Experiment - Soilless mixture for raised beds

11 years ago

This is my first post to the GardenWeb Forums. I have learned a tremendous amount from other users recently. I have built a couple of extra raised bed that need to be filled. Unfortuanately Canadian Peat is extremely expensive here in South Africa. I can source compost and vermiculite quite cheaply. So I have initiated an experiment today with different mixes. I have:

1. 1:1:1 of Compost:Peat:Vermiculite

2. 1:0:0 (Only Compost)

3. 1:0:1 (Compost:Peat:Vermiculite, aka no Peat)

4. 1:1:1 (Compost:Coir:Vermiculite, the Coir is Coco Peat, milled relatively fine)

5. 8:2:3 (Compost:Peat:Vermiculite, left over mix)

I put the mixes in into sq feet containers and water well. Couple of hours later I plant some, peas, beets, radishes and lettuce in each container and watered again.

Will post follow-up if anyone is interested to see the results.

Featured Answer

purslanegarden

11 years ago

It's always fun to see others' experiments. I can make the following comments, though.

Peat or coir is often suggested as one of the ingredients to a custom mix, so I think you're fine without the peat since you did not mention problems with coir.

I also remember reading about someone who did grow primarily in compost. He was able to make lots of it, and his compost consistency was such that he didn't need to mix in peat, but it also had good water retention. So in the end, his primarily composted material was his medium for growing his plants, without having to add other components. His plants did fine also. It's not to say everything called compost can be used to do this, but he had done something for a number of years and ended up with his results of whatever he composted regularly and used as a final planting medium.

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Comments (10)

Katie Gooding
11 years ago
I'm very interested to see your results! My favorite part of sfg is the experimentation aspect that so many of us do!
Jacques (MP, South Africa, like zone 9)
Original Author
11 years ago
I will keep you posted Katie. Have you tried any other mixes and if so what were your conclusions?
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Jacques (MP, South Africa, like zone 9)
Original Author
11 years ago
Lettuce to first emerge from the two 1:1:1 mixes after 3 days... That is fast!
Jacques (MP, South Africa, like zone 9)
Original Author
11 years ago
So here are the follow-up on my soilless mixture experiment 15 days since planting:

Above: Compost Only.

Above: Compost & Vermiculite (1:1)

Above: Compost:Coco Peat:Vermiculite in 1:1:1

Above: Compost:Peat:Vermiculite in 8:2:3 ratio.

Above: Compost:Peat:Vermiculite (1:1:1)

Above: Side by side of 1:1:1 (coco), 8:2:3, 1:00, 1:1:1, 1:0:1
aruzinsky
11 years ago
Why no pearlite? I also recommend using rice hulls which are typically used as a replacement for pearlite but not peat moss. For potted plants, I use 1/3 Riceland parboiled rice hulls and 2/3 peat moss.
Jacques (MP, South Africa, like zone 9)
Original Author
11 years ago
aruzinsky, I tried permutations of Mel's mix to see the effect of reducing the peat most since it is expensive here where I live. I will be using perlite for potted trees in due course.
Jacques (MP, South Africa, like zone 9)
Original Author
11 years ago
Here are the final results:

Above: Side by side of 1:1:1 (coco), 8:2:3, 1:00, 1:1:1, 1:0:1
PRO
Deck Pros
11 years ago
Thanks for posting. Looks like the MM wins.
Vireo
11 years ago
I love seeing experiments too--you see a lot of information out there in the permaculture and biodynamic circles but not any experiments to see if various things make a difference. Same with companion planting. I laugh that weeds are still weeds, but now we can call them "nutrient accumulators." :)
So, this looks and sounds like bagged compost, so I'd be interested in the ingredients of the compost. In the Pacific NW of the USA, the compost is overwhelmingly composted bark of conifer trees and it doesn't really compost down very quickly. I wonder what there is in SA? My own compost is great, but I'm still having trouble meeting all my compost needs. I need to do some experiments myself.
Lucky you to be gardening in South Africa. I've been there and it's a beautiful place.