How deep to fill a planter

Cactus_Flowers

I hope I manage to explain this correctly - very much a novice gardener, so let me know if you have any questions!

I have a big built planter in the garden, which is currently full of building rubble and assorted rubbish. I've been intending to empty it out and fill with soil so I can get some plants in, but I'm wondering if I need to completely empty it or if I should leave it half (quarter? three-quarter?) full of old roof tiles and bricks to both provide some drainage and also means there's less soil that I need to buy.

Does anyone have a view on this? The planter looks to be about 70cm deep and I haven't reached the bottom underneath the rubbish yet, but I'm assuming it's old concrete under there and that there's no connection from the planter to the actual earth. What would happen to these (hypothetical so far) plants if they only have 1 foot of soil instead of 2 feet? I'll probably be looking at decorative flowers rather than edible vegetables, if that makes a difference.

fatbelly

So you're just talking about annuals and perennials, not shrubs or trees?

In that case it's the top six inches that needs to be fertile and that's what you need to invest in. 6-12 inches, less important. Over 12 inches, keep the rubble. Is there some way for water to escape? Because a 70 cm planter can still get waterlogged.

Cactus_Flowers

fatbelly said:

So you're just talking about annuals and perennials, not shrubs or trees?

Yes, hoping to get perennials and maybe a small shrub but nothing that grows too big - it's very close to the house and will block all light if anything's too big.

fatbelly said:
In that case it's the top six inches that needs to be fertile and that's what you need to invest in. 6-12 inches, less important. Over 12 inches, keep the rubble. Is there some way for water to escape? Because a 70 cm planter can still get waterlogged.

Thank you so much! That is really helpful info, and means I don't have to clear out much more! I'll look to see if I can chisel a hole at the bottom, I hadn't thought about it being waterlogged before

MyRealNameToo

Cactus_Flowers said:

I hope I manage to explain this correctly - very much a novice gardener, so let me know if you have any questions!

I have a big built planter in the garden, which is currently full of building rubble and assorted rubbish. I've been intending to empty it out and fill with soil so I can get some plants in, but I'm wondering if I need to completely empty it or if I should leave it half (quarter? three-quarter?) full of old roof tiles and bricks to both provide some drainage and also means there's less soil that I need to buy.

Does anyone have a view on this? The planter looks to be about 70cm deep and I haven't reached the bottom underneath the rubbish yet, but I'm assuming it's old concrete under there and that there's no connection from the planter to the actual earth. What would happen to these (hypothetical so far) plants if they only have 1 foot of soil instead of 2 feet? I'll probably be looking at decorative flowers rather than edible vegetables, if that makes a difference.

What are you planting? 

That will determine how deep their roots go and there is little need to go below where their roots will go with soil unless you want the flexibility of putting in deeper plants without having to empty the thing again. 

twopenny

I would get the concrete out.
It can leach lime into the soil and affect the plants.
https://concretecaptain.com/is-concrete-bad-for-plants/ 

When I had some paving done it was right up to my established lavenders and they suffered badly.
However I moved them 6" away but 3 still died. One is ok.

I'd still be inclined to bite the bullet and put in 2' of a mix of soil and compost for the best results because once you get around plants your enthusiasm will get you carried away. Ooo I like that I kind of way 😉

It would also be worth putting upside down empty plastic bottles in beside the plants so you can get water down under the surface.
For my really big pots I got carried away and sliced up plastic plumbing pipes with holes drilled around and that worked a treat.
Bit of a pain but it lasts forever.
The ones I didn't do have failed in this heat. The ones I did are surviving well.