Soil for my new raised beds

[ali_uk_1]

Hi,

I’m having some raised beds built to house my plant collection, and I’m hoping for your advice on the compost/soil mix to use.

On the south facing (sunny) side, I’ll be planting general alpines (eg. campanula, silene, iris, aster, celmisia, dactylorhiza etc). So far, I’ve put in the chalky (alkaline) soil that was dug out to create the patio. On the north facing (shady) side, I’ll be growing shade loving plants (obviously!! ) (eg. arisaema, mini rhododendron, epimedium, anemone, hepatics, corydalis etc). I’ve put in a mix of neutral topsoil and composted bark, bought in from a local company.

My questions are:

• Do I need to add grit, and/or top soil to the alpine side? The soil in there is course with many lumps of chalk, it seems quite open and dry at the moment (but then it hasn’t rained here properly for ages!)
• Where do I buy a large quantity of the 3-5mm grit for the topdressing, and mixing into the soil if necessary? I’ve been to 4 builders merchants and they don’t sell anything less than 10mm in size. The tiny bags they sell in the garden centre will cost a fortune, and I’ll need hundreds of them!
• Do I need to add anything else for the shady side? Peat maybe, or a peat substitute?

Any advice on adding fertilizer? I was thinking of mixing in bonemeal – is that a good idea?

Thanks in advance for any and all advice. This is the first time I’ve done anything like this – all my plants are currently grown in pots, so this is a big change for me!

Emma.

[tonyg]

Hi Emma
Exciting times!  You will see great changes in your plants when you release them into these raised beds, even if you do nothing more than you have already done.  In my experience many plants simply take off when given more space.  There will be some which sulk, perhaps less suited to your conditions but that is just a part of the learning experience.
I have never gardened on a chalky soil so I cannot offer first hand experience re Q1.  However I assume that what you have is free draining, perhaps with a tendancy to become very dry in summer?  If so you may well be best to leave it as it is.  If it is a clayey soil adding some extra grit or very sharp sand will reduce the tendancy for it to become 'claggy'.  Humus is also good for improving clay soil but it breaks down quite quickly so the effect is not a long lasting as sand/grit.  If you think the soil is poor then adding some topsoil to improve it is a good idea.  Take a look at what grows in other gardens locally, there should be some clues as to the qualities of the soil.
How large a quantity of topdressing grit?  The garden centres here sell 25L bags.  Have you tried large pet/poultry suppliers?  I am told that some grades of chick grit are the right size.  I have recently switched to using larger grades (slate is corrently my favourite) as I have fould that this reduces weed seeding.  3-5mm grit can seem like cat-litter to some cats which has also been an issue.  These are available in 25L bags or from builders merchants in larger quantities.  It can be worth shopping around, quality and prices vary, you might get a discount from GCs if you want 10 or more bags of the same stuff.
Shade is in short supply here!  But I will do exactly as you have over the winter in an area where I plan a similar plant mix.
Fertilising with bone meal should be OK.
Good luck and let us know how it goes ... Pictures?

[Gerry Webster]

Emma - as regards grit, have you tried Chandlers Builder's Merchants near Ringmer?  Though I haven't bought any for years they used to sell 'Chichester Grit' - 6mm down. It was quite cheap. Better for digging in rather than top-dressing I would think.

[ali_uk_1]

Thank you for your replies.

Tony - exciting times indeed! I had been thinking about using the slate chippings, but is that a good idea on the sunny side - I thought dark slate would get very hot in the summer and the alpines like to keep their root run cool? Your point about cats using the small grit as a litter tray is something I really want to avoid! 

Gerry - thanks for the tip about Chichester grit, I'll check that out at the weekend.

Here are a few pics of how things are progressing so far:

how things looked before the work started


during the building


almost there (how things look at the moment)


This is a pic of the chalky soil. Things grow in the gardens here well, but this soil is much more chalky because it's been dug up from under the patio. Do you think adding topsoil to it would be a good idea, it looks a bit poor to me.

[ali_uk_1]

How come my photos don't show as thumbnails, can someone tell me what I've done wrong? Thanks.

[Maggi Young]

When you load photos from an outside "place", such as photobucket, they come in full sized , Emma.

[Lesley Cox]

Or if you are using the "attach" method of uploading, use attachthumb= rather than attach, with the relevant number of the picture and in square brackets.

I would be inclined to add a little slow release fertilizer such as Osmacote, dug well in, to root level. Also, I don't think Celmisias are lime lovers. The reverse, in fact.

[Ragged Robin]

Emma, your dry stone walling looks terrific! Raised beds are wonderful for Alpines as you can see them close up and enjoy the huge variety of leaf shapes and flowers.  The only thing is you need plenty of them 

We created a raised be here and backfilled with the soil (sandy moraine) that was dug out like you and I added lots of bought top soil and last Autumn added leafy humus lightly dug in on top.  The worms did the work!  This year I have a top dressing of grit which drops into the soil when I plant an alpine. 

Having never grown Alpines before it is an enormous challenge to find the requirements they like and generally I have found that so long as the roots are cool and well drained against, under or in a rock crevice they love be warm on top - shade lovers not included!  I have also planted miniature bulbs which pop up in the Spring for a great display and am planning to extend that throughout the year.

You won't be short of ideas or advice on this wonderful Forum 

Good luck with you new venture 

[tonyg]

Wow!  Seriously impressed
That is a remarkable transformation.  Looks great. 
The chalky 'natural' does look as though it will be free draining.  As to 'poor' I am not sure how much that will matter, many alpines grow in places with soil that makes that look rich!  However the climate in the mountains will be rather different to that on the coast of S England, so you may want to add something to help with moisture retention.  Soils over limestone are generally species rich as the lime helps to make some nutrients available in larger quantities.  However advice from people who garden with similar soil will help you (what do you think Gerry W?)
Looking forward to hearing (and seeing) how it goes.

[Luc Gilgemyn]

A very good looking construction Emma !!
It really looks ideal for its purpose !
Don't forget to do some planting in the rock fissures of the retaining walls.. 

Good luck with the project - we'll be following your experiments with avid interest ! 

[Gerry Webster]

The chalky 'natural' does look as though it will be free draining.  As to 'poor' I am not sure how much that will matter, many alpines grow in places with soil that makes that look rich!  However the climate in the mountains will be rather different to that on the coast of S England, so you may want to add something to help with moisture retention.  Soils over limestone are generally species rich as the lime helps to make some nutrients available in larger quantities.  However advice from people who garden with similar soil will help you (what do you think Gerry W?)

Tony  - Emma obviously gardens in a different part of Brighton to me. I am on clay whose untreated texture is rather like Cheddar cheese; the chalk is at least a metre down.  So my experience would be of no help whatsoever. 

[ali_uk_1]

Thanks everyone for the replies and advice, it's great to get your opinions.

[Paul T]

Stunning, Emma.  That is some accomplishment.  Congratulations of creating such a great feature.  I am jealous as anything. 

[ali_uk_1]

Fermi asked me for an update on my raised beds, so I'm posting a few new photos.

Filling the raised beds was a lot harder work than I realised it was going to be! I ended up having to buy about 2 tonnes of soil and gravel to add to the soil I already had from the patio area. The comapny could only deliver it to the public road at the side of my house, and I had to shovel all of it over the garden wall in buckets, and then mix it before I could fill the beds - it took me full 3 days (and I had help!!)

Here is an overall view:



A view of the sunny side:



and a view of the shadey side:



I tried to build a small crevise area. I think I placed the stones too far appart, but I don't think it's too bad 



I also built a small raised area, I know it's all raised but I was trying to get different heights to make it a little more interesting!



I am surprised how well established it looks already, it's been less than a year since I planted most of the plants, and they have grown very well - just as you said they would (thanks Tony!). I also thought I had far too many plants, and would have many left over with no space for them, but that wasn't the case. In fact I still have spaces, I know they will grow over the years but obviously most of them are going to stay small. I never seem to have trouble buying more though The other thing I'm pleased about is that plants in the garden are much easier to look after, in fact I hardly have to do anything at all, not even water them. The soil I bought in is a mix of clay, gravel and 'black fen soil', and keeps quite moist but not water logged. I'm very pleased it worked out well, because it was more luck than judgement!

Just a couple more pics of plants that were still looking good last weekend - roscoea Red Ghurka, and a couple of tigridia.





I've been waiting for the aconitum japonicum to flower all year, the buds have been slowly developing since about april, it's almost there!



(fingers crossed I've added the photos so they show up properly!)

[Lesley Cox]

Everything's looking great Emma, tremendous growth in a short time so you'll be really pleased.
I would say at a guess that however much soil/compost one thinks one needs, it is NEVER enough and more has to come from somewhere. Same with rocks.

I hope that bunny doesn't climb. A (wild) rabbit has muched his way through most of my spring bulbs in recent weeks, especially Narcissus vars and the reticulate irises.