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Best Buy composts for sowing seeds

By Adele Dyer

Seeds are self-contained packages that have everything inside them to germinate and start to grow. They just need fine, well-drained compost. 

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There's a huge difference between the basil seedlings grown in a Best Buy compost and those grown in a Don't Buy compost. 

Best composts for sowing seeds for 2019

A great compost for sowing seeds should have a fine texture that will surround the seeds with everything they need for strong, healthy growth. 

See how all the composts scored by looking at the full results table and see which were Don't Buy composts for sowing seeds. 

Which? members can log in to view our recommendations below. Not a member? Join Which? and get full access to these results and all our reviews.

Compost Our verdict Basil seeds Petunia seeds Score
Compost non-member logo
100%

Outstanding for sowing seeds

Peat content: 100%

This is the first year we have tested this compost, but we wanted to include it as members tell often tell us how good it is. It's made from good-quality peat. 

It couldn't be faulted in the sowing seeds test, with very high germination rates and excellent growth for both the basil and the petunias. 

It was also good in the young plants test, so it might be worth considering for both jobs.

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Compost non-member logo
98%

Great all-rounder

Peat content: 80%

This high-peat compost has been a Best Buy for sowing seeds for the past few years. It's made from peat, mixed with wood fibre. 

It's only available to buy online, so you'll need to pay delivery charges as well. 

All the trays of basil and petunia seeds germinated well and grew quickly to form strong seedlings. 

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Compost non-member logo
93%

Rapid seedling growth

Peat content: 70%

This is the second time we have tested this compost, and it has been a Best Buy compost for sowing seeds both times. It's a peat-rich mix with added loam, rockdust, vermiculite, sand and plant stimulants. 

Germination of the basil and petunia sees was excellent, and it was very even across the trays. The seedlings quickly grew to be larger, stronger and healthier than others in the test. 

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Compost non-member logo
90%

Great germination rate

Peat content: 90%

Price: £6.99 for 60L

Price per litre: 12p

This compost has been a popular choice for many years. It has a very high proportion of peat compared with many composts. Other manufacturers often mix up to 50% wood fibre or bark to make their composts more sustainable. 

The basil seed was a little slow to germinate, but within a week more had germinated than in any other compost. The antirrhinums germinated rapidly and in both cases the seedlings were very healthy. 

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Key

Member Content

How we test seed composts

This year we sowed seeds of basil 'Puck' and petunia 'Express Rose', with 25 seeds of each in quarter-size trays. We grew 12 trays of basil and 12 of petunias for each of the composts we tested. When the majority of seedlings are at the first two true-leaf stage, we count the number of seeds that have germinated and rate the seedlings for size and vigour. 

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