Veg Bed Height?

[chris]

Sorry if this is the wrong place - not sure what other forum it should be in?

I've just created some beds, as can be seen below.. but I'm not sure about the height of them?

I'm going to dig down in the ground, but not really sure if I should add another tier onto the beds?

What are the pros and cons of doing this? I've read that raised beds are better for drainage (unsure of the soil below the chippings - wanted to get the frames done first so I could see about walk ways, etc)... Most beds I've seen at friends places are pretty much this height (built them from 12'x6"x2" planks).



Side question: I've noticed seem green coming out of the boards, almost like green mould? The planks have been tanalised (after spending ages researching this, had a good chat with the local timer merchant owner who advised me all the hype about, and toxic chemicals have been banned from use in tanalising, and other domestic wood products - explained we have a baby, etc and said I NEED it to be safe - and he said it's definately safe - is often asked this, and has said that these boards will last up to 20yrs? Untreated wuld only last a year or two before rotting down? - is that true?) -- so that green stuff, could it be tanalising stuff coming out? These planks have been out side, pretty much all wet due to all the rain we've been having like - I'm going to give them a good blasting with a pressure washer to get it off, and then am planning on painting them with plant safe wood preservative (mainly for the look).

Thanks!

[Snadger]

The green is more likely to be algae a natural phenomenon. The height looks fine to me. If you go higher the soil will dry out quicker but will be warmer as the sides are heated by the sun!

[chris]

Thanks - is the algae nothing to be concerned with then?

It's washed off fine...

[Alison]

They look about the same height as mine which OH helped me with earlier this year. I double dug the soil below to ensure decent drainage and then just used the sides as a demarkation to the bed. Didn't add any extra topsoil etc but have a bit of space for adding organic material for next year.

[solway cropper]

How old is the tanalised timber? The original process used chrome and arsenic compounds which have been found to readily leach into the soil. Modern tanalising is much more environmentally friendly and the chemicals used do not get into the soil in the same way.

[chris]

Not exactly sure how old it is, but the timer merchant owner informed me that it was definately safe, after I mentioned about not using tanalised wood - as above he said that the "old" process was no longer in practice.

He said it's some clear water based (I think he mentioned) resin that's vacuum formed / injected into the wood (must admit, I got lost in all the stuff he was telling me about how it was done).

The timer doesn't look "old".. what sort of age did the new process come into play then?

Bit concerned now!

[Bigmallly]

If it eases your mind Chris line it with polythene or similar. I lined mine as I did not want to take any chances.

[Hazel at the Hill]

Nothing to worry about, Chrismarks - all new-sold wood will be safe from dodgy chemical leakage.

If you'd said you picked up the wood from a very old house reclaim/20 yr old railway sleepers etc etc it might be worth a passing concern, but not wood sold from the local timber yard.

The beds look lovely, too!

[chris]

ah ok thanks!

[vegmandan]

Get 'em as high as you can.

[Pumpkin Becki]

When we built ours, we fixed them in the corners with triple height posts. 1/3 in the ground, 1/3 supporting corner of bed, and 1/3 poking out of the top. This means that I can tie fleece on over the bed, or add another tier of timber if I want to. Sometimes I will for root veg, but our chalky clay hasn't deterred parsnips yet, I can usually grow them to about 30cm long (and longer). They are very determined!!