Seed compost

[LeifParticipant]

I use peat free compost, as I know the damage that peat extraction can do to sensitive wildlife habitats. Anyway, this year I sowed seeds in beds with a 4″ layer of peat free compost, and in modules in a coldframe. The seeds in beds all came up, including the salsify, parsnips and root parsley in 2-3 weeks. Leaks were a bit slower. The beetroot and cabbage in the coldframe popped up in a week or two. The first coldframe leaks appeared after 3 weeks. 7 weeks on and one tray is 80% up, the other is 20% up. As an experiment I subsequently sowed some leaks in a peat based John Innis seed compost. After 2 weeks the first leaks appeared in the coldframe modules, a few days later and about 50% are up. The leaks in outdoor modules are not up yet.

So, the New Horizons and Vital Earth composts are unsuitable for leaks. And a coldframe significantly speeds leak germination. I think the problem is that the peat free composts are too coarse and woody, and dry out too quickly in the coldframe, so they are either sodden, or dry. The peat based compost holds water far better, providing a much better germination environment.

Has anyway found a good peat free seed compost? I wonder if I left the peat free compost for a year to break down properly, would it be better?

[charlesModerator]

Leif this sounds all too familiar, its not good that some peat free composts are sold on the “peat free” tag without being much good, and it is costing gardeners a lot.
However I suggest you look for Melcourt who have been researching and producing wood-based composts for over a decade. Conscientiously I may say, which should go without saying!
Melcourt consistently do well in the trials run by Which? Gardening.
West Riding’s compost is now half based on wood and is as good as their eco-peat based. But you need to buy a lot to get a good price.
Best of luck.

[LeifParticipant]

Thanks Charles, apparently the local garden centre stocks their peat free compost, so I will try to get some this season.

[LeifParticipant]

I thought I’d update this post. I followed Charles’s advice and bought some Melcourt SylvaGrow. The nearest garden centre stock it. It is a fine compost with a spongey water absorbant texture. I’ve only tried it with basil seeds, but it certainly holds moisture very well, does not dry out anything like as quickly as New Horizon peat free compost, and has a good free flowing texture, with no large woody bits, so initial impressions are that this is a high quality product and a viable peat alternative. They state that it has no green waste as well as no peat. It is not cheap, but for fussy seedlings such as leeks, it’ll be worth it if works as well as I think it will.

[RhysParticipant]

Charles/Leif

My experience with germinating leeks this year has been this: the ‘MPC’ from a local garden centre was rather woody and the plants germinated OK indoors in a deep rectangular container. However, they struggled the first 4 – 5 weeks after appearing and benefitted very greatly from two seaweed liquid feeds about 3 weeks apart.

Now, however, the past 3 weeks they have really thrived and shot on and are looking perfect as they become ready to transplant.

As leeks need 8 – 10 weeks prior to transplantation, it may be that balancing optimum food for germination and for growing on may need to be balanced with external food supplements, unless you happen to hit on a great MPC for leeks.

[LeifParticipant]

Thanks, I’ll give the leeks a dose of feed. Yes I think the issue with most of these peat free composts is that the wood is not composted enough, and it is too large, so you end up with a very airy mix that dries out quickly, and which probably deprives the seedling of nitrogen.

[charlesModerator]

Leif, thanks for the Melcourt feedback.
And yes Rhys leeks are often tricky to start but can stage impressive recoveries!

[LeifParticipant]

Thanks again Charles. I will definitely be using this for my chillis and courgettes next year.

[LeifParticipant]

I just found this:

SylvaGrow Peat-free All-purpose Compost Awarded Two Best Buys by Which? Gardening* – and it’s the First Peat-free Compost to be Endorsed by the Royal Horticultural Society (RHS)

[Author]

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