We tested 22 composts at a well-respected horticultural research establishment. We used each compost to grow cabbage 'Caraflex' and antirrhinum 'Floral Showers' F1 seeds. As each has different needs, a compost that did well in both tests should suit most seeds.
We also used each compost to grow on Begonia 'Heaven Series' plugs (young plants bought by mail order) and tomato seedlings, until the largest were ready to be planted outside.
As some composts will not be on sale in the same formulation in 2016, we have not published results for these, but you will still find results for 17 composts below.
Using the table: The more stars the better. Best Buys are highlighted in red. Test score ignores price and is based on: equal weighting for cabbage and antirrhinum seeds - germination 33.3%, size 33.3%, quality 33.3%; equal weighting for tomato and begonia plants - size 33.3%, colour 33.3%, quality 33.3%
1Based on the 2016 suggested selling price for a 20-litre bag or the nearest size to that sold.
Composts for containers
We tested 24 composts for containers at the same research institute. We chose to grow begonia variety 'Belleconia Rose', a popular bedding plant, and potato 'Sarpo Mira' from May to early October.
This table shows how well our plants did in the composts that are still available to buy in 2016.
Using the table: The more stars the better. Best Buys are highlighted in red. N/S = not specified. Test score ignores price and is based on begonia flowering impact and vigour (50%) and spotato yield, quality and size (50%). Price is based on the 2016 suggested selling price for a 50-litre bag or the nearest size to this sold. Cost per litre has been rounded up to the nearest penny.
Attached Files
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which-compost-seeds.png 51.37KB
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which-compost-raising-young-plants.png 47.03KB
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which-compost-containers.png 55.98KB
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