Compost Comparison

The results are in.

In 2024 many growers have switched to Peat-free compost for the first time due to government legislation on retail compost. As much as I believe peatfree is the way forward I already knew we were heading for problems. There is a huge difference in how peat-free composts react and what is incorporated in these new mixes. Way back at the beginning of March, after a few bad experiences with a couple of my trusted peat-free compost brands. I was interested in exploring more of the composts on the market for home growers in the UK.

I set away sowing 6 cells, with 2 seeds in each i replicated this process for 6 different varieties of cut flowers. I grew these on for 6-8 weeks dependent on variety and recorded the germination results and root development. All of the seedlings were sown and grown in the same place, same heat, and watering routine, and no extra fertiliser was added at any point.

I should state this is not a laboratory and I’ve never professed to be a scientist but I would say that sowing a few tens of thousand seedlings a year for over 10 years means I'm probably an experienced grower. These findings I share are facts from my trials, for you to draw your conclusions. I will however happily share the mix I have settled on at the end of this article, and would appreciate hearing your own experiences in the comments.

Firstly purchase, I purchased all of the composts from garden centres, a farm shop, and directly from a company’s website within the final week of February. The bellow shows the bag literage and price paid for each product.

The next table shows the different germination rates of seeds across the different composts.

*I sowed 2 seeds per cell, for this table, I have counted any germination per cell as 1 point.

Without bias I can say with years of experience, getting my hands dirty in many bags of compost, I realised before I even dropped a seed into some of these brand mixes, that a few would be non-performers. But this wouldn’t be as obvious if it was in the hands of a new grower.

Dalefoot poor root development post germination, Melcourt lack of germination, Rocket fungi growth. Evergreen generally poor germination

Sadly some mixes performed very badly with under 50% germination. The crumbly texture of one mix, produced very poor germination, poor root development and crusted over on the surface, the 2 mixes which contained a lot more wood chips produced very poor germination and weak feelings and the mix with the highest amount of John Innes produced poor termination and dried out very quickly.

Of the four composts performing better none of them had large woodchip fibre in them and none were overly sandy, all held water better, were more stable and did not seem to dry as readily. I would say that even in these composts after the plants had developed true leaves they began to struggle more as the days past and it would have been my opinion that they required some additional feed.

As I have mentioned in previous articles on compost I am currently using a mix of 2 brands as without wishing to sound like Goldilocks some are too sandy some are too fiberous and none seem to have it just right in my opinion. So I will continue growing in a 2>1 mix of Bulrush professional mixed with either Melcourt seed mix or Westland’s seed mix depending on which I can get hold of. But I will always be keeping my eye on how each of these composts change as I know they may not always be the same mix. I also begin to use fertiliser on my seedlings as soon as they germinate.

I hope your seeds germinated this Spring, and you enjoyed this article.

Happy Growing

Suzie