Height of soil level in planter

boragejohnson

I have a sandstone blockwork planter I'm just about to fill for sun loving plants.  I've been building the soil level so that it is now about 10-12cm from the rim - what would you suggest for the ideal final fill level - how far below the rim is the best balance? 

I don't want to lose soil etc overboard onto the patio, but I also don't want excessive shading by the planter walls.  It's also in a pretty exposed location close to the coast, and approx. 1 metre high. 

Fairygirl

It'll need to be at pretty much the same level as the rim. It'll settle anyway over time and will need topping up every year or so. 
Most importantly though - the plants need to be put in at that level if they're permanent, otherwise they'll end up too low and if you just pile more soil/compost over them, you'll end up burying them, and probably losing them. 
Most spring bulbs would be ok though, and it's not a problem if it's annuals going in it. 

Nollie

I’m just about to fill my latest raised bed and would raise Fairygirl a couple of inches 😆 

I plan to heap it higher than the rim, holding the soil in place with temporary bits of wood. I won’t be planting it up until May as it’s better to allow it to settle a little initially. It will doubtless still need topping up next year but I’m hoping by not as much this time.

If you have a good proportion of topsoil it’s better, but if it’s mainly organic matter like compost and manure, that sinks incredibly fast. You do want to avoid burying plants or exposing their rootballs as the soil level shrinks around them - having to dig up and replant at a higher level is a pain!

Fairygirl

Yes - if you're not planting straight away, a bit higher is better @Nollie
Soil certainly stays in situ better, while compost [in particular] will drop away a fair bit.
It comes down to the type of plant and their ideal growing conditions too. I add a bit of general compost each year, usually the spent stuff from sweet peas etc. The clematis and bulbs don't mind that, but I'm more careful around any perennials. 

I know what you mean about digging up and replanting too. Avoiding that is always preferable   

KT53

Lots of different thoughts on that question I see, but I'd keep it an inch or so (2.5 to 5cm) below the top.  That makes watering easier.  Top up if/when the compost settles.

rowlandscastle444

Monty Don always makes me smile, when he adds

" . . . and add a layer of horticultural grit, to avoid splashing soil onto the plants, when watering."

He must get through loads of the stuff, but I'll admit, it DOES make a difference. Looks good too.

boragejohnson

Thanks everyone, I've now got a fair idea.  No compost or manure has been added yet, and the vast majority of the bed bulk will be topsoil, grit and further down, perlite, so seems as though my bed won't drop too far.   I'm going to try the grit on top too, Monty style - I better stock up on the grit...   I notice Carol Klein uses a lot of grit too.

bcpathome

What did we do before grit ? My parents didn’t do anything except stop up one of the drainage holes if mor than one was provided ,certainly didn’t put ‘ drainage’ grit or little bits of white ‘ stuff’ in the soil . Grit was what you washed off spinach .

rowlandscastle444

boragejohnson said:

Thanks everyone, I've now got a fair idea.  No compost or manure has been added yet, and the vast majority of the bed bulk will be topsoil, grit and further down, perlite, so seems as though my bed won't drop too far.   I'm going to try the grit on top too, Monty style - I better stock up on the grit...   I notice Carol Klein uses a lot of grit too.

When I ordered my first bag of horticultural grit, online, I thought a bag of 20kg would last a long time. 
How wrong I was!!

Nollie

I agree with Rowland there, it goes nowhere! Horticultural grit is good for mixing in and topping off, but will work out very expensive in the quantities you would need for a large raised planter. Think I would be heading to the builder’s yard for sacks of small grade gravel and mixing in and topping off with that instead.

Depending on the topsoil (if it’s heavy clay, for example, like mine) you may still need some compost in the mix, even for those that cope well in lean conditions. Clay soil and grit just clumps together and drains poorly without being loosened by organic matter - any old cheap mpc will do.

Drainage of your raised bed structure is also v important, is the base open to the earth and/or have you got sufficient weep holes drilled in near the base? Otherwise no matter how free draining the mix, it can still end up filling up like a bathtub! 

Busy-Lizzie

I agree with @KT53, compost up to one or two inches from the top to allow for watering then I top it up each year.