Which? Compost reviews

Just been reading Which? magazine's reviews of the performance of different composts for growing seeds and young plants.

Top is Arthur Bower's seed and cutting compost following by 3 different Verve(B&Q) composts -  grow bag then sowing and cutting then multipurpose. Interestingly and as they say 'disappointingly' all the worthy Best Buy  composts for raising plants in are peat based - though the percentage for each varies!

                                                                                         test score

Arthur Bower's seed and cutting compost is 95% peat                91%

Verve Grow your Own Growing Bag 55% peat                             91%

Verve Sowing and Cutting Compost 75% peat                             89%

Verve Multipurpose Compost  58% peat                                      88%

Any comments, experiences, recommendations?

Thought peat based compost was a bad thing...?

There's a long thead about composts, that mentions the Which report, here:

http://www.gardenersworld.com/forum/fruit-andamp-veg/the-best-multi-purpose-compost-this-year/5249-2.html

Lyon Greene wrote (see)

Which? have been researching the issue, systematically. Their results are published in the January/February issue of Gardening Which. I haven't seen the full report, only a summary of their results...

27 brands were tested, for seed-sowing and raising young plants.

Three brands have been selected as 'best buy'. They are all peat-based...

• Sinclair’s J Arthur Bowers’ Seed and Cutting Compost
• B&Q’s Verve Grow Your Own Growing Bag
• Verve Seed and Cutting Compost and Verve Multipurpose Compost.

 

Next, also recommended, though not 'best buys'...

• Westland Jack’s Magic all Purpose
• Westland Gro-Sure Seed & Cutting
• Levington John Innes Seed compost.

 

Best peat-frees, but not as good as the peat ones...

• Miracle-Gro Expand n’ Gro
• Vital Earth Multipurpose compost.

 

If anyone subscribes to the magazine they might have some more details, about how good, or bad, all the others were. I don't know which brands came bottom.

But we don't know the details of the tests, nor which brands should be avoided, and why.

It's a job to know which one to buy this year. If last years examples are anything to go by, I just hope it's better quality, as some of the 'stuff' they called compost was little more than recycled rubbish! 

agree ddoris. Almost half a brick appeared in one of mine and loads of plastic.  I wonder when the review was done. Until a few years ago I rated Arthur Bowers more highly than I would now.

A little more detail to answer the questions above - The survey appears in the current Jan/Feb 2013 Which? garden magazine. The survey was conducted from spring 2012 to find the best buy composts for growing seeds and young plants.

They tested 27 widely available composts - 18 peat based, 9 peat free and asked  mystery shoppers to buy them from 4 different regions in the country.

First they tested the handling and texture of the compost for its suitability for small seeds.

They then tried to raise 12 pots of marigolds and basil seeds from each compost ( 3 from each bag bought  from the 4 different areas in the country) Apparently basil does not germinate well if there is a high level of dissolved nutrients in the compost and marigolds will not thrive if the nutrient levels are too low! They counted germinated seeds and the size and quality of the seedlings.

Then they tested for growing on young plants and seedlings - 20 snapdragon and 20 tomato seedlings were potted up in each compost. Again snapdragons struggle if nutrient levels are too high and tomato don't thrive if they are too low. They were grown on without feeding until the largest were ready to be planted out. All plants were rated on size, quality and leaf colour.

They state that although grow bags are not intended for using to raise seeds  they tested them as some people do use them for this purpose as they are so cheap.

Brands tested included Westland, Bulrush, Verve(B&Q) New Horizon, Levington, Miracle gro, Homebase, Vital Earth, Arthur Bower's 

The best peat free compost was Miracle - Gro concentrated enriched compost with  a test score of 73% with Vital Earth  multipurpose compost 2nd with a test score of 65%

Hope this helps

 OOps meant to add - they only gave the results for 22 composts as the other 5 have been reformulated for this year, the ones listed have not.

Bottom on the peat list was Westland multipurpose, 70% peat and a test score of 59% and Verve John Innes seed compost, 50% peat and a test score of 48%

The botton 2 peat free were both grow bags - New Horizon organic & peat free and Verve grow your own peat free - both with a test score of 34%

Westland (worst MP) is the brand stocked at Wyevale, and some other chains. I've just bought a bag of their John Innes. Their seed compost was well rated.

At many GCs it's Hobsons Choice which brand you get. Unless you're prepared to go somewhere else, which may involve travelling a long way.

I'd really like to see GW cover this subject. Buying compost is an item of regular expenditure for many gardeners and it's important to know if the brand really matters.

discodave wrote (see)

Thought peat based compost was a bad thing...?

Peat is very good for plants as it soaks up excess water and this prevents plants from rotting, hence it is great for young plants and seedlings.

As peat takes time to accumulate it is seen as bad for the environment to use it, even though it has been used for millenia as heating and soil improvement.

as a novice veg grower.gonna stick with peat compost