of Compost	Best Use Case	Key Difference vs MPC
Seed Compost	Germination & seedlings	Finer texture, lower nutrients
Ericaceous Compost	Acid-loving plants	Maintains low pH
John Innes Mixes	Long-term containers	Soil-based, heavier, stable nutrients
Multipurpose (MPC)	General use	Balanced but less targeted

Environmental Impact

Peat vs Peat-Free

Peat extraction releases carbon and damages ecosystems. The UK will phase out peat-based compost for amateur use by 2027. Peat-free alternatives — based on wood fibre, coir, and green waste — are now the industry focus.

Carbon Footprint of Bagged Compost

Bagging, transport, and disposal all add to the environmental impact. Buying in bulk, reusing bags, and producing DIY compost reduces waste.

Innovations – Biochar & Circular Economy

Biochar is being trialled as a structural, carbon-positive additive. Manufacturers are also increasing the use of recycled green waste, food waste, and digestates to close the organic loop.

Buying Guide – Choosing the Best MPC

What to Look For

• Peat-free label (where possible).
• Organic certification if needed.
• Added fertiliser duration (typically 4–6 weeks).
• Texture – avoid overly woody or coarse blends.

Top UK Brands (2025)

• Westland New Horizon (peat-free)
• Miracle-Gro Performance Organics
• Dalefoot Composts
• B&Q and supermarket own brands (budget options)

(See Buying Guide – Compost Brands for full comparison.)

Balancing Price vs Quality

Cheaper composts can include poor-quality green waste. Higher-priced options offer better consistency, structure, and long-term performance.

FAQs

Is Multipurpose Compost OK for seedlings?
Yes, but a specialist seed compost gives more uniform germination.

Can I reuse old compost?
Yes, but nutrients are depleted. Refresh by adding fertiliser or mixing with fresh compost.

How long does compost last once opened?
Use within 6–12 months; nutrients and structure decline over time.

Summary – Why MPC Still Matters

Multipurpose Compost remains the cornerstone of home gardening. Although it cannot fully replace specialist composts, new peat-free formulations and biochar-based innovations are making it more sustainable and effective. For general container growing, raised beds, and soil improvement, it remains a versatile choice — now improving year by year.