If you have just finished building a raised bed, maybe even using my guide, your next thought will be, what soil do I put in my raised bed?
Let me help you out and offer a few money-saving tips!
When it comes to filling a new raised bed, you have lots of options. You could go out and buy lots of compost bags and fill the raised bed with compost.
This would create an excellent growing environment for your plants, but it would be costly and pretty wasteful at the same time. It would also rot down pretty quickly, leading to shrinkage in the amount of compost in the bed.
The soil right at the bottom of your raised bed won't really be used, so you don't need to fill it with expensive compost!
Saving money on filling a raised bed
The bottom of a raised bed is not particularly important, at least not at the beginning of a raised bed's life.
That means that filling the whole thing with compost is just throwing money away, and you miss out on some nice benefits that come with putting other stuff in.
So what is this other stuff?
I like to start the bottom of raised beds with really bulky waste. Stuff like sticks and logs, really big bulky material that will take up a lot of space, reducing the amount of compost you need to put in your bed.
All of this will rot down over the years and provide good nutrition to your soil for years to come. It also helps introduce helpful fungi and soil bacteria - all crucial for a healthy growing environment.
On top of the logs, I like to add grass cuttings and weeds, the kind of stuff you would add to the compost heap.
Just be careful with what you are introducing here, don't go adding horsetail roots for example or you might find yourself fighting them off for years to come.
The same could be said of dandelion roots but on a smaller scale.
Adding Garden Soil
This is where some added benefits can come in. I like to add plenty of ordinary soil from the garden/allotment into my raised beds.
You can see the big square of lawn turned upside down in the middle of the bed above for example.
The benefits you get from this are obviously filling your raised bed up for free, but more importantly, it is all the natural life you are adding to your raised bed.
There will undoubtedly be many worms in that soil I just dug up, now living in my raised bed. These will work away to improve the soil for me from now on.
Beyond just the creatures you can see, there will also be lots of smaller creatures like nematodes that feed on slugs, along with all the good bacteria that make up healthy soil.
If you just add pure compost, you are missing out on all this, and if the bottom of your raised bed is sealed, then how are things like worms ever going to find their way in?
Add onto this the fact that some store-bought composts are actually sterilised, and you then have a strange soil in your raised beds, devoid of the usual life that helps plants thrive.
Compost top layer
Once the raised bed is getting near the top I add plenty of compost to give the plants that will be growing in the bed plenty of nutrition.
You can use compost from your heap if you are lucky enough, or if not, store-bought compost will do just fine. Use regular multi-purpose compost, or peat free if you want to be more environmentally friendly.
So there we have it, a filled raised bed at a fraction of the cost of filling it entirely with compost, and the bed is healthier. A real win-win in my eyes.
Shrinkage
If you fill your bed in the way I described above, it will shrink over the years. This is to be expected and is just a sign the stick and logs near the bottom are decomposing and taking up less space.
Just give the bed a top-up with some compost every now and again to keep on top of the shrinkage.
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