Another question from a newsletter reader. Paul has a simple question, about covering beds with cardboard and manure. But the answer isn’t quite as straightforward. So thanks for an interesting question.
A pile of old cardboard and soil.
Paul’s question:
Is putting cardboard down on my soil before manure, and leaving over winter a good idea?
Applying manure in the autumn is, with good reason, part of the traditional growing system. Assuming the manure is fairly well rotted, it gives the time needed for the soil to absorb the nutrients and convert them to plant-usable forms ready for the spring.
Normally, the manure would be spread over the surface and then forked into the top of the soil. Another traditional method is to add the manure into the trench when doing the winter digging. This mixing helps the soil microbes make contact with the manure particles and work their magic.
Traditional digging and ridging exposes soil to the freezing and thawing of winter weather, helping to create a fine tilth for the spring. If you’ve a light, sandy soil, that is probably not necessary, a bit of a waste of time and effort.
Even just spread on the soil surface, the manure is in contact with the soil and the soil microbes will work it. Maybe not as quickly as if it was mixed in, but things should work well.
Covering Soil with Cardboard
Covering the soil with cardboard over winter is relatively new. It stops weeds from growing and leaves the soil clean for spring planting. So long as the cardboard is plain and stripped of tape and shiny labels, it will break down quite well over the winter. Whilst it doesn’t contain any nutrients like NPK, it will provide some carbon which supports the soil life.
There is a problem with cardboard though, winter storms and winds. Not so bad when the card is soaked as it moulds itself to the soil, but freshly laid and dry it can blow away. Covering the cardboard with manure will hold the card in place against winter storms.
But…
So all sounds well, layering manure over card in the winter. But, there’s always a but, it does mean the manure is separated from the soil until the cardboard breaks down. This delay could mean the manure’s nutrients aren’t sufficiently merged into the soil and as bio-available in the spring.
Perhaps I’m over-thinking it, but I think the best way may be to put some soil in a barrow, apply the manure, then the cardboard and use the soil from the barrow to just keep the cardboard in place.
And finally…
Should we add the tea to the milk or the milk to the tea? 🙂
Now you are milking it John.
🙂
And most importantly, When should we add the tot of Whisky to the mix ??????
Definitely!
Milk to the tea, always!!
I have four x 1 metre square raised veg beds in my small garden. I mainly grow red onion sets, Frnch beans and lettuces. I find it difficult to keep to the three year crop rotation, as I do not grow potatoes or root vegetables as space too small, or brassicas because the pigeons eat more than we do. Can you please give me some ideas how I can use the three year crop rotation scheme? I have been using a two year rotation scheme for the last 4 years.
Thank you,
Roy.
Can I cover the beds with cardboard and then cover will weed suppressant over the winter? These particular 2 beds got quite overgrown with weeds this year so I thought it might help suppress regrowth.
Sound advice John. I use this method for raised beds and just but some bricks on top of the cardboard. Some varieties rot down quickly but those that don’t can be shredded and added to the compost heap in late spring.
For various reasons, we had to put some of our raised beds to bed earlier than usual this year — in early September. As the weather was so mild, and weeds were still growing, we put cardboard down before the manure to suppress the weeds until the temperatures dropped. It has worked really well on all of the beds apart from one — the bindweed bed!!! We had cleared the bindweed from this bed as much as we could before the cardboard/manure layers, and it looked good for a while. But what a shock recently when we looked underneath the cardboard to find hundreds of white ribbons of bindweed crisscrossing the entire bed. It’s like cooked spaghetti has been strewn over the whole space. It is easy enough to follow the runners back to the source and pull it out. But if you already have a bindweed problem, I would think twice about using the cardboard!
Though did you not find, Shirley that the bindweed roots were nearly all on the surface just under the cardboard and therefore easier to remove? If you hadn’t put the cardboard down the bindweed would have been just as prolific but under the surface of the soil and out of sight!
Hi Steve,
Yes, that’s true, at least it was easy to see, and easy to pull out. But it did mean scraping back the manure and mushy cardboard layer to expose it, and then re-covering everything again. But hopefully it’s knocked the bindweed back a bit. I was going to fill this bed next season with the variety of tagetes that supposedly suppresses bindweed as a type of green manure. Has anyone tried it before?
I am trying the manure and cardboard for the first time this year. I saw this suggested on a YouTube video channel called Evergreen Seniors. I put the manure down first then very wet cardboard on top so that it didn’t blow away. However I found it looked so ugly I needed a way to make it aesthetically pleasing even though it was working perfectly. So I added leaves on top, covered by coffee grounds sourced from a local coffee shop, to stop the leaves blowing away. This seems to be working. I won’t know the results till spring, but my plan is to plant through the cardboard. Isn’t gardening fun. Always new things to learn.
…… and Shirley, the bindweed will have used up a lot of its reserves producing this tangle of roots without any ‘pay-back’.
Hi Mike,
I really do hope it’s knocked the bindweed back a bit. As I mentioned above, I am going leave this bed fallow next year and just plant the variety of tagetes that suppresses bindweed (allegedly). An experiment of sorts. Fingers crossed!
Should we be concerned at all about using cardboard?. I have only used brown cardboard Amazon type packaging but concerned that it may contain chemicals that we might not want with our veg? Thanks
Matt brown cardboard is fine. I use any plain matt card or printed but not shiny.
I could be wrong, but I think shiny coloured card is best recycled, as I think the shiny layer is plastic.