Peat free Compost problem

Vermiculite has a large number of layers like filo pastry. When dry, the space between the layers holds air and the vermiculite acts as a heat insulator. This space fills with water when wet, the water is then slowly released as the compost dries.

As I mentioned above, it becomes useless if crushed as the space between the layers is lost. It is okay short-term in compost, but I've found it compresses or delaminates after a while. Coarse perlite is definitely better if the plants are going to sit in the compost for more than a few months.

 

The type used for cavity walls will have been treated by the manufacturer to repel water. When used in insulation boards, sand and cement will be added, it is also fireproof making it ideal for insulating chimney flues, kilns etc etc. Not only is it fireproof it can improve the insulation of masonry bricks by 50%.

 

Well I'm not sure I would want that used as insulation in any area where it might get wet.

I can see the advantages regarding flue pipes etc. Where high temperatures are reached but not with dampness involved.

 

Because of this thread I did a small amount of reading up on vermiculite.
It seems it was at one time, contaminated with asbestos.
Not sure if that only occurred in America, or over here as well.
I think they had it all removed over there.

 

Many years ago I seem to remember an article in a gardening magazine that stated that the vermiculite used in the building trade was quite different to the vermiculite used by gardeners and they should not be mixed.

 

This year is the first year I have used peat free compost & whilst I have no problem with the 'feel' of it & the plants seem to grow well I do have a problem with it drying out much quicker than 'ordinary' multi purpose. I guess compost that contains peat would retain moisture easier. The first brand I used was from Melcourt, which I found better than Hillier's own brand of P/F compost. Saying that with the recent hot, sunny weather, lack of any rain & seemingly constant wind, any soil/compost would dry out quickly!

 

Just to throw this into the peat free arena.

There are a couple of interesting articles in this weeks 'Amateur Gardening' magazine.

The first is a comparison between various peat free and a peat based compost. The peat free Miracle-Gro Premium All Purpose compost out performed all others - including the peat based. The only sting in the tail in the massive price - £4.50 for 10l - as opposed to the 2nd best performer which is £7.99 for 50l (peat based).

The second is a letter from Professor Peter Dobson OBE - in a nutshell - he says there is hysteria around the use of peat. Yes CO2 is released when peat is harvested - but that the plants that grow in it will also absorb CO2 - making the use of peat CO2 neutral.

He works for some outfit called The Queen's College which is in Oxford apprently - so what does he know...

 

Hi @clanless - what was the 2nd best performer(peat based) as most bags we see that were more than 50% peat now seem to contain very little peat.
eg Jacks Magics new formula just says " Low in Peat" so could be any figure ??

 

The trials were not from seed sowing but from plug plants purchased, which were then potted into cells before 12.5cm pots. They go on about leaves were going pale in some of the composts, saying the compost lacked nutrients, really, jumping to conclusions. We found when growing with straight coir, we and others had issues. It was not down to the lack of nutrients but down to nutrients leaching out when watering, we remedied this by adding a percentage of loam to the mix, which the nutrients can stick to. So when you have a compost mix that is mainly wood fibre, are the nutrients leaching out when watering?

By potting these plants and putting them in trays with capillary matting, they are not reporting about water consumption. They should of done equally the same amount of plants without capillary, then water quantity and frequency per plant would of been worth highlighting.
If a brand of compost needs more frequent watering, then lack of nutrients might be down to leaching.

There was also an article at the front of the magazine regarding peat. A Scottish commercial grower wrote asking all AG magazine readers to write to your local MP'S to stop the ban of peat, worth a read.