[Greek Gardener]

We have a wood burner for which we have a supply of trees, especially olive.  I'd like to know if I can add the sawdust and ash to the compost bin (and in what percentage to other waste) or can I  just dig it straight into the veg patch.

[Trillium]

You can add some ash directly to the garden but the rule of thumb is about 1 cup per 3 square feet. It's potent stuff and you shouldn't overdo it. Rest can be added in thin layers in composting, but not above 1/4" per layer or you risk suffocating the compost. Same with sawdust. If it's fresh, you're better off sprinkling it lightly through compost. Its not really wise to use fresh sawdust as mulch or anything as it can rob soil nutrients so it can breakdown easier. Best scenario, make a special sawdust compost bin and you can simply add some men's urine to help break it down.

[solway cropper]

I don't know if you have access to grass mowings but if you do these can be mixed with the sawdust to make a reasonable compost. I normally leave it for about a year to rot down.

I agree with Trillium about the wood ash - use it sparingly. It is also alkaline so it might be worthwhile to check the pH of your soil before adding any.

[JohnB47]

You can add some ash directly to the garden but the rule of thumb is about 1 cup per 3 square feet. It's potent stuff and you shouldn't overdo it. Rest can be added in thin layers in composting, but not above 1/4" per layer or you risk suffocating the compost. Same with sawdust. If it's fresh, you're better off sprinkling it lightly through compost. Its not really wise to use fresh sawdust as mulch or anything as it can rob soil nutrients so it can breakdown easier. Best scenario, make a special sawdust compost bin and you can simply add some men's urine to help break it down.

Hi Trillium - in what way is wood ash potent? I have a woodburner too and I've never used the ash on either my garden or allotment - mainly because I burn a fair amount of scrap wood that has it's fair share of nails, paint and I suspect other treatments. (Obviously olive ash would be nice and 'pure').

I seem to remember hearing someone (Bunny Guinness?) on Gardeners Question Time saying that using wood ash as a source of potash was a waste of time - far too little to have any real effect.

So what's potent about it?

Thanks.

P.S. I'm green with envy about a fellow woodburner owner having a good source of olive.

[Trillium]

http://ezinearticles.com/?How-to-Make-Caustic-Lye-From-Wood-Ash&id=2118612

You're probably wondering why I've added an article about making lye for soap. But this is why you can't add too much. Lye is caustic. And just a little bit of water and a few handfuls of woodash can make a very caustic brew of sodium hydroxide. Hence the need to be sparing with it so that there's only just enough to help unlock soil nutrients.

http://en.wikipedia.org/wiki/Lye

To add masses of it to your soil will cause a very similar reaction - ash and (rain)water. Veg plants are shallow rooted compared to trees and will feel the effects immediately on planting. A few years back, a neighbour of mine decided he'd give his veg beds a real kick and dumped a winter's worth of wood ash in his garden. Everything he planted that year died. Same with the following year. In the 3rd year the hydroxide had neutralized and he was able to grow veg again.

[bigben]

my allotment neighbour has two plots one of which is almost all onions. He spreads his wood ash from his wood burner, over a fairly large area and it does help him produce really good onions. He says it is the potash they like. For the past few years he has been growing 2000-2500 onions which I think he sells. I am amazed he has not suffered from white rot as he never rotates.

[flitwickone]

my allotment neighbour has two plots one of which is almost all onions. He spreads his wood ash from his wood burner, over a fairly large area and it does help him produce really good onions. He says it is the potash they like. For the past few years he has been growing 2000-2500 onions which I think he sells. I am amazed he has not suffered from white rot as he never rotates.

wow im envious

[flowerpower]

I've been told that a few handfuls around the base of roses is OK, and a sprinkling on the compost heap is OK too.... but thats about it.
I grow a lot of onions as they like the soil around here, but without any wood ash.
I empty out 2 panfuls a week from my stove, and it seems such a shame not to use it somewhere.

If anyone has any more ideas as to what to do with it, I'm all ears!

[Lindeggs]

At our last house we had a woodburner stove and I put the ash around the base of some trees on the boundary.  The landlord was thinking of cutting the trees down as they had never thrived there and were very weak and spindly.

Well after I started applying wood ash the trees thrived!  They had new leafy growth all over them very quickly.

Now I have to admit that the ground around the bottom of these trees was quite heavy, compacted clay.  When I added the ash I poked a garden fork in around the base of the trees a few times.  So it may have been the aeration of the soil that did some good, but I do believe the ash made a big difference too.

By the way, the trees were kohukohu (pittosporum).   Something like this: http://en.wikipedia.org/wiki/Pittosporum_tenuifolium

I don't know what other trees would benefit from ash, but the fact that their roots are so much deeper than vegetables probably means that it wouldn't harm them.