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Thanks for the warning @infradig. I will mix in some BFB and maybe some slow-release fertiliser granules when I use it.

 

Salvia seedlings growing in grow more compost which is peat based, I think.
They have stood still for over a month and only starting to green up since I started feeding them.

It's very fine and lacks any fertile IMO.

 

I wonder if these video's of peat slips would of received more media attention if they occurred while harvesting peat for the horticultural sector.

Footage shows landslide at Shetland wind farm - BBC News

Peat slip at Viking's Mid Kames site (youtube.com)

Peat Slippage in Donegal November 2020 (youtube.com)

 

I saw the first one on the news this morning, that last one is really weird to watch the trees on the move.

 

I went over to peat free during 2022 and have been disappointed with the results but am trying to find a best practice in using peat free. One minor success i have had this year is with some new bishop dahlias . About 10 days after planting i added a teaspoon of gromore to each pot and lightly worked it into the top layer. Growth has been vigorous and sturdy unlike the last 2 years where growth has been stunted or stopped. I am also sticking with the same brand of compost rather than chop and change . Its high time the industry gave proper advice on how best to use peat free.

 

Tried the Aldi seaweed enriched compost, looks good has a bit of added perlite compared to their other enriched compost. Used it to repot a chilli and germinate some lettuce so far

 

That is a very valid point, but with going peat free, it is difficult to give advice based on a multipurpose compost. We supply commercial growers with commercial grade growing media and even making a growing media for a specific type of crop, it's still a learning curve.

I have supplied a couple of growers with a peat reduced growing media, pot bedding mix. they said the likes of the dahlias, begonias and impatiens plugs struggled to root. They contacted me saying it was a nutrient issue, yet they had no issues with the Marigolds, Salvias, Alyssum, Antirrhinums etc etc, so if it was a nutrient issue, then why did species thrive and others didn't. With the likes of the dahlias, begonias and impatiens, was it a case of over watering, which we experienced ourselves.

The finer grade of wood fibre that we are now incorporating has a far better water retention than the wood fibre we had previously been using. The problem is, when your using the likes of wood fibre and coir, the surface of the pot tends to dry out quicker, so have we have actually been watering plants that were already damp enough.

I did an experiment, I loose filled a 1 litre pot with peat and did exactly the same with a 50/50 peat and wood fibre mix. I weighed each on scales with a +/- 5 gram tolerance. The pot with pure peat weighed 405g and the 50/50 mix weighed 310g. I then added 400g by weight of water to each and have weighed them at regular intervals over a 9 day period. After 9 days the pure peat weighs 410g but the 50/50 mix weighs 350g, meaning the wood fibre mix has actually retained more moisture, please note this was based on water retention, without nutrients or actually trying to grow something.

However, as you will see by the images below, the pot that had wood fibre incorporated looks more drier at the surface compared to the peat based one. So, going by sight, are we inadvertently over watering, oxygen deprivation to the roots is caused by over watering, which will cause poor germination and poor root development, so lack of nutrients might not be the issue.

My advise, when using peat free or peat reduced, there will be a percentage of wood fibre incorporated, so I would be inclined to water less but more regularly, just because the compost is dry on the surface, it does not necessarily mean the compost is dry at the root level.

By sticking to a brand, you are already going down the right path, depending on what your growing and how, will determine is it an over watering issue or lack of nutrients issue. In future, if your going down the Dahlia route, incorporate some perlite in to one mix and compare it with one without. If growth is vigorous with added perlite, then its not a nutrient issue but a watering issue. If growth is poor in both mixes, then it is a nutrient issue.





Everyone I asked, staff and the general public all were unanimous that the top pot needed watering, when in fact none of them did. It was the mixture of wood fibre and peat that had the better water retention, but the dryness of the surface of the pot would of resulted in watering.

 

This was the problem I experienced using Peat free for seed sowing this year, the compost often looked dry, but waggling the finger usually confirmed it wasn’t. It would have been very easy to over water.

 

Great experiment, @gks!

 

Last winter I almost certainly lost some plants due to over watering whilst they were in the cold greenhouse.

 

Thanks very much GKS.
That is a very expansive answer and i am grateful for the time you have taken in your reply .
Its far from straightforward and as you suggest everyone is trying to adapt with inconsistent results and our summers have been challenging in recent years too which doesnt help when trying to deduce a way forward and i am trying to find that balance of nutrient v water and am coming up short.
I am going to persevere and i know i will continue to get total failures but hopefully it will pay dividends in the long run.

 

I just mix some slow release fertiliser in at potting time I find most of it hardly has any nutrient any way.
Or maybe the addition of wood chippings is robbing the nitrogen.

 

This.
@gks
Is the woodfibre used 'raw' or composted ?

 

Yes, the wood fibre is raw after going through a wet process, steam and boiling water to soften the wood so it doesn't give it a feel of wood chip.

The loads we were getting of the coarser grade the weight of the load was about 12-13 tonnes based on a 140-150 cubic metre load. However, the finer grade is more heavier, moisture, as 150 cubic metres weighed 25 tonnes.

Looking at the image below of the 2 trays of Calibrachoa plants taken on the 29th April, you will see the tray to the left are lush in foliage and just starting to flower, yet the tray to the right are already showing colour but with very poor foliage growth. So, grown in the same batch of my own brand pot bedding mix, then we have to rule out nutrient deficiency. The tray to the left the plugs that arrived late Feb, were all potted within a week, the second tray was from our last delivery of plugs, so a good 4 weeks behind.

In April where we are based, the first 2 weeks was very murky to say the least. With the combination of a big change in the weather and not fully understanding the water retention capability of this wood fibre, we over watered.

I have had people say that the wood fibre is rotting down causing the roots to rot, well to me that is nonsense. Anyone who has any experience in composting knows it takes time to decompose especially if it's a cold composting heap. Composting can be done more quickly to rot down wood chip etc etc, but to do so you need a heap that will generate temperatures 60c + plus to accelerate the composting.

The plants eventually came good, but only my sister and 1 other member of staff were in charge of the watering until they recovered.