Ideal Bed, depth, drainage etc ... ?

padi89

At the moment i am making a bed for planting it will be a couple of small trees, some small shrubs and flowers. What i want to know is how deep to dig ?
My garden is a lovely gift from the builders, a few inches of topsoil (if you can call it that) before i hit rubble and hardcore

Anyway, so far i have gone down 12" and i have a base of rubble/hardcore, the bed will be raised another 6" so altogether i am at 18".

What i want to know is do i need to dig any further ? Is this base of hardcore/rubble a bag thing ? The lawn here was full of moss but it still drained as far as it was never saturated, in fact it dried quickly.

Also, do i need to put drainage in the bed, would i need to backfill with a few inches of rubble and then soil on top?

Any input is much appreciated, thanks in advance.

lalorm

Hi
I was given the same gift by our builder!! Well, if it's pure hardcore and rubble, then, the only solution is to dig it out. You don't need to dig too deep, but the hole should be big enough so you have at least half the diameter of the pot around the root ball and a few inches below free for compost etc. This will help give the plant room to spread it's roots out. Trees, will manage fine and get through very heavy soil. I planted trees and shrubs in heavy soil, but I dug in a lot (and I mean a lot) of organic matter in to breakup the clay in my garden, but the roots have gone long past where I dug and planted it. sprinkle some blood fish and bone organic fertiliser into the hole to help stimulate root growth and they should be fine.
Also, if it's very heavy soil/hardcore, get a pickaxe. Makes the job alot easier than using a fork. Post a pic of the site and plants if you like and maybe we can offer some more advice.
Cheers
Mike

Sonnenblumen

OP very few plants including trees will thrive in poor soil. On the contrary poor soil and inadequate ground preparation are probably the more likely cause for plants failing to develop.

Most plants require good soil and ground should be freshly dug, the planting hole should at least be double the size of the rootball.

If you prefer to build Raised beds, the depth should be at least 225mm(9") but 450mm (18") is more typical.