Miracle Gro MPC - avoid!

What fertiliser do you add @gks
Do you add lime.

 

A bit like roll your own....

 

I use Yara PG mix fertiliser plus mag lime. White moss peat tends to have a lower pH value than darker peat, so I have to add extra lime to account for it. Jiffy uses Baltic peat but they also blend both white and the darker peat in their mixes.

 

I'm no scientist but I always understood that woody waste uses up nitrogen in the process of breaking down. Would this perhaps account for the poor performance of some current composts, if the manufacturer doesn't add extra to compensate? Just once I bought a pallet of bags from a manufacturer 30kms from here. Highly recommended by French neighbours. That was the one that killed plants within days of them being re-potted into it It turns out that all the wood waste from the huge pine forest industry to the south and west is / was used as a 100% substitute for peat. Perhaps less so now that they manufacture wood pellets for burners which is the latest fad .
That was also the year that I turned out up to 50 larvae per pot of a wood-eating beetle whose babies are particularly fond of begonia tubers
Didn't the RHS do a U-turn on banning the use of peat when it was discovered that a lot of the 'excitement' over it's sustainability was based on faulty data? I know they did extensive trials on the substitutes and admitted that none of them were as good for growing plants.

 

That's interesting @gks . Is the wood fibre mixed in fresh without composting it first? If so, that would explain why so many bagged composts are very fibrous these days and why texture seems to get much finer if you store it damp for several months. Also why, when I use it for potted plants, by the end of the season the level has dropped considerably with fibrous woody bits only left on the surface where it's exposed to the air so not permanently damp. The wood fibre breaks down in storage/in the pot. Perhaps good for short-term planting, which I suppose is what commercial growers mostly want.

 

If they are not adding nitrogen or enough, then there will be nitrogen deficiency, more so when the percentage of wood fibre is greater.

Was your issue nitrogen deficiency or was there any pathogens in the pine, which might not of been composted properly.

All compost manufacturers were contacted regarding what substitutes we were using, percentage, where it was sourced etc etc. due to these pathogens they have discovered. I replied and was very open and in return I was contacted by phone from Audrey Litterick, a soil scientist. She is not supportive at all with this peat ban and how we are having to go down the green waste and wood fibre route. Like myself, we agree that coir is really the only option, but then we are not cutting our carbon footprint which then makes a mockery of the peat ban.

We were going down the route of incorporating coir in to our mixes 20+ years ago, starting with 10% and increase it by another 10% every 2 years, we were about to get up to 30% when the financial crisis in 2008 caused the GBP to nosedive. Coir back then was financially viable as we were always averaging $1.8 to sterling and it has never come close to that since. Since then we have had the referendum and Liz truss disastrous budget, along with Covid which caused International shipping to go through the roof it makes coir very volatile to price spikes.

The carbon footprint might end up being the least of governments problems, the way they are going. The younger generation are less likely to want to have a career in the horticulture and agriculture sectors due to these policies governments want to impose.

 

I get my wood fibre from ICL who only manufacture growing media for the commercial sector. The fibre is fresh, I could buy it in already blended with peat, but I prefer not to. They use steam and rollers to make the wood fibre, the fibre makes up bulk of the mix, there is woody bits but nothing more than I have seen in composted bark.

I agree, you will see a noticeable shrinkage when there is a high percentage of wood fibre. This will not be an issue with commercial growers due to the quick turnaround of plants. For outdoor planting in containers, I would be recommending john innes composts, I know there is retail multipurpose compost with added JI, but I don't know what percentage they use. In the past, I said a good compost for outdoor planting was 50/50 John Innes to multi-purpose. Now with more wood fibre being incorporated, I would recommend 75/25 John Innes to multipurpose, which should reduce shrinkage.

 

Thanks for your very informative posts, gks. It's very interesting to have the info from the horse's mouth

 

I had lots of wood shavings available to me years ago And I thought it might be worth trying as a soil improver, struggling with clay at the time, it didn't work and never tried it again.

Unless the wood waste is rotted its just adding bulk and not, IMO, doing anything useful to the compost, in fact probably the opposite.

 

Back to the horses bum.... @Fat Controller I'm sure you will know that some of the horse manure dries out in balls, but is still very useful. I opened one of the Livingston MPC this afternoon to compare with the miracle gro and have to report there is not much in it. It perhaps is a little finer and not so much wood apparent. I'll either use the Levington or Supagrow so called "farmyard manure" that was quite fine for seedlings or buy seed compost. I use very little for this as I grow few plants and always add to it depending on the plant/seeds. The MPC like I've said in mainly topping up beds.

 

I worked with horses for a large part of my life, so when I moved to this property [11 years ago] which had no garden- just slabs and gravel, and compacted grass, I brought home a good load of manure. All from stabled animals [ not field ] for creating new beds.
It's great stuff, but if I was using droppings from a field - ie with no ther medium mixed in, I'd add it to the compost bin to break down, or put it on a site that wasn't going to be used for a while, just as I would with newer material that had straw or shavings.
Most people use shavings now, rather than straw. Straw gets eaten too often, and is always a bit variable. If animals are mucked out properly [that's the key] then there shouldn't be more shavings than manure, not the other way round.

 

Not a scientific sample by any means but I'm about 2/3rds of the way through my first bag of Erin Excel MPC and there are no hard lumps or half branches (OK, slight exaggeration) in it. Consistent composition throughout.

 

Thanks for replying@gks . Good to know that the shrinkage is to be expected and not me doing something wrong
I've taken to using bagged topsoil and my home-made compost (sieved if it's a twiggy batch) mixed with bought potting compost, roughly 1/3 each, for anything that's going to be in a container for more than a couple of months, plus maybe some grit if I think it's a plant that wants sharp drainage. Needs feeding from fairly early on, or slow-release granules added, but it seems to be working better than straight MPC (of the types that I can get locally at not-too-great expense).