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- How to make your own potting compost.
It's late January and we're heading up
to a really busy season of raising plants,
propagation, and for that, it'll really improve
your growth in the garden all year
if you can get a good potting compost
that you can use to fill trays and raise
lovely strong plants right the way through the season,
in fact, and in an undercover space,
that enables a high success rate,
especially if you get a good compost.
So we've been doing some trials here,
even though it's January, just to see,
to trial a few composts and to be able to show you.
So for example, this is multi-sown radish
in one of the trays I designed, that's a CD60,
which has quite small tapering cells.
And that means you don't need much compost,
but if you don't have much compost,
it needs to be a good one.
And, well, I think we've got some good ones here,
but even so, there's an interesting difference
between the two.
So one end is a purchased compost, which, still good.
There's nothing wrong with it, but that's the homemade,
and you know, I'm really quite surprised actually,
at how good the homemade compost is, but it's quite special.
I'll explain that in a minute.
We're going to have a look outside
at all the different materials,
ingredients you could put in there.
And if you can get a good compost in a tray like this,
so these are multi-sown with
average three or four radish per cell.
There's 60 cells there, so there's 200 radishes in there.
You know, it's like, wow.
In a small space, you can raise a lot of plants,
especially when the compost is good and reliable.
Here, by contrast, we have two different composts.
And how would you feel if that was the one that you'd sown?
This one is the one I've been buying,
Pete's Peat-Free compost.
It's really good, and these broad beans were sown
about a month ago and they've been in here without heat
but it's been quite mild.
And this one is one that's actually
not sold as a potting compost.
So you could say in a way, it's not a fair comparison,
but nonetheless, for me,
there's something wrong with this one.
It's made from digestate,
which is generally a material I would avoid
because it's a little bit unreliable, I've found.
This is just what I've found,
and some of you might be doing all right with it,
but I've not yet had a success
with anything made from digestate.
Read the small print.
They don't always say clearly when you buy a compost.
Sometimes, this one's actually called organic compost.
Sounds really good.
So we'll look at this more in a later video
that we're going to put up about filling trays next week.
So let's have a look at some possible ingredients.
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There are some beautiful materials here
for making a potting compost, and to get them to this state,
we've done a bit of sieving, so there are sieving options
like how small do you want it?
This is 12 millimetre,
which does still have some larger pieces
of whatever was in the compost,
in this case bits of wood and twiggy stuff.
And that goes through a metal sieve,
which I found last year online.
It's pretty clever.
So we did this back in the 80s actually.
We had a metal bed frame at 45 degrees
and you throw stuff at it and the fine stuff falls through
and the larger stuff stays at the front
and trickles down to a pile.
And you've got the nice, this stuff.
In this case that's 12 millimetre sieve,
so you can see, it's pretty nice actually.
That's homemade compost, as it happens.
However it would not be ideal
for small module cells, for example.
Bit too much of this woody stuff,
which is not going to hamper growth.
Even though it's wood, there's not too much of it,
but it's not got a lot of nutrients in it.
We need two main things.
We need enough nutrients,
because we're using quite small volumes
or quantities of material, compost, and we need drainage.
So the drainage actually would be helped by that wood
And you could in theory make a potting compost
out of woody material.
It'll drain brilliantly, but it won't grow much plant.
So we need a bit of both, in small pieces
And we've been using this to sieve, actually.
This, funnily enough, it's slightly ironic.
That's from a wormery, a plastic wormery,
and the idea is the worm compost falls through
and also the worms can come up through this
if you stack these up.
That's four millimetres,
which is around a sixth of an inch.
and that lets through by shaking,
so it's a bit hard work to get lots,
but it's very possible, actually.
It's very possible to get a decent amount.
In fact, Adam was doing it last week
when the compost was slightly frozen,
so
that worked really well.
It was not soggy,
because if it's too wet and soggy,
a sieve like this won't work.
So thinking ahead, if you've got some compost
that you think you might want to sieve in a week or two,
put it somewhere dry, even in a shed on the ground,
spread it out and and let it dry a bit
before you try to sieve it.
So this is just to emphasise,
this is the tray I was showing you just now
with the radish, and it's not holding together very well.
This is a whole nother thing that we'll look at next week.
But here are some very nicely rooted radish,
but you can see that's four plants of a decent size
growing in not much compost there.
That's the point of what we're looking at here
is how to achieve that.
Those radish are ready to go in the ground, by the way.
They're quite big.
So different composts that we've sieved,
and what they look like.
This is homemade and it's 18 months old.
This is as nice a homemade compost as I've ever made,
and that will make, that'll be good for potting
I'm sure of that.
We did some trials last year comparing different composts
more in isolation just to see how they did,
and actually this one started a bit slowly,
finished very strongly.
And I'm pretty sure the slow start
was from drainage issues, when seedlings still have
very small roots and as the root system developed
and got stronger, it mattered less.
But we are mostly looking here
at something for very small roots,
so that's where the drainage is so important
and where the wood chip, this believe it or not,
is wood chip sieved to four millimetres,
actually about three years old.
It's some I got delivered here two years ago,
when they claimed it,
They claimed it was two years old already.
You never quite know.
Anyway it doesn't matter, it's more what it looks like.
But if you can get it looking like that,
well that's quids in, and I'm finding this works really well
as an adjuvant to improve drainage,
holds air in the compost as well as providing some goodness.
So these are all possibles, and here's another one.
An amazing possible, this is worm compost.
It's the first time I've specifically made worm compost.
We've had worms, so that's Eisenia fetida worms,
not the same as the big fat pink earthworms.
These are the small red wrigglers, wiggly wigglers
or tiger worms, red brandling worms, very similar.
And they're the ones that just appear
when you have a compost heap, if it's not too hot.
So we don't get them in our main compost heaps
until towards the end, when the heat's gone.
And that's great.
Then they come along and you kind of,
they'll turn it into worm compost
if you left them long enough.
Or what we do over there is have a dedicated area
for worm composting where we don't add
too much material at any one time, so it never gets too hot.
They keep eating and through the year,
you're adding material on top.
The worms are rising with that adding food material.
And just three weeks ago,
we actually scraped off that top there,
finally, after 10 months of doing that,
and put them onto one side, the other side of the bay
and that's now this year's wormery.
And lifting up the black plastic,
you see, usually you see the worms there.
Sometimes slow worms as well.
And at the moment though, because it's quite cold
and we're having a frost every night,
the worms are deeper down and you don't always see them
but they're still there.
So this is average,
probably six to eight months old worm cast, basically.
That's beautiful, that's rich,
but what we found last year, and I noticed how
in different mixes with different proportions of worm compost,
that around 20% looked to grow the best plants
rather than say, a hundred percent.
I did 100%. That wasn't so good.
I think again, maybe a drainage issue,
which is why I'm actually quite impressed
by these radish here, how well they're growing in 50%.
of this worm compost, and 50% wood chip.
That is working.
That's a mix that is working for me at the moment.
It's not like I can give you the perfect recipe
that's going to work every time
'cause your worm compost will be different to mine.
Your wood chip will be different to mine.
So you've got to play around a bit.
It's a chance to be creative.
That's why, keep in mind those two basic things.
You need enough nutrients, you need decent drainage.
And for drainage, that's a reason not to use soil.
Believe it or not, that's Homeacres soil.
It's looking as nice as it's ever looked.
That's because we've had some frost,
and so this is actually what's called a frost tilth.
Farmers love it, if they've ploughed their fields.
People who dig their ground love it.
You've got lumps and then the frost breaks 'em up.
You just touch it with a rake
and it all goes whoosh, beautiful.
That though, in my view, that's not a stable tilth.
If it then rained and you walk on it,
it'll all squash down again, and that's the difference
to no-dig where you've got the compost on top.
But soil is a possible addition,
I would say in small quantities.
Again, we noticed last year with the trials,
we added maybe 10% soil, something of that order.
If it's really good soil like this, could be up to 20%.
It's very interesting also, the difference in weight.
There's a lot of material in there.
So we were just checking on the scales,
and this one roughly, in a 10 litre pot,
that weighs about 6.9 kilogrammes.
Meaning that's 70% weight.
If that was water, if that was full of water,
that would weigh 10 kilos.
Water is so dense and heavy.
So we're getting close to that,
and the wood chip compost by comparison is much lighter
that was 3.8, 3.9 kilos.
And the lightest one of all was this,
which is clearly not soil or compost.
That's vermiculite, which is a kind of expanded rock.
And it's, as far as I'm aware, a natural product.
It's not a plastic or anything like that.
Another version would be perlite, similar.
My mother, bless her, in the old days,
she used to add some balls of polystyrene,
which, yeah, wouldn't be so keen on that now,
but the idea is the same,
which is to hold some air in the mix.
And I would mainly think of using this one
where I'm using a bit of soil to balance those two things.
Whereas the very successful radish there
doesn't have any of this.
this is not bligatory, but it's a possible option.
And likewise, another option could be wood ash.
That's from my wood burning stove.
That's quite rich in potash.
I tend not to worry too much about nutrients
because these, I'm finding, all have it more or less good,
But if you wanted a bit of extra potash,
this might be more actually for if you've growing
tomatoes in containers, that kind of thing.
And then we've got rock dust. Wow, this is really heavy.
Partly 'cause it's wet.
That's basalt rock, volcanic rock,
and that's claimed to have
lots of trace elements and minerals.
I'm still a little bit "jury's out" on this one.
I've used it with not huge success,
but I will sometimes put it in,
just as kind of a covering all bases kind of idea.
What I would prefer to have actually,
from that point of view,
for trace elements and minerals is seaweed.
I haven't got any here.
You can buy seaweed in powder,
and if you can get it as a green powder,
there's a company in Ireland called Better Plants, I think,
who sell seaweed powder, make it in a very low heat way,
and I had good results from that last year.
Used it all up now.
And there are other options I haven't mentioned.
In fact, these three kale plants give you an idea.
These, believe it or not, have been growing
in these pots, two-liter pots,
for six months, without any feeding or anything.
That's the result.
I would say they're all good composts in their own way.
That one actually is cow manure.
So well-rotted cow manure.
it was probably about 18 months old
when it went into the pot, it's not sieved.
that's the homemade compost,
but a slightly more woody version
than what I just showed you,
and that was sieved to 12 mil, not four mil.
And this very strong plant is from mushroom compost.
You know, there's another option for you.
If you can get some mushroom compost,
I would age it a bit.
So usually when it it's sold to you,
it's a bit fresh and if you left it
two or three months, results would improve.
and you probably don't need to sieve it
'cause they've done all that.
Just break up the lumps, and there's options for you.
I do a propagation course online.
You could find out more there about how to raise plants.
And also in my children's book, which is recently come out,
there's a bit about propagation, raising plants.
I have really fun thing to do with children.
And we'll put links to all of that on my website.
We've got a course here at the end of March in propagation,
just an afternoon course.
And I'll see you in the sequel to this video,
which is about actually how to use these composts
and what to put them in.
There's one thing more I've remembered, actually.
I've not actually made a compost,
so I'm just going to do this now.
I'm going to show you a way
we can mix it very nicely.
Maybe not all of these.
This is 10-liter pot.
I've put about eight litres of the homemade compost.
Wood chip, I'll put about the same.
And then the mushroom compost,
I will put a smaller proportion.
Sorry, the worm compost.
Maybe about half the pot there.
It's amazing, half frozen
I'm feeling there's granules of ice in that.
It's been very cold here overnight.
Soil. Whoa, I need two hands.
Just a little bit.
I notice actually there was
a bit of a bindweed root went in there.
This is something to watch out for with soil,
perennial weed roots and also seeds.
Abundant even weed seeds.
A little bit of vermiculite
just to kind of balance the soil.
Two handfuls, that'll do.
A bit of rock dust just to see.
And wood ash, I don't think I'll bother.
So a really good way to mix is
pouring, 'cause when you pour,
you get a kind of gradient, a slope,
and what's in the bottom of the bucket
comes out quite increasingly halfway through.
So each end goes to another end eventually,
and what's in the middle goes to both ends as well.
I'm just doing this four times, you could do it more.
In fact, doing it another time wouldn't hurt.
I'm noticing now, vermiculite's a good way to tell.
the vermiculite is appearing throughout
and we're getting a nice steady mix.
So here we are, two decent buckets
and we now have a very nice compost for propagating.
You could use this for sowing actually,
because it feels nice and light,
as well as for raising plants.
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