Compost & Soil Highlights
- Calculate exact compost volume for beds, lawns, and containers.
- Master the 2:1 Brown-to-Green ratio for odor-free breakdown.
- Compare Hot, Cold, and Worm composting methods.
- Learn to fix common pile issues like smells and slow decomposition.
Calculate exactly how much compost you need, then learn how to make the best “Black Gold” for your garden.
Compost Volume Calculator
Enter your garden dimensions to get an exact compost recommendation.
Your Compost Requirements
Compost Application Guide by Scenario
How much compost you need depends entirely on what you’re trying to achieve. Use this table alongside the calculator above to find your exact situation.
| Application Scenario | Recommended Depth | Mix Ratio | Best For |
|---|---|---|---|
| New Garden Bed | 2–3 inches tilled in | 25% compost : 75% soil | Building soil structure from scratch |
| Established Garden | 1–2 inches top-dressed | Direct mulch layer | Annual soil amendment and moisture retention |
| Lawn Top-Dressing | ¼–½ inch spread | Direct application | Turf health improvement after aeration |
| Raised Bed Fill | 3–4 inches mixed in | 30% compost blend | Creating a premium growing medium |
| Container/Pot Mix | Up to 30% of total mix | 1 part compost : 3 parts potting mix | Nutrient-rich, aerated container growing |
| Transplanting | Handful in planting hole | Mix into backfill soil | Giving new plants a nutrient boost |
What Goes Into a Compost Pile
Successful composting requires a balance of carbon-rich “browns” and nitrogen-rich “greens.” Aim for roughly 2 parts browns to 1 part greens by volume.
✅ Greens (Nitrogen-rich)
- Fruit and vegetable scraps
- Coffee grounds and tea bags
- Fresh grass clippings
- Plant trimmings (disease-free)
- Eggshells (adds calcium)
- Seaweed and kelp
✅ Browns (Carbon-rich)
- Dry leaves and straw
- Shredded cardboard (no tape)
- Wood chips and sawdust
- Paper bags and newspaper
- Corn stalks
- Hay and dried grass
How to Make Compost Work Faster
Most composting problems come from just three things: wrong ratios, wrong moisture, or lack of aeration. Fix these and your compost will be ready in weeks, not months.
| Problem | Cause | Fix |
|---|---|---|
| Bad smell (rotten egg) | Too wet, not enough air | Turn the pile, add dry browns |
| Bad smell (ammonia) | Too many greens | Add more browns, turn the pile |
| Not breaking down | Too dry or too many browns | Add water or greens, turn weekly |
| Attracting pests | Food scraps on surface | Bury scraps in centre of pile |
| Pile too cold | Too small or too dry | Pile needs to be at least 3x3x3 ft |
Three Rules for Fast Composting
- Balance: 2 parts browns to 1 part greens prevents odour and speeds breakdown
- Moisture: Compost should feel like a wrung-out sponge — damp but not dripping
- Aeration: Turn the pile weekly to add oxygen — this is the single biggest factor in speed
Composting Methods Compared
| Method | Time to Compost | Effort | Best For |
|---|---|---|---|
| Cold (Passive) | 6–12 months | Low — just add and wait | People with little time |
| Hot (Active) | 4–8 weeks | High — turn every 2–3 days | Fast results, kills weed seeds |
| Worm Bin | 2–3 months | Low — feed worms weekly | Small spaces, apartments |
| Bokashi | 2–4 weeks | Very low — sealed bucket | Including meat and dairy |
Frequently Asked Questions
For most garden applications, apply 1–2 inches of compost, which equals roughly 0.083–0.167 cubic feet per square foot. Use the calculator above for your exact measurements.
Cold composting takes 6–12 months with minimal effort. Hot composting produces finished compost in 4–8 weeks. Vermicomposting with worms takes 2–3 months.
Yes. Work 1–2 inches of finished compost into the top 6 inches of soil before planting. Compost acts as a slow-release fertiliser and improves drainage.
A rotten egg smell means the pile is too wet; turn it and add browns. An ammonia smell means too much nitrogen; balance with more browns.
Compost improves soil health but has a low NPK ratio. For heavy feeders, use our Soil NPK Fertilizer Calculator to check if your soil needs extra nutrients.
