Putting in my first organic vegetable garden next year, so forgive me if my
questions are a little naive. I'm trying to get everything tilled up now
and let it rest all winter. I've skimmed several books, one of which
mentioned "Double Digging" tilling. Here's a parphrasing of the process:
Dig a 1 foot trench down the long side of the garden. Keep the top soil in
the garden, but take the rest and throw it in a wheel barrow. After
finishing the trench, go back and dig down another foot of subsoil and put
it in the wheel barrow. (Sounds like a big wheel barrow). Mix the subsoil
with peat moss and compost before putting it back in the garden. Make the
mixture one third peat moss plus two thirds compost, plus one part subsoil.
Rake the top soil back into the trench, then add the new subsoil mix on top.
Dig another 1 foot trench and repeat untill garden is all tilled. Tamp down
when finished. Expect bed to be about three inches higher when finished.
Wait at least a month before planting.
Bascially, I wanted to ask the group if this seems like a sound method. I'm
in western PA and my soil tends to be on the clay side. I don't think I'll
go as deep as two feet, but because the garden area is new, I do plan to go
deeper than one would for standard tilling. In particular, does the mix
sound right? BTW, when they say peat moss, am I to assume they mean peat
hummus? And for compost, I expect to use mostly manure (bags). Is it
reasonable to assume the bed will only be rasied 3 inches?
There is still some grass on the plot I plan to use, and with winter coming
soon, I doubt I'll have time to cover it and kill it with black plastic. If
I just till the grass under, and then cover it and let it sit all winter, I
should be fine, right?
Oh, this might be a dumb question, but... If putting black plastic over
grass for a couple weeks kills the grass, why doesn't the grass die when
covered by snow all winter?
Double digging is double digging, 'tilling' done with a tiller, is a
mechanised version of hand digging (a bit like ploughing) I suspect the
book may have UK terms in some of its origin. Peat moss is not incorrect
though I guess Moss Peat; that is, peat made from moss, is what is
referred to. It is humus as you describe.
The moss is just used to add humus.. You could equally add mature leaf
mould (2 - 3 year) or similar.
Compost can be of your choice. Matured animal manure is fine as is home
made compost (from kitchen waste etc). AS long as its partly rotted eg
Digging is often measured in the length of a spades blade or 'spits' so
you can substitute 'spit' for 'foot' in the measurements. Though I guess
it depends on how big a spade you use!-)
You can adapt double digging like this.
Remove your first spit depth trench of soil and move it to the 'end' of
the are you intend to dig. Fork manure/humus/compost into bottom of
second spit spit of soil.
Fill first trench with soil from 2nd and continue this method across the
area to be dug.
When you reach end of the area you will have your soil from your
initial trench to fill in.
Lift the turf and stack upside down, covered under plastic. Next year
you will have a ready made loam pile for potting etc.
Snow lets through enough air and light and is naturally cold so
minimises growth. Black plastic only cuts out light and air.
I have a little "home made" compost, but the rest will be store bought
bagged manure, which is certainly rotted.
But the rotted manure IS the compost, right? And is the two thirds compost
+ one third (peat moss) humus about right in your opinion?
Hmm... What you suggest sounds like a good tip for making good loam, but
is that necessary? As I said, I have grass on the area designated for the
garden but it's spotty and useless as sod. In the process of the Double
Dig, I was planning to just work the grass into the mix. After I Double
Dig, I was planning to cover with plastic and leave it for all of winter.
Is there anything wrong with doing it this way? It would save some work,
which is important with old man winter coming around the corner.
Ah, I figured it was something like that. Thanks.
Thanks for your time and your advice Jim.
Oh, is there any kind of a generic calculation one can use for figuring how
much hummus and compost I'll need? I really don't know how much to get.
BTW, my book says to expect the soil to be built up about 3 inches, but it
seems like adding all that hummus and compost will raise it much more than
than. What do you think?
Well, you have an area for your garden, say it's 10' x 20'.
Multiply 10'x20'x(3inch)x(1foot/12 inch)
and you get 50 cubicfeet. (ft^3)
Most garden stuff is sold in either cubic feet or cubic yards.
1 yard^3 = 3ftx3ftx3ft' ft^3
You might be able to get away with a little less since tilling the
soil will fluff it a little.... but the more organic material the
Verso l'esterno! Verso l'esterno! Deamons di ignoranza.
A good idea if you have the time and energy.
The idea is to dig 2 "Spits" in depth a "Spit" is the depth of the blade of
your spade, don't worry about it being less than 1 foot.
Yes you take out a trench and put the soil aside, but to make life easier,
if your plot is 20 foot wide then treat it as 2 10 foot plots so put the
soil next to where you take it from. dig up to the end of the plot then back
down the other side. No heavy trucking of soil from one end to the other.
The idea of double digging is to break and pan that may have formed, to
improve the texture of the soil and to give the plant roots a greater depth
of usable soil.
As you dig, skim off any weeds from the top layer with about 2 Inches of
soil, and work this together with any form of humus, Peat, compost, manure,
other annual weeds etc and dig these into the lower spit,
then the top spit is dug to cover the lower dug spit, and so on till you
finish, then just replace the soil that came from the initial trench into
the trench you finish with.
If you are a real glutton for punishment you could even treble dig.
Double digging and treble digging were quite common during Victorian times
when labour was plentiful as was manure. In those days they also used a
system of making "Hot beds by taking out a trench about 4ft wide and 12 to
18 inches deep then building a bed 2ft of so high of fresh stable manure,
and covering it with the soil removed from the trench, this manure would
heat to over 160 F then as it started cooling Glass frames were placed over
the bed and veg plants were planted, the heat from the manure giving the
plants bottom heat and frost protection, so that you could grow things like
lettuce, cucumbers, melons and a wide range of crops out of season.
This form of gardening could use up to 200 tons of manure a year.
Now back to topic. Tilling (Rotavating) is useful for rapid cultivation but
has the drawback of chopping up any perennial weed roots and thus spreading
them , and the blades will cause the soil at the base to form a "Pan" where
the blades rub along the bottom, especially if your ground is clay and is
wet, or even just damp when you work it, so digging is advisable every so
On farms where the ground is "Rotavated" the use things like sub soilers to
break this pan and to help drainage.
Thanks for the advice. I'll experiment with a few methods and see what
works best. I liked the history lesson, but it's just me, so labour ain't
so "plentiful". I'm staying away from the treble dig. ;) But, I will
avoid the tiller this time around.
Personally I wouldn't use peat moss, over here certainly it is a cause
for environmental concern. Its also pricy! Compost on its own should do
just fine. Yes rotted manure is a source of 'compost' but its not quite
the same as 'compost' if you see what I mean!
Poss but the grass may regrow.. If you turn it over as sods though its
almost the same as stacking!-)
Depending on how cold you're winters get, you might consider a cover
crop instead. Grazing rye or Field beans ( an agricultural cultivar of
broad bean) are ideal and very hardy.
Similar thing as covering with placcy but looks nicer!-)
Dunno depends on how bad your soil is.. If you're doing a prime prep
and want to do it properly I'd reckon half to 1 barrow per m2. You'll be
surprised how quickly the soil resettles once the worms and soil
organisms start to further break down compost.. It may be raised at
first, but will soon go down. I know a guy who double digs manure into
his plot 'every year'!! Not required IMO, but he does grow good veg!-)
Mind you he also uses chem fertilisers.
Well broken down store bought manure is probably the best I can do at this
Okay, I'll do the best I can with it. Much of it is already overturned and
Agreed, but I'm sticking with plastic for now. Cheaper and easier to work
with. Maybe once I get better at gardening, I'll make the switch.
That's a good guideline, and no, I don't plan to double dig every year.
Yeah, that just doesn't make much sense to me. A big reason for gardening
is to get things organically. Especially here in the states where our
argricultural laws allow for far too many inorganic substances in the food.
We're still ingesting stuff you folks outlawed years ago.
Peat bogs (from which much bagged garden peat is taken) are often SSSI's
(Sites of special scientific interest) as they contain rare species of
flora and fauna. They take a VERY long time to replace and cutting peat
destroys the living top layer.
I dunno you'd be surprised how many loopholes there are in the laws even
Yes do, but be sure its at the bottom so it won't regrow; see below
After I Double
I'm just in the middle of doubledigging a new bed in what was lawn,
Skim off three rows of turf/sod/grass by cutting it into tiles an inch
or two deep with the spade, then sliding spade underneath. Put them
aside on a plastic sheet, out of the way of your working area. Dig out
the uncovered soil two spits deep and put it aside, not on top of the
turves you just lifted. Now skim off your next three strips of turves,
and as you work put each one upside down in the bottom of the hole you
dug. Spread on the turves whatever soil improver you're using; don't
worry much about proportions but try to spread each material evenly.I'm
using seaweed, rotted horse manure, and a LOT of coarse grit because our
rainfall is high and this is to become a freedraining bed for sunlovers.
Dig 2 spits of soil you exposed when you skimmed off the turves, and
roughly pile it into the hole on top of the upsidedown turves (it will
look mountainously high, but will settle later).Keep repeating this
When you come to the end, you will end up with a hole where you just
finished digging. Fill it with the first turves and first soil which you
It's hard work, so to protect your back and joints stretch and warm up
beforehand and take it slowly, with plenty of rests. Make an effort to
change which foot you're digging with, on each row,to even out the
Covering the finished bed with (black)plastic will stop weeds
germinating during late autumn; but I prefer to let them germinate so I
can easily hoe them off before planting the bed. Also, you really want
the winter rain and frost to break up all the lumpy soil and settle the
Isle of Arran, Scotland.
Having used a tiller for some years, I'd advise only using it to
prepare the bed. It really beats using a shovel in heavy soil. Make the
trench, amend the soil, put the soil back.
I stopped using the tiller on my prepared beds, let the soil create a
structure again. If I was to add further compost, then I'd consider
using the tiller again... But it's a bit hard to lift the 6HP Troybilt
high enough to get into my beds.
Reply to me at louis little punctuation mark ohland with the same ISP
I really considered this, but I don't have a truck an my schedule is bad for
setting up a delivery time. I agree that a tiller is probably the way to
go, but I think I'll actually enjoy doing it myself. Oh, and I ended up
using cheap brick to boarder the garden because all the wood I found was
treated with chemicals I wouldn't want to go into my vegetables. It's been
a bit of a chore getting the brick to look right on the slight slope the
garden will go on and I hate to mess it all up with a tiller I'm not
Unless you are running the tiller about an inch deep to destroy weeds
between the rows it's a real good idea not to till unless you are
tilling organic material into the soil.
Once you dig the trench with the tiller and remove the first foot of
soil till all your organic material into the clayey subsoil and return
the first foot to where it was. A good way to use shredded leaves and
There is a school of thought (and a very viable one) that suggests doing
away with double digging *or* tilling and simply amending, amending,
amending. The 'don't till' school says that tilling destroys or seriously
harms existing beneficial bacteria and in general, the tilth and aeration of
the soil. Also, tilling will disturb the tens of thousands of weed seeds
laying dormant and waiting to be brought closer to the surface to germinate.
I have to admit, I was skeptical, but after laying down an enormous amout of
organic material along two sides of my property (approximately 80 cubic
yards), I'm a firm believer. About a year later the organic material had
filtered down at least 10 inches, with abundant earthworms moving between
the organic and hardpan clay layers as well. I used a combination of wood
chips, shredded leaves, bark, whatever it was that the city in which I live
dumped in my driveway.
If the project were mine, I'd lay down clear or black plastic sheeting for a
few weeks/months, which would cook not only any existing weeds but also
their seeds... then amend the heck out of it and perhaps lay downa green
cover such as winter rye, mustard, clover, etc. In the spring you can turn
under all that great green plant material and plant in your garden, amending
regularly with good stuff such as pine needles, manure, inert straw, grass
clippings, shredded leaves, etc.
Just my $0.02,
PS the grass doesn't die beneath snow cover because there is still a
suprising about of oxygen amongst the snowpack, as well as light.
Thanks David. I'll have to think on that. The way things are going, I
might not have an opportunity to do much digging before the ground get's
hard and miserable to work. Whether I till or not, I'll be sure to have
black plastic on all winter.
"........Whether I till or not, I'll be sure to have black plastic on all
The plastic will stop the rain going into the part covered .....but it has
to go somewhere so all round the sheeting you are going to double or treble
the amount of water.
If you cover a few weeks before you want to dig, or better, cover AFTER
digging to warm the ground before planting would be a lot better.
It doesn't matter if you do have weed growth of a few inches if you are
going to dig it in, in fact it will be of more value than a little dead
growth, and covering wont kill off perennial weeds in less than a year.
Remember if you keep it covered then it wont dry out if the water has got
under the sheet half as fast as uncovered ground.
It's getting cold fast, so no time to put plastic on the bed first before
digging. I don't plan to plant until spring at the earliest, but I was
hoping to kill the weeds and grass over the winter.
It's my understanding that with Double Digging, the ground should rest at
least a month, that's why I'm doing it over winter instead of wasting time
next growing season. I'm sure you're right about the perenenial weeds, but
at least I'll get most of it, including the grass.
I hadn't thought of that. Maybe I'll double dig, aply the plastic and just
leave it be for a few weeks. I my area we don't usually have heavy now on
the ground all winter, especially at the start of the season. I'll try to
remove the plastic once the grass is sure to be dead
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