Discover the top-scoring composts for sowing seeds, raising young plants and growing plants in containers. Read our guide to find out how to pick a compost that will be perfect for your gardening jobs.
The best compost will provide all the nutrients and support needed for seeds and veg to grow and thrive, while the worst will leave you with meagre crops and feeble plants. But the only way to know if a compost is good or bad is to grow plants in it and compare them – something we’ve been doing for more than 30 years. Many people no longer want to buy peat compost as it’s believed to damage the environment and add considerably to global warming. However, peat composts are still the most widely available composts in garden centres and are preferred by many gardeners.
Best peat-free compost for sowing seeds
The results are updated in late January each year.
Fertile Fibre Seed Compost
Score: 85%
Peat content: 0%
Price: £24 for 60L including delivery
Price per litre: 40p
Healthy seedlings. We have had mixed fortunes with coir composts in the past and many of the pure coir products in this trial didn’t excel. However, this compost appears to have some nutrients that helped our seedlings to thrive. In fact, it scored higher than all other composts in this trial by a good margin. There were excellent germination rates and all the emerging seedlings achieved near-perfect scores on all measures.
Where to buy: Fertile Fibre Company
Best peat-free compost for raising young plants
The results are updated in late January each year.
B&Q GoodHome Enriched Multi-Purpose Compost
Score: 86%
Peat content: 0%
Price: £6.50 for 50L
Price per litre: 13p
As good as peat compost. Most B&Q composts are now peat-free – this one is made from coir, green compost and composted bark. Be sure to buy the ‘enriched’ bag, not the standard multi-purpose, as the latter didn’t score as well. The tomatoes had the highest fresh weight, so while they weren’t the tallest, they were sturdy. The antirrhinums were a good size and flowered well.
Where to buy: B&Q.
Don’t Buy peat-free compost for raising young plants
Thompson & Morgan Incredicoir
Score: 20%
Peat content: 0%
Price: £8.99 for 30L
Price per litre: 30p
No fertiliser. This pure coir compost comes as a block, wrapped in a bag into which you pour 4-5 litres of water to rehydrate the dried product.
Unlike other Thompson & Morgan composts, there is no bag of controlled-release fertiliser sold with this and there appears to be no base fertiliser either.
This meant that our seedlings were unable to grow, but they did remain green and healthy. Liquid feed your seedlings from the time you pot them up if you use this product
Coco & Coir Coco Grow
Score: 19%
Peat content: 0%
Price: £5.99 for 9L
Price per litre: 66p
No nutrients for plants. This coir block has no fertiliser added and is simply pure coir. As a result, our plants quickly ran out of the nutrients needed for healthy growth especially nitrogen, which fuels green growth and phosphorus for roots.
Although the seedlings were still a good colour by the end of the trial, they were among the smallest plants in the trial. In a test to see if feeding makes a difference, we found its best to liquid feed seedlings as soon as they’re potted on if there’s no base fertiliser.
Best peat-free compost for containers
The results are updated in late March each year.
Homebase Peat Free Multi-purpose Compost
Score: 75%
Peat content: 0%
Price: £5.25 for 50L
Price per litre: 11p
Great peat-free for pots. This own-brand compost is a mix of bark fines, steam-treated wood fibre and coir. It contains enough feed for six weeks, which perhaps explains why it got off to such a good start. The potato yield was good at around 920g per pot, with more than 80% of the harvest larger than 4cm across.
The pelargoniums were healthy, but without adding controlled-release feed, flowering tapered off towards the end of the trial. Adding feed showed a marked increase in the plants’ health and the number of flowers.
Where to buy: Homebase
Melcourt SylvaGrow Multi-purpose
Score: 70%
Peat content: 0%
Price: £7.99 for 50L
Price per litre: 16p
Versatile peat-free. Often a Best Buy for patio pots, this peat-free product was also the highest scorer in this year’s compost for raising young plants trial (Feb 21). It’s made from wood fibre, composted bark and coir. It gave us a very respectable harvest of potatoes, an average of 883g per pot, and three-quarters of the tubers were a good size.
Although the pelargoniums flowered less as the summer went on, they were very healthy. Adding controlled-release feed to this compost will keep your bedding plants looking good through to late September. Where to buy: Garden centres.
Best peat composts for sowing seeds
The results are updated in late January each year.
Homebase Multi-Purpose Compost
Score: 79%
Peat content: 50%
Price: £5.75 for 50L
Price per litre: 11p
Good all-rounder. This is Homebase’s peat-based compost, with 50% peat and 50% West+, Westland’s treatment of wood fibre. We couldn’t include Homebase’s peat-free compost in the sowing seeds test as Homebase told us it isn’t suitable for sowing fine seeds. The tomato seedlings scored top marks all round. Germination was patchy on the petunias, but the resulting seedlings were strong and robust. They also held well when grown on for slightly longer.
Where to buy: Homebase
Westland John Innes Seed Sowing Compost
Score: 77%
Peat content: 44%
Price: £6.99 for 35L
Price per litre: 20p
Traditional blend. Perhaps the most conventional compost in our trial, it contains peat, loam and grit, so is as close to the original John Innes recipe you can buy nowadays. It doesn’t have any wood fibre, bark or green compost in it. Both seed types germinated well and didn’t deteriorate over time.
The petunias looked easy to prick out and grow on, and the tomatoes were some of the largest seedlings by the end of the test.
Where to buy: garden centres.
Best peat composts for raising young plants
The results are updated in late January each year.
Westland John Innes Seed Sowing Compost
Score: 77%
Peat content: 44%
Price: £6.99 for 35L
Price per litre: 20p Traditional blend. Perhaps the most conventional compost in our trial, it contains peat, loam and grit, so is as close to the original John Innes recipe you can buy nowadays. It doesn’t have any wood fibre, bark or green compost in it.
Both seed types germinated well and didn’t deteriorate over time. The petunias looked easy to prick out and grow on, and the tomatoes were some of the largest seedlings by the end of the test.
Where to buy: garden centres.
Best peat composts for raising young plants
The results are updated in late January each year.
Homebase Multi-Purpose Compost
Score: 87%
Peat content: 50%
Price: £5.75 for 50L
Price per litre: 11p
Reduced peat blend. This is made from 50% peat and 50% West+, Westland’s treatment of wood fibre. It’s said to have enough feed to last four to six weeks, and this may explain why the plants continued to thrive in our trial. The tomatoes were good plants, being among the tallest in the trial with a high fresh weight. The antirrhinums were the best in the test – tall, with lots of blooms.
Where to buy: Homebase
Best peat composts for containers
The results are updated in late March each year.
Thompson & Morgan Incredicompost
Score: 79%
Peat content: 80%
Price: £14.99 for 70L
Price per litre: 21p
Green compost: No Long-flowering pelargoniums. This has done very well in past trials. It was also a Best Buy compost for sowing seeds and raising young plants this year (Feb 21). However, it has the highest proportion of peat at 80%; the remaining 20% is woodfibre. It’s also expensive. It comes with its own bag of controlled-release feed, but doesn’t contain a base fertiliser. This meant we were unable to test the pelargoniums without feed. The potato yield was the highest in the trial, with an average of 940g per pot, and three-quarters of the spuds were large. Although we didn’t trial this without feed, it was one of the best compared with the pots of pelargoniums with added feed.
Where to buy: thompson-morgan.com
Levington Multi Purpose Compost with added John Innes
Score: 75%
Peat content: 40%
Price: £4.99 for 40L
Price per litre: 12p
Green compost: No Large potatoes. Compost manufacturers are increasingly innovative in how they reduce peat content, and this 40% peat mix is a good example. It also contains wood fibre, top soil, green compost and grit – all of which balance water retention with sharp drainage.
The overall potato harvest was high at an average of 921g per pot, while 83% of the spuds were a good size. This compost has enough feed for eight weeks, so the pelargoniums remained healthy through the trial. However, flowering dropped sharply in the unfed pots after eight weeks, so don’t forget to feed your plants.
Where to buy: Garden centres.
What are the different types of compost?
There are two main types of compost: multipurpose and composts for specific use, such as raising plants from seed or growing plants in patio containers.
Multipurpose and all-purpose composts
Claimed to be suitable for germinating seeds, small seedlings and plants in patio containers, it’s a good general compost, but our tests show that not all are great for all jobs. Look carefully at our results table to find one that is good for all your garden tasks. Multipurpose composts are often cheaper than specific-use composts, but check our Best Buys as some specialist composts can give great results.
Seed, potting and specialist composts
Formulated to optimise plant growth by providing the right conditions to suit the plant at a particular stage in its life, or for certain types of plants such as orchids, cacti or ericaceous plants. They often contain a different mix of ingredients to those found in multipurpose composts.
These include small amounts of sand, grit or vermiculite in seed and potting composts, bark in orchid compost and mostly gravel and sand in cacti composts.
The fertiliser may have been adapted, too. Seeds need very little fertiliser to germinate so like the low nutrient levels of seed composts. Young plants need more to fuel rapid growth, and so a multipurpose compost can be a better choice when you prick out your seedlings.
Ericaceous compost is used for acid-loving plants such as azaleas, camellias and heathers when you grow them in pots. Many have a high peat content. Remember to use an ericaceous feed to keep your plants healthy. You may see composts formulated for veg growing.
These are very similar to multipurpose composts, but may have a slightly different balance of nutrients. Some are excellent, some are less good. Look at our grow bags results.
Specific-use composts tend to be more expensive than multipurpose composts, but in some cases it’s worth paying a little more.
Tub and basket composts
Tub and basket composts are formulated to give the right conditions for pots of summer bedding to grow well. Some contain a controlled-release feed and/or water-storing granules.
Tub and basket composts tend to be more expensive than multipurpose compost, but using a multipurpose compost with a Best Buy controlled-release fertiliser and regular watering will often give a better result.
