Biggest mistake this year

pclark42

I started a compost heap last year, I made it from used pallets as others do, it filled up with all the garden and kitchen waste, and by November I decided to add a 2nd just so that I could concentrate on the first one, I followed advice from youtube vids, and by the end of January this year I had myself some fairly useable compost (a bit woody but useable) I passed some through a riddle and used it in a 50/50 mix with some John Innes to sow some vegetable seeds and a few Sarah Raven flowers, within 10 days most plugs had something growing (all were labelled up) however I started to wonder at just what I had grown, it turns out most were weeds obviously from my compost, I had to sort through them all, and I couldn't save many of the flowers and had to start again, and so until I find out what I did wrong I will stop the compost production.

pansyface

No, you did nothing wrong. The compost just didn’t get hot enough to kill off the weed seeds.

I gave up long ago trying to make compost hot. I’ve tried everything and it just doesn't do it for me.

But I still make lots of compost and use it in pots where I’m sowing seeds. I just add an inch or so of sterilised commercial compost on the top. That suppresses many of the weed seeds.

Any that do pop through are recognisable from the “real” seeds once the first set of true leaves appear.

Fire

Just don't put weeds in it. We learn as we go, don't give up. You can probably use your current compost as a mulch if you put other material on top to block light - something like manure, bark, or woodchip. It's trickier if you have put something like bindweed in it the mix. I did that when I first started. My housemates were not best pleased.

Some leading lights in the compost/no dig world get a evangelical about the composting world. I have seen them stating that you can put anything in, weeds, cooked food, everything, and it will be fine, with no caveats. This is daft. It pays to be careful, esp at the beginning. It takes a certain kind of size and mix to get compost beds hot enough to kill pathogens and seeds. Most people don't get anywhere near that.

Palustris

The only way to get a heap hot enough to kill weed seeds (and other nasties) is to turn iit over every day and keep it well watered. So who has the time and energy to do that?. the commercial peat free compost makers do that.

When we had the room we had what we called the non-compost heap. We put into it all the seeding weeds, dock roots, dandelion roots, in other words all the things which should not go into a cold compost heap. The non-compost heap was covered with a black plastic sheet and left for about 5 years. It was usable then.

Hostafan1

The trouble stems from the word " compost ". 
Garden "compost" is primarily a soil conditioner and not really consistent enough to use for seed sowing. 
Garden centre "compost" is a sterile growing medium. 

LG_

Your 'mistake' was not in making compost, but in using it for seeds. Pansy's method is the only way I'd do it, otherwise use bought sterile compost for seeds and homemade for myriad other uses. It sounds like you've been very successful in making compost and it would be a shame to stop.

Dovefromabove

As has been said, there’s 
Garden Compost and Potting Compost ... two different things ... I keep saying it ... I have bruises on my forehead ... 

Hostafan1

Dovefromabove said:

As has been said, there’s 
Garden Compost and Potting Compost ... two different things ... I keep saying it ... I have bruises on my forehead ... 

Ditto

Palustris

If you read some of the old gardening books the growers then often used their own 'compost' for seed sowing (plus the soil from mole hills). I often wonder how they went on with weed seed germination. Trying to explain the difference between compost heap material and sterile seed sowing material is as Dove says one of those never ending head banging gardening advice problems. It comes up almost as often as identifying Thorn Apple or Shoo fly plants.

Hostafan1

Palustris said:

If you read some of the old gardening books the growers then often used their own 'compost' for seed sowing (plus the soil from mole hills). I often wonder how they went on with weed seed germination. Trying to explain the difference between compost heap material and sterile seed sowing material is as Dove says one of those never ending head banging gardening advice problems. It comes up almost as often as identifying Thorn Apple or Shoo fly plants.

and Carex pendula seedlings

pansyface

I can tell you how my dad did it.  Once.  Only once.

He put his garden compost into my mum’s best roasting tins, set the oven to gas mark 8, put the tins into the oven and left them there for a few minutes.

Mother returned from her weekly visit for tea at a friend’s house just in time to find the experiment in progress. What’s this smell??????

Roasting tins, compost and father were thrown out into the garden.😁