[Amilo]

Has anyone ever tried to sterilise compost?

I have one of those metal dustbins with holes and a chimney in the lid and I was thinking of butting a 5 gallon metal drum on top of a slow fire!!!

any thoughts on this?

The reason: I want to make up my own seed compost that will not me contaminated with wild (or otherwise) seeds.

Edited "sterilised" to English spelling from American for search purposes.

[crh75]

I believe that is will get too hot.  You need to pasterise the compost at 80­°C for 30 minutes, this will kill weed seeds but leave some benificial microbes. 

There is information on the Garden Organic website if you are a member.

[JayG]

I've had MANY thoughts on this on MANY occasions! 

I have been known to very carefully microwave small (obviously) quantities of compost, but something on a larger scale which would not be too expensive, dangerous or cumbersome still eludes me.

I guess the trick is to have the right amount of heat and wetness for the steam to permeate the whole container before the bottom dries out and burns - I don't think it's something you could light and leave. 

My "designs" have never got further than eyeing up my mostly-unused steam wallpaper stripper and trying to figure out how to connect it up to my daleks without doing someone (me!) a mischief!

(If anyone has made a home-made soil steriliser that works please post a picture - the more Heath Robinson the better!) 

[pdblake]

Would a metal container full of water on top of the incinerator, then the compost in another metal container on top, but with fine holes drilled in it, work? Kind of like a veg steamer on a cooker.

[Amilo]

I have heard of some one using a steam cleaner to bring the temperature up in a sack of compost but I feel that this will wash away to much of the de-solvable items. Maybe I could my fire to heal some water the plunge a sack of compost into the hot water.

[pdblake]

Scald it, you mean?

Wouldn't you do just as well putting it in a conatiner with drainage holes in and pouring a kettle of boiling water over it (or as many as needed)? It would probably have the same effect and avoid you scalding yourself as well. Wouldn't want to think you'd lobbed a sack of compost into a tub of boiling water and sterilised yourself as well

Saying that, wouldn't that leach as much out as steaming it?

[crh75]

You can buy them from this website.  This may give you an idea of what you could make (way beyond me!)

http://www.thermoforce.co.uk/soil_sterilisers.htm

[Amilo]

Scald it, you mean?

Wouldn't you do just as well putting it in a conatiner with drainage holes in and pouring a kettle of boiling water over it (or as many as needed)? It would probably have the same effect and avoid you scalding yourself as well. Wouldn't want to think you'd lobbed a sack of compost into a tub of boiling water and sterilised yourself as well

Saying that, wouldn't that leach as much out as steaming it?

Possibly, but at least the water could be kept and used to water the growing plants at a later date and in that way re- introduce the missing elements.

At the minute I have in mind to use a 5 gallon drum with a false bottom with water to an inch or so then the steam with have to pass through the compost to get out! The trick will be leaving it long enough to get the temperature up but not running out of water in the bottom and letting the temperature get to high.

[JayG]

If you want to watch a short video of a mad inventor with apparently zero DIY skills constructing a steam soil steriliser which probably doesn't work very well look no further! 

[angelavdavis]

According to Bob Flowerdew at the weekend, he reckoned you should put it in a metal bowl in a 150 degree oven for 20 minutes.  He also recommends, from his personal experience, that you do it without your wife's knowledge 

[gavinjconway]

Garden centres have it in ready made bags for a few quid.... no need to go into steaming, cooking, microwaving .....

Heating is expensive no matter what method you use  - The expense of the heating etc is probably loads more than a few bags from the GC..

[Ema]

all my homemade compost that I've bagged up for the Lottie has slugs in it

[angelavdavis]

all my homemade compost that I've bagged up for the Lottie has slugs in it

Are they teeny weeny ones Ema?

If not, sieve it?

Else, treat it with nematodes when the weather warms up? 

Or spread it out on a tarp on a dry, mild day for the birds to lunch on, then collect it up again?

Heating is expensive no matter what method you use  - The expense of the heating etc is probably loads more than a few bags from the GC..

I must admit, this exact thought crossed my mind when I was listening to him.

[ilan]

Have you thought of filling some seed trays with it putting some place nice and warm and after a week most of the weed seeds will have germinated . simply pull them out I even do this with multi purpose as not only does it get the soil up to temperature  but a lot seems to contain viable seeds 

[fatcat1955]

Have you ever thought of buying in compost from the garden centre. 4x50 litre bag's for £12 Try heating that lot up and see how much it cost's.