Bark chips
Long-lasting decorative cover for borders and trees. Best at 5–7.5 cm depth.
Garden Tools
Plan smarter with free calculators for compost, pots, spacing, mulch, watering, and bed layouts. Each tool also has a full guide page with FAQs, tips and related plants.
Full calculator guides
Mulch CalculatorVolume, depth & FAQs
Soil CalculatorBed fill volumes
Compost CalculatorTop-dress amounts
Compost MixGreens, browns & C:N
Raised BedMulti-bed soil totals
WateringSeason & plant advice
Gravel CalculatorPaths & decorative areas
Pot SizeDiameter by plant height
Plant SpacingHow many plants fit
Garden PlannerPlan beds & plant lists
Companion PlantingBest plant pairings
Mulch Calculator
Work out how much mulch you need, then learn depths, types and best practice.
Open full guide →- Calculator
- How to Measure Your Garden
- Types of Mulch
- Mulch Depth Guide
- Mulch Benefits
- Frequently Asked Questions
- Related Articles
- Related Plants
- Other Calculators
Calculator
Enter your bed size and preferred mulch depth to estimate volume and bag counts.
How to Measure Your Garden
- Rectangle beds: Measure length × width in metres, then multiply for area (m²).
- Odd shapes: Split into rectangles/triangles, calculate each area, then add them up.
- Circles: Area ≈ 3.14 × radius × radius (radius is half the diameter).
- Paths & borders: Measure the strip length and average width, then multiply.
- Quick tip: Pace roughly (1 stride ≈ 0.75–0.9 m) for a rough estimate, then refine with a tape.
Types of Mulch
Garden compost
Feeds soil as it breaks down. Ideal for vegetable beds and mixed borders at about 5 cm.
Leaf mould
Gentle, moisture-holding mulch for woodland and shade plantings.
Gravel / slate
Permanent look for Mediterranean and alpine beds. Use over weed membrane where suitable.
Straw / grass clippings
Useful around veg. Apply thin layers and keep clear of soft stems to avoid rot.
Woodchip
Good for paths and around established shrubs. Avoid fresh chip hard against soft stems.
Mulch Depth Guide
| Use | Suggested depth |
|---|---|
| General borders | 5 cm |
| Weed suppression / dry summers | 7.5 cm |
| Vegetable beds (compost) | 3–5 cm |
| Around trees & shrubs | 5–7.5 cm (keep off the trunk) |
| Paths (woodchip) | 5–10 cm |
Leave unmulched space around stems and crowns so plants don’t rot.
Mulch Benefits
- Locks in moisture so you water less in dry spells.
- Suppresses weeds by blocking light to the soil surface.
- Protects soil from heavy rain splash and summer baking.
- Feeds the soil when organic mulches break down.
- Tidies borders with a finished look between plants.
Frequently Asked Questions
When should I mulch?
Spring after the soil has warmed, or autumn to protect roots. Mulch when soil is moist so you seal water in.
Can mulch cause problems?
Yes if piled against stems — it can cause rot. Keep a small clear collar around woody trunks and soft crowns.
Do I need to remove old mulch?
Usually no. Top up organic mulch as it settles. Refresh bark every 1–2 years if it thins.
Is cardboard under mulch okay?
Yes for reclaiming weedy ground. Wet cardboard, overlap edges, then cover with compost or woodchip.
How many bags will I need?
Use the calculator above. As a guide, 1 m³ is roughly fourteen 70 L bags (or twenty 50 L bags).
Related Articles
Related Plants
These favourites benefit from a moisture-locking mulch in borders and beds.
Soil Calculator
Estimate soil for raised beds, then explore sizes, mixes and drainage tips.
Open full guide →Calculator
Enter your raised bed or border dimensions to estimate how much soil or compost mix you need.
Raised Bed Sizes
| Bed size | Typical use | Suggested depth |
|---|---|---|
| 1.2 m × 1.2 m | Small patio / starter bed | 20–30 cm |
| 2.4 m × 1.2 m | Classic kitchen garden bed | 25–40 cm |
| 3 m × 1.2 m | Long veg row / cut flowers | 25–40 cm |
| 1 m wide any length | Easy reach from both sides | 20–35 cm |
| Deep bed (60 cm+) | Root crops, poor native soil | 45–60 cm |
Keep beds no wider than about 1.2 m so you can reach the middle without stepping on the soil.
Soil Types
Topsoil
Bulk fill for raised beds. Choose screened, weed-free topsoil as the main volume.
Garden compost
Adds organic matter, moisture and nutrients. Blend into beds rather than using alone.
Multi-purpose compost
Handy for containers and topping up. Less ideal as the only fill in large beds.
Loam-based (John Innes style)
Heavier, stable mix for long-term planting and fruit bushes in beds or large pots.
Ericaceous compost
Acid-loving plants such as blueberries, camellias and rhododendrons.
Grit / sharp sand
Improves drainage in heavy mixes — especially useful for Mediterranean herbs.
Compost Ratios
Simple blends for filling raised beds (by volume):
- General veg & flowers: 50% topsoil · 30% compost · 20% well-rotted manure or leaf mould
- Heavy clay native soil underneath: 40% topsoil · 40% compost · 20% grit
- Herbs & Mediterranean: 60% topsoil · 20% compost · 20% grit
- Shade / woodland style: 40% topsoil · 40% leaf mould · 20% compost
- No-dig top-up: 5 cm compost on the surface each year
Need bag-by-bag mix maths? Try the Compost Mix Calculator.
Drainage Tips
- Raise the bed: Even 20 cm helps on wet ground; 30–40 cm is better for root crops.
- Don’t seal the base: Leave soil-to-soil contact or drill drainage holes in lined beds.
- Roughen compacted ground: Fork the native soil before filling so water doesn’t perch.
- Add grit for heavy mixes: Improves air spaces so roots don’t sit wet.
- Water after filling: Settle the mix, top up any dips, then mulch the surface.
FAQ
How deep should a raised bed be?
20–30 cm works for salads and many flowers. Aim for 30–40 cm for most vegetables, and deeper for carrots or poor native soil.
Can I fill a bed with only compost?
Not ideal. Pure compost can dry out, slump and lack structure. Blend with topsoil for a longer-lasting bed.
How much does 1 m³ of soil weigh?
Roughly 1.2–1.4 tonnes when moist. Our calculator uses about 1.3 tonnes per m³ as a planning guide.
Should I put rubble or bottles in the bottom?
No — that reduces useful soil depth. Fill with proper mix and fix drainage by raising the bed or improving the base soil.
How often do I refill?
Organic mixes settle. Top up with compost each spring; expect to add a few centimetres after the first year.
Watering Calculator
Follow the steps below for season- and weather-aware watering advice.
Open full guide →Calculator
Answer three quick questions — season, current weather, and plant type — to get a clear watering plan for your garden.
StartWatering Advice
Choose season, weather and plant type, then press Get Watering Advice.
Common Mistakes
- Little and often: Shallow sprinkles keep roots near the surface. Water deeply, less often.
- Watering leaves: Wet foliage overnight invites disease. Aim at the soil around the roots.
- Ignoring pots: Containers dry out much faster than borders — check them daily in hot weather.
- Watering at midday: Morning is best so plants can use moisture before evening chill.
- Guessing by the surface: Scratch 2–3 cm down; if soil is moist underneath, wait another day.
FAQ
How do I know if a plant needs water?
Check soil 2–3 cm below the surface. If it feels dry, water thoroughly until moisture reaches the root zone. Wilting can also mean heat stress, so always check the soil first.
Should I water every day in summer?
Not usually for established borders. Deep watering 2–3 times a week is better. Containers, seedlings and thirsty plants may need daily checks in a heatwave.
Is rain enough?
A light shower often isn’t. Aim for the equivalent of about 2.5 cm of rain per week in the growing season for most beds — more for veg and containers.
Can I overwater outdoor plants?
Yes. Soggy soil starves roots of oxygen and encourages rot. Reduce watering in cool, wet weather and improve drainage if water sits on the surface.
What about newly planted plants?
Keep them consistently moist for the first growing season while roots establish. Water deeply after planting and check more often than mature plants.
Garden Planner
Plan garden size, conditions, plant lists, recommendations and layout.
Open Garden Planner →Build a full garden plan with plant recommendations from the live plant database, then save it for later.
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