We have constructed raised beds using concrete blocks and rendered them..now the learning begins.
My first question is what should I fill these with? The walls have been built on hardcore, so not a completely solid base.
I have read various articles and still can’t seem to come up with an answer. The beds are 60cm tall. So far I was thinking 15cm of gravel in the base topped up with 40cm of topsoil/compost mix (although still not sure in which ratios).
I have also seen it is advised adding grit to the topsoil/compost or adding a layer of sharp sand between the gravel and soil layer.
All a bit confusing for a first timer!
Im looking at some perineal flowers, small shrubs and a couple of small trees. Is 40cm of soil/compost adequate? Could I get away with a bit less (quotes are quite pricey for how much I need!)
Thank you so much in advance for any advice.
I’m sure I will be back to ask again when it comes to choosing what and where to plant.
What do you want help with, Nicolle? What to fill them with (follow on question, what are you growing?), what quantity you need to buy (follow on question, how wide and how deep?), where to buy the compost?
What do you want help with, Nicolle? What to fill them with (follow on question, what are you growing?), what quantity you need to buy (follow on question, how wide and how deep?), where to buy the compost?
Advice on everything and anything I think 😅 I have just commented my questions on the post.
First time starting a discussion, hopefully I’ve done it correctly.
The calculator provided by K67 suggests 3 bulk bags will be necessary for each bed.
I think I would be happy with a 15 cm base layer of gravel followed by the manure/sharp sand/top soil mix as recommended in the Which article. There are suppliers who provide special mixes for raised beds so googling that might prove an easier solution.
One word of warning, there have been many scare stories reported recently of manure contaminated by weed killers so practise diligence before you buy. Asking for recommendations of local suppliers on the Nextdoor.com website is always a good move.
I'm not sure what purpose the gravel serves as you have good drainage with the hardcore or put more hard-core in, you often get it advertised on free cycle. You can fill the bottom with garden compost, someone suggested asking the neighbours for the contents of their green bins but you don't want anything diseased, lawn turf or cardboard but they will rot down in time so beds will need topping up but you can do that by mulching every year. 40cm should be sufficient for most plants so is the gravel cheaper than the soil?
K67, yes mostly just to bulk it out. Although underneath that hardcore is very clay like soil that used to get quite boggy in the winter. We don’t seem to have this issue since laying the hardcore down though.
Bulk bags of topsoil/compost I have seen so far are around £80/90 and gravel only £40.
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Hoping you can help.
We have constructed raised beds using concrete blocks and rendered them..now the learning begins.
My first question is what should I fill these with? The walls have been built on hardcore, so not a completely solid base.
I have read various articles and still can’t seem to come up with an answer. The beds are 60cm tall. So far I was thinking 15cm of gravel in the base topped up with 40cm of topsoil/compost mix (although still not sure in which ratios).
All a bit confusing for a first timer!
Im looking at some perineal flowers, small shrubs and a couple of small trees. Is 40cm of soil/compost adequate? Could I get away with a bit less (quotes are quite pricey for how much I need!)
Nicolle
When we filled raised beds we found loam worked well. Used to have it delivered on back of tipper truck.
What is loam? How is this different to topsoil etc?
https://www.topsoilshop.co.uk/topsoil-calculator?gclid=Cj0KCQjw0oCDBhCPARIsAII3C_G5BoGwp7pDyHAek1EMdyO9cUbX0j2_ldlTFTIL1AuuApv39ogEj6QaAvVdEALw_wcB
I use this supplier https://www.cpa-horticulture.co.uk/
Soil will settle over time so if you don't fill to the top you might end up with too little depth.
Your beds might be deep and long but what's the internal width as trees don't do that well if too restricted.
Yes it costs but if you don't do it properly all your hard work will be wasted as plants are not going to thrive and you will never be happy with it.
Calculators I have used so far come out at 2 bulk bags of gravel and 6 bulk bags of topsoil to fill both (one on each side of the garden) 😳
But my question is does 15cm gravel and 40cm soil sound correct. Should I be just using topsoil/mixing with compost?
https://gardening.which.co.uk/hc/en-gb/articles/360002423239-Soil-for-raised-beds
The calculator provided by K67 suggests 3 bulk bags will be necessary for each bed.
One word of warning, there have been many scare stories reported recently of manure contaminated by weed killers so practise diligence before you buy. Asking for recommendations of local suppliers on the Nextdoor.com website is always a good move.
PS Here’s a supplier of soil for raised beds. It was just the first one I came across when looking on Google.
https://www.norfolktopsoil.co.uk/product/raised-bed-allotment-soil-mix/
You can fill the bottom with garden compost, someone suggested asking the neighbours for the contents of their green bins but you don't want anything diseased, lawn turf or cardboard but they will rot down in time so beds will need topping up but you can do that by mulching every year.
40cm should be sufficient for most plants so is the gravel cheaper than the soil?
Bulk bags of topsoil/compost I have seen so far are around £80/90 and gravel only £40.