Sterilising seed compost

[Guest]

Bill, on Haworthia seed raising have you looked at Joyce Cocozza's site?



And she uses Cheshunt Compound!

Mike.

[iann]

Cheshunt Compound is truly nasty stuff, its amazing anything at all manages to germinate in it. It is a mixture of 11 parts Ammonium Carbonate with 2 parts Copper Sulphate.

Copper Sulphate is a well know algicide and fungicide although sufficiently toxic that it has mostly been replaced for largescale use by other copper compounds. Copper Sulphate is also a contact herbicide, although it is mainly effective against aquatic plants. It is relatively insoluble in alkaline conditions such as when mixed with Ammonium Carbonate.

The chemists among you will have spotted that there is no such compound as Ammonium Carbonate, but that is the name used for a mixture of Ammonium Hydrogen Carbonate and Ammonium Carbamate. Highly alkaline, pH about 9.5 in a saturated solution. Breaks down completely giving off Ammonia gas at about 60C, so don't try microwaving this stuff!

[Vladimir]

I use ceramic clay for my seeds. It may be called ceramis in Europe, here in US it is turface. It was backed at 2000c or so, does not need any sterilising off the bag, and cooking at 220C definitely would not change a thing about it. It also does not support spreding of any fungi if they start around a seed or two.

[Phil Hocking]

I have heard that Chinosol can also inhibit germination of some seeds, although obviously not all (otherwise none of us would have any seedlings). If we assume that it is a germination inhibitor, how about giving the seeds a few days head start before applying the Chinosol? That way they will have absorbed the moisture they need for germination and the process will be underway before any Chinosol gets into the seed. Maybe none will get in anyway if the seeds have absorbed enough water, and the stuff will do its work in the compost where it is supposed to. One could perhaps pre-germinate the seeds on a paper towel with sterilized water for a few days, then sow into the Chinosol treated compost.

While looking for advice on the Internet re the 'baggie method' I noticed that some recommend the use of dilute hydrogen peroxide. Has anyone tried that?

Somerset Phil

[Phil_SK]

On another forum someone (not based in the UK) posted that they sterilised the seeds by shaking them with a [dry powder] fungicide based on thiram. Nobody knew of an equivalent available in the UK. Do any of you do something like this? if so, with what?

[jamesfe]

I was just about to bake some soil for seedlings , but now I'm hesitate to . I think I'll gamble on just trying to pick out the nasty.

[jamesfe]

has anyone here used neem as a fungicide. maybe I'll skip the bake in oven , or microwaving and just soak the pots and soil in neem oil and water.

[Phil Hocking]

I think it is worth baking the compost, the trick being to keep it moist so the temperature doesn't get too high, but bake it long enough so the heat goes right through. The cake analogy is a good one - it will burn if it dries out and will be squidgy in the middle if you don't bake it long enough. If successful you can leave your seedlings in their bags for a year and nothing will trouble them. Some might develop algae or moss but most will be OK so long as there is no fungal nasty in there with them.

Somerset Phil

[Phil Hocking]

Another thought - pond water is sometimes sterilized by passing it through a transparent pipe subjected to a powerful ultraviolet light. Has anyone tried shining such a light on the soil surface?

Somerset Phil

[Phil_SK]

Even if this worked, pathogens from below the surface would surely work their way up in time.