Cardboard as a filler for garden beds

Question

Hi there,

I have read some of the previous posts about using cardboard in compost (for high fibre and carbon etc), but I wanted to ask if there would be any problems with using it as a base filler for raised vegetable garden beds.

We have recently purchased some raised beds (corrugated iron variety) which we purposefully bought dimensions that are just under a metre high so to minimise bending for back problems.

We do not wish to fill the whole void with good soil or composting as it would be wasted when the roots will only go so deep, so we are trying to think what we can use to fill up the bottom foot or so before adding the good stuff.

Will cardboard boxes (whole and flat – ie not cut up into small pieces) be okay for this purpose?

Will they create any problems with the bed?

I know they will take longer to break down this way but this would be a positive as it would be for fill purposes only. But will this create any negatives by using them in this way at the bottom of the beds.

note: the raised beds are bottomless and we have cleared the grass underneath already for the shape that they are.

Your comments will be appreciated.

Answer 1

Yes, they should be fine with a cardboard base. You can also consider gravel. This is a common filler for the bottom of raised beds because it helps with drainage.