Soil Mix for a bog garden?

[Dragonyka]

I was reading 'Rock and Water Garden Expert' (which I've bought thanks to a recommendation on here) that the soil mix for a bog garden should be 3 parts top soil, 3 parts peat and 1 part grit.

I have absolutely no intention of putting peat in it - I try my best to avoid ordinary compost with peat in - so the question is what should I use instead?

Thanks

[Kayleigh]

Don't worry there are lots of peat free compost on the market that will work just as well even garden compost from your own bin but this may contain weed seeds..

[Dragonyka]

So it's ok for me to just use ordinary compost? I'd somehow picked up the idea that a special soil mix was needed. (Doh!)

[Kayleigh]

If its in a bog garden and not attached to a pond it should be OK as you wont have a problem with nutrients as you would if you threw compost in a pond.
If on the other hand it is connected to the pond then this would cause a problem with algae bloom.
I think charcoal helps keep the soil from going sour as it going to be wet most of the time.

[Malcolm Banks]

I filled mine with a mixture of top soil and aquatic soil (60:40), it is connected to the pond and is now approaching it’s fourth season with both pond and bog appearing to be functioning OK. The intentional contact between the two must lead to an increase in nutrient flow from the bog to the pond, but I guess the relative sizes of pond and bog, and perhaps the size of the connecting aperture that I have, must allow the pond to absorb this increase and still remain relatively stable.
I didn’t add any compost or peat to the bog. The aquatic soil is expensive and according to some, unnecessary, so in a large bog could be prohibitively expensive.
M

[Dragonyka]

The way I've done it is so that the highest level of the bog garden is lower than the pond, but water can overflow from the pond into the bog. The bog is, roughly, a triangle with 2 sides about 1.5m long, so doing a 60:40 mix of soil:aquasoil would probably be pretty expensive - even though I've found out that you can get it at B&Q for £3.60 for 20L (which is considerably cheaper than the £5.50 for 8L that I'd seen before!)

As the nutrients shouldn't be able to flow from the bog into the pond would I be ok just filling the bog with the topsoil I've dug out?

[Malcolm Banks]

Originally Posted by Dragonyka

The way I've done it is so that the highest level of the bog garden is lower than the pond, but water can overflow from the pond into the bog. The bog is, roughly, a triangle with 2 sides about 1.5m long, so doing a 60:40 mix of soil:aquasoil would probably be pretty expensive - even though I've found out that you can get it at B&Q for £3.60 for 20L (which is considerably cheaper than the £5.50 for 8L that I'd seen before!)

As the nutrients shouldn't be able to flow from the bog into the pond would I be ok just filling the bog with the topsoil I've dug out?

Yes that's what I did for my bog garden, I lowered the rim slightly relative to the rest of the pond. I filled the bog garden with topsoil and it appears to be working fine. (cf the bog which is permanently inundated to the same level as the pond, but since it slopes upwards into the rockery it has a range of depths of soil above the waterline) Since I built the pond I bought a 1200 litre water butt and top the pond up from time to time if it is getting too low (and the bog gardens are not being fed). I did some testing and lowered the rim a little more after first filling, since at first the pond had to be too close to overflowing elsewhere before it overflowed into the bog garden.
Anyway, sounds as if your project is coming along nicely, keep the pics coming.
M

[tom00_uk]

use the top soil on the plot to grow veg, use the subsoil in the bog garden.

[davecatt]

Originally Posted by Dragonyka

I was reading 'Rock and Water Garden Expert' (which I've bought thanks to a recommendation on here) that the soil mix for a bog garden should be 3 parts top soil, 3 parts peat and 1 part grit.

I have absolutely no intention of putting peat in it - I try my best to avoid ordinary compost with peat in - so the question is what should I use instead?

Thanks

Dose your book explain why you should use that mixture?

If its to increase the water holding capacity of the soil,then any organic matter will do,mix straw or grass clippings in with the soil. The more organic material the greater the moisture retention.

If you also need a low ph then use acidic organic material such as pine bark chippings (available at most garden centres),bracken and heather will also do the trick.
Dave
Edit
If you have access to leylandii hedge clippings they also have a low ph. I'd also suggest a higher percentage of acidic organic matter to top soil. Continual dampness will eventually increase the acidity of such materials as they break down so it may be advisable, if the ph decreases significantly enough, to add straw or grass clippings occasionally.

[Dragonyka]

Originally Posted by davecatt

Dose your book explain why you should use that mixture?

If its to increase the water holding capacity of the soil,then any organic matter will do,mix straw or grass clippings in with the soil. The more organic material the greater the moisture retention.

If you also need a low ph then use acidic organic material such as pine bark chippings (available at most garden centres),bracken and heather will also do the trick.
Dave
Edit
If you have access to leylandii hedge clippings they also have a low ph. I'd also suggest a higher percentage of acidic organic matter to top soil. Continual dampness will eventually increase the acidity of such materials as they break down so it may be advisable, if the ph decreases significantly enough, to add straw or grass clippings occasionally.

Good question - I couldn't remember reading anything specific, so I checked and although it doesn't say specifically why that mixture is recommended it does say "The compost should be free-draining and moisture retentive"

I assume the peat is for moisture retention (but that's a stab in the dark from a novice so please correct me if I'm wrong!) so I'll add some straw (I haven't got as far as mowing the grass yet). Do you think it'll matter how much I add?