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Peat-free compost for pots and balconies: how to choose it and use it well

Why peat-free compost matters, what it's made from, how to read the bag, and RHS-backed tips on watering, feeding and storing peat-free compost for containers, window boxes and balcony planters.

For container gardeners, compost is the soil. Every pot, window box and balcony trough depends on what comes out of the bag. More of those bags are now peat-free, and the Royal Horticultural Society (RHS) encourages all gardeners to switch. This guide explains why, what's in peat-free compost, and how to get good results with it in containers.

Why go peat-free?

Peat forms over thousands of years in waterlogged bogs, and the RHS sets out why it should stay there:

• Carbon storage. The RHS says peatlands store over twice as much carbon as all the world's forests combined, despite covering a much smaller land area. Draining and digging peat releases that carbon.
• Slow to form. According to the RHS, it takes 100 years to form just 10cm of peat.
• Flood control and wildlife. Healthy bogs act like a sponge, soaking up heavy rain and releasing it slowly, and they are home to rare species. The RHS states that at least 80% of UK peatlands have been damaged.

There is currently no law banning peat in horticulture. The RHS notes that despite previous government commitments, no legislation is in place, so the timeline to end its use remains unclear. Choosing peat-free is, for now, up to you.

What is peat-free compost made of?

The RHS lists a range of ingredients used in peat-free growing media, including bark, wood fibre, coir, anaerobic digestate, bracken, waste sheep's wool, sustainably farmed sphagnum moss and green waste compost. Each brand blends them differently, which is why two peat-free bags can behave quite differently.

Reading the bag

• Look for the words "peat-free". The RHS warns that if the bag doesn't specifically say "peat-free", it likely isn't. Terms like "environmentally friendly" or "organic" don't guarantee it, as the RHS also points out on its compost choices page.
• Check the Responsible Sourcing Scheme logo. The RHS recommends looking for the Responsible Sourcing Scheme (RSS) logo, which rates ingredients against environmental and sustainability criteria. You can search the RSS website for a compost's traffic-light rating.
• Check the date. The RHS says compost degrades if stored for a long time, and some manufacturers now print a production date on the bag.

Pick the right mix for the job

The RHS's first tip is to use compost designed for the job you're doing: seed and cutting mixes for sowing, followed by multipurpose or potting compost, or specialist mixes for ericaceous (acid-loving) plants, carnivorous plants or houseplants. You may need to try a few brands to find one that suits you.

For balconies, weight matters as well. The RHS's guide to balconies and roof gardens notes that soil (loam)-based composts such as John Innes No.3 suit long-term plantings and dry out less quickly than soilless mixes, but are heavier. On a balcony, lighter soilless peat-free mixes, lightweight containers and placing heavy pots near load-bearing walls help reduce the load.

Watering: the biggest difference

This is where most people struggle when they first switch. The RHS advises: water little and often, and always check by pushing a finger into the compost, because some peat-free composts look dry on top when there is plenty of water lower down. With small pots, lifting them to feel the weight is a good guide.

Importantly, the RHS says its research shows peat-free compost shouldn't need more watering than peat; it needs watering differently. Over-watering because the surface looks dry is a common mistake. Our guide to watering houseplants properly covers the same principles indoors, and micro-drip irrigation can help on a busy balcony.

Feeding

Plants in containers may need feeding differently in peat-free compost. The RHS suggests watching for signs of deficiency, such as pale or yellowing leaves, and adjusting how often and how much you feed. For young plants, it recommends starting a dilute liquid feed as soon as the first true leaves appear. Follow the feed manufacturer's instructions and choose a feed suited to what you're growing.

Sowing seeds peat-free

The RHS says sowing seeds and taking cuttings in peat-free compost may feel a little different if you're used to peat, but is easy with practice. Use a fine seed mix, firm it gently, and keep it evenly moist rather than wet.

Little mushrooms? Don't panic

Small mushrooms sometimes appear on the surface of peat-free compost, especially those containing wood. The RHS says this isn't anything to be concerned about: pinch them off and add them to the compost bin.

Storing and using up compost

• Buy what you need for the season. The RHS advises using compost in the growing season you bought it.
• Store bags somewhere sheltered; the RHS notes that bags left outside for a long time can degrade.
• Share specialist bags with gardening friends so nothing goes to waste.

Don't waste potting compost on beds

If you also have a small garden or raised bed, the RHS advises against spreading bagged potting compost on beds and borders, because a lot of resources go into making it. Save it for pots. For improving soil, use home-made compost, leaf mould or a dedicated soil improver such as composted green waste or manure.

Repotting and reusing compost

Compost in containers slowly breaks down and loses structure, especially in permanent plantings. Some practical points:

• Long-term plants such as shrubs, small trees and perennials in pots benefit from having the top few centimetres of compost replaced each spring, and from repotting into fresh compost every couple of years.
• Old compost from annuals doesn't need to be thrown away. Add it to a compost heap or use it as a mulch around established plants, rather than reusing it for seeds.
• Don't top up with garden soil in containers; it compacts and drains poorly in pots.

Making your own compost in a small space

The RHS encourages gardeners to make their own compost or leaf mould for soil improvement, or to use council garden waste collections if that isn't possible. On a balcony, a small sealed bin or a wormery can turn vegetable peelings and spent plants into a useful soil improver for pots, reducing how much bagged compost you need.

Buying plants peat-free

Many nursery plants are still grown in peat. The RHS suggests asking whether plants are peat-free, using its list of peat-free nurseries, and considering bare-root plants in autumn and winter, which avoid the compost question altogether.

Quick checklist

• Bag says "peat-free", ideally with an RSS rating you're happy with.
• Right mix for the job, and lighter mixes for balconies.
• Water little and often; test below the surface.
• Watch leaves and adjust feeding.
• Use it fresh, store it dry.

Sources and further reading

• RHS: Peat-free advice for gardeners
• RHS: Peat-free compost choices
• RHS: Ten top tips for peat-free success
• RHS: What are the alternatives to using peat-based compost?
• RHS: Greening balconies and roof gardens
• Responsible Sourcing Scheme

Facts and links checked on 21 October 2026. Spotted an error? Tell us and we will correct it.