Leaf mould as seed compost

jo.ilott · June 2023

I saved leaf mould for 2 years and was excited to use it as seed compost but was disappointed with the result. It didn’t give a good germination rate compared with the shop brought seed compost & I found I needed to sterilise it in the oven as it had lots of other seeds growing in it. Has anyone had a good success with seed sowing in mature leaf mould?

StephenSouthwest · June 2023

I've had good results from mixing it half and half with Sylvagrow multipurpose. I found it was holding too much water on its own...

Fairygirl · June 2023

It would usually need sieved and used in conjunction with other things, depending on what you're sowing. Grit or Perlite would normally be added for drainage.

I normally only use it as a mulch.

bédé · June 2023

It depends on what tree the leaves came from, and how well decomposed the leafmold is.

I sterilise and then sieve. I then blend it with vermiculite or perlite/sand depending on the particular seeds.

jo.ilott · June 2023

I did sieve it & mixed it with grit or perlite. I agree with Stephen’s comment that it held too much water. I think I will use it as mulch in future as sterilising it is not practical for me. The leaves were a mixture of sycamore, oak & elm. They were very decomposed. Does it need to be 2 years old to be used as mulch?

Fairygirl · June 2023

There's really no need to sterilise leaf mould, even for seed sowing, so I'm not sure why that's come up @jo.ilott. It does need some help with drainage, which is why it depends on the type of plant you're trying to grow, and adding grit etc is usually needed as I sad earlier. Last year's compost is ideal for adding too - if you grow any annuals, especially in pots, that's great as an addition, because the nutrition is also depleted. Seed doesn't need much of that to germinate, especially if autumn sowing.

You can use it before it's totally broken down as a mulch - depending on where and how you use it. I don't use it round perennials if it's not fully broken down, as it can be too heavy and wet, but it's fine for anything woody - shrubs/trees/hedging etc. Your general soil conditions and climate will also dictate - in a very dry area, it could be helpful for emerging perennials, but the last thing mine usually need is extra moisture in spring/early summer

tigerburnie · June 2023

I haven't made leaf mould, but I have collected some to mix with loam to make potting compost, my Dad did it all the time in the 1950's, you could add extra boost with a bit of slow release fertiliser like fish, blood and bone too.

MikeOxgreen · June 2023

https://www.rhs.org.uk/soil-composts-mulches/leaf-mould

Lyn · June 2023

We used to have lots of very big trees here so my dad would collect and make gorgeous leaf mould, never needed sieving, he mixed it with sand for seed sowing.
always good results.

bédé · June 2023

jo.ilott said:

The leaves were a mixture of sycamore, oak & elm. They were very decomposed. Does it need to be 2 years old to be used as mulch?

Oak and elm are good. Sycamore has hard leaf=stalks that are slower to dcompose. And lots of seeds.

Decompostion is of the essence. Time AND temperaure. My normal 2 year quite cool composting cycle is perhaps not quite enough for the top-of-the-heap/winter 6months.

Fairygirl · June 2023

In the past, my leaf mould, from my own trees, were mainly maple, and some lime @Lyn . In this garden I have no suitable trees, but I got a load from the chap across from me which were maple, and from the girl round the corner which are all beech, as those houses are directly across from the boundary hedge of the little NT garden.
It all takes a good couple of years to break down here, so it would be difficult to use for seed sowing without a bit of sieving, even after that time. I also shredded some with the lawnmower, which can push the process on a bit too, and that was used round a couple of shrubs. I'd still prefer to use it mainly for mulching though, but it just depends on how much room you have for storing it, and how much time you have to wait for it to break down.

I used mine this spring for mulching, and for part filling big pots which I use for things like sweet peas. I needed to do some work in the corner where it was, so it needed shifted anyway, but it still wasn't as well broken down as it would ideally have been. A good 18 months since I collected it.

Leaf mould as seed compost

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