How to Make Your Own Compost

The Ultimate UK Composting Guide: Turning Waste into Garden Gold

Key Takeaways

• Save Money: Homemade compost reduces the need to buy expensive bagged potting mixes and fertilisers.
• The Golden Ratio: Success comes from a **50/50 mix** of "Greens" (nitrogen) and "Browns" (carbon).
• Speed Matters: "Hot" composting with a bin can produce results in 4–6 months, while open heaps take 12–18 months.
• Versatile Use: Finished compost is perfect for mulching **raised beds**, improving clay soil borders, or mixing with perlite for **pots and containers**.
• Greenhouse Essential: Using compost improves water retention, vital for thirsty crops like tomatoes grown under glass.

Composting is often called "black gold" by gardeners, and for good reason. Whether you are growing tomatoes under glass, filling large raised beds, or cultivating a vegetable patch in open soil, homemade compost is the single most effective way to supercharge your garden.

For vegetable gardeners, it solves three major problems: it feeds hungry crops, improves water retention in pots and containers, and saves a fortune on bagged compost.

In this updated guide, we explore how to make compost fast, the science of the carbon nitrogen ratio composting, and exactly how to use your finished mix in raised beds, containers, and greenhouses.

1. Why Every Vegetable Gardener Needs to Compost

Compost is more than just fertiliser; it is a soil conditioner that adapts to your growing method.

• For Pots & Containers: Compost acts as a sponge. It holds moisture far better than standard soil, which is crucial for container crops that dry out quickly in summer.
• For Raised Beds: Filling raised beds with bought compost is expensive. Homemade compost provides a bulk, nutrient-dense filler that settles well and encourages deep root growth.
• For Soil Borders: It works miracles on difficult ground. It breaks up heavy clay to improve drainage and binds sandy soil together to hold nutrients.
• For Greenhouses: It introduces beneficial bacteria that can suppress common diseases in intensive growing environments.

2. Choosing Your Method: Heaps, Bins, or Tumblers?

The right setup depends on your space and how quickly you need the result.

Top Tip: If you are short on space, check our Mini Greenhouses and compact staging options to maximize your growing area alongside your compost bin.

3. The Perfect Formula: Greens vs. Browns

The biggest mistake beginners make is the "slimy pile." This happens when there is too much wet nitrogen and not enough dry carbon. To fix this, you need to understand the material mix.

The Golden Ratio: Aim for a 50/50 mix by volume.

The Greens (Nitrogen)

• Grass clippings nitrogen source (mix well to avoid matting).
• Vegetable peelings and fruit scraps.
• Coffee grounds (an excellent accelerator).
• Annual weeds (before they seed).

The Browns (Carbon)

• Cardboard for compost (remove tape/staples).
• Woody prunings (shredded).
• Dried leaves and straw.
• Paper and egg cartons.

Need more coffee grounds? Check our expert guide on How To Use Coffee Grounds For Plants.

4. How to Make Compost Fast (The "Hot" Method)

If you want compost ready for the Spring sowing rush, you cannot just pile and leave. You need a High Intent strategy.

1. Chop and Shred: The smaller the pieces, the faster they rot. Using a garden shredder for composting on woody branches effectively increases the surface area for bacteria to work on.
2. Layer It Up: Start with twigs at the bottom for airflow. Then, alternate layers of Greens and Browns as shown in the diagram above.
3. Add an Activator: You can buy a rapid compost activator, or simply use nutrient-rich chicken manure pellets or nettle tea.
4. Monitor Moisture: The pile should feel like a wrung-out sponge. If it's too dry, water it.
5. Turn It: This is crucial. Aerating the pile introduces oxygen, which heats up the bacteria. Turn your heap with a fork every 7–10 days.

You can monitor the temperature using soil thermometers found in our Greenhouse Accessories range.

5. What NOT to Compost (The "Forbidden List")

To keep your greenhouse soil preparation and vegetable beds safe and pest-free, avoid these items:

• Meat, Fish, and Dairy: These attract rats and foxes.
• Diseased Plants: Tomato blight or clubroot spores can survive home composting temperatures. Burn these or use the council bin.
• Perennial Weeds: Bindweed and couch grass roots can survive and re-grow.
• Cat or Dog Waste: Contains pathogens harmful to humans.
• Glossy Magazines: The inks and coatings often contain toxins.
• Can you compost citrus peel? Yes, but in moderation. Too much can make the heap too acidic and slow down worm activity.

6. Troubleshooting Common Issues

Is your compost bin not behaving? Use this table to diagnose the problem.

Symptom	Probable Cause	The Fix
Compost smells of ammonia or rotten eggs	Too much Nitrogen (Green) and lack of air.	Turn the pile and mix in shredded cardboard or paper.
Pile is dry and nothing is rotting	Too much Carbon (Brown) or lack of moisture.	Add water and mix in fresh grass clippings or veg scraps.
Compost bin fruit flies swarming	Exposed food waste.	Cover fresh kitchen scraps with a layer of brown leaves or soil.
Slugs in compost heap	Perfectly normal!	Slugs help break down material. Pick them out before using the soil.
Compost too wet and slimy	Rain getting in or poor drainage.	Cover the bin with a lid or carpet; add dry woody material.

7. How to Use Compost: Specifics for Every Garden Type

When is compost ready? It should be dark brown, crumbly, and smell like damp woodland earth. Once ready, here is how to apply it depending on where you are growing:

For Pots & Containers (The "Potting Mix" Recipe)

Garden compost is often too rich and dense to use 100% undiluted for pots. To create the perfect growing medium on your Potting Bench, mix:

• 1 Part Sifted Compost: Provides the nutrients.
• 1 Part Garden Soil/Loam: Adds structure.
• 1 Part Perlite or Grit: Ensures drainage so roots don't rot in the container.

For Raised Beds (The "No-Dig" Mulch)

Raised beds naturally slump over time as the soil settles. Instead of digging, use the benefits of homemade compost to top them up.

• In Autumn or early Spring, spread a 2-3 inch layer of compost on top of the soil.
• Do not dig it in. Let the worms pull the organic matter down into the bed. This preserves the soil structure and feeds the bed for the season ahead.

For Open Soil Borders (The Clay Breaker)

If you are gardening in the ground:

• Clay Soil: Dig the compost in vigorously. The organic matter forces the clay particles apart, improving drainage and making it easier to work.
• Sandy Soil: Lay it as a thick mulch to lock in moisture before the summer heat hits.

For Greenhouses

Intensive greenhouse growing depletes soil fast. If you grow in border soil inside your Aluminium Greenhouses, treat the beds exactly like raised beds: mulch thickly in Autumn to replenish nutrients lost to hungry tomatoes and peppers.

Making your own compost is the hallmark of a skilled gardener. It closes the loop on waste and provides your greenhouse crops, raised beds, and pots with the best possible start. Whether you choose a simple heap or a high-speed tumbler, the result is always worth the effort.