Which aggregate/sand should I use to improve drainage?

Post Reply
ourarka
Posts: 566
Joined: Tue Jan 11, 2011 10:01 pm
Location: East Sussex

Which aggregate/sand should I use to improve drainage?

Post by ourarka » Sat Apr 13, 2013 2:57 pm

This are is soon going to be my arids section, and before putting the weed fabric down I want to dig something in to improve the drainage further. It isn't bad now, as it is a raised bed and has some old stuff in from previous rockeries, but what would be best to dig in?
Attachments
photo.JPG


User avatar
Vagetarian
Posts: 939
Joined: Fri Aug 12, 2011 12:37 am
Location: Norfolk

Re: Which aggregate/sand should I use to improve drainage?

Post by Vagetarian » Sat Apr 13, 2013 7:52 pm

I'll go with grit. Sand is OK but it actually holds a surprising amount of water as it sticks to the surface of things and sand is pretty much all surface area with tiny gaps in between. Grit should help create some little air pockets. Also, not suggesting your bed has clay in it but, sand + clay = bricks. :lol:

I think horticultural grit and sand is washed so I'm not sure but you might want to rinse aggregates from a builders merchant, which are probably a lot cheaper.


User avatar
Mr List
Posts: 5075
Joined: Thu Jan 20, 2011 9:00 pm
Location: Leeds,West Yorkshire

Re: Which aggregate/sand should I use to improve drainage?

Post by Mr List » Sat Apr 13, 2013 7:58 pm

aldi were selling bags of little bits/chips of granite cheap.

when I saw them I thought 'they would be great to use for a grit mix'


User avatar
Dave Brown
Site Admin
Posts: 19686
Joined: Sun Jul 09, 2006 10:17 am
Location: Chalk, (Thames Estuary) Kent, England 51.5N 0.3E
Contact:

Re: Which aggregate/sand should I use to improve drainage?

Post by Dave Brown » Sat Apr 13, 2013 8:16 pm

I spend 3 years messing adding stuff trying to turn a clay based soil into an arid area, with disastrous results :roll: everything rotted several times over. I then gave up and dug the lot out, using a ballast, pea gravel mix, with a tiny bit of loam. This worked :wink:
Best regards
Dave
icon_thumright
_________________________________________________
Roll on summer.....
http://www.hardytropicals.co.uk


ourarka
Posts: 566
Joined: Tue Jan 11, 2011 10:01 pm
Location: East Sussex

Re: Which aggregate/sand should I use to improve drainage?

Post by ourarka » Sun Apr 14, 2013 7:16 am

Thanks - this area is not particularly clay-ey - lucky that only a few spots in the garden have much significant clay in them. It is pretty decent soil to be honest so sounds like a bit of grit should help do the trick.


User avatar
multim
Posts: 463
Joined: Wed Jun 27, 2012 6:28 pm
Location: South Bucks UK

Re: Which aggregate/sand should I use to improve drainage?

Post by multim » Sun Apr 14, 2013 9:01 am

I've found that horticultural grit works best for me...and my arid loving plants.
Growing the improbable - not the impossible


User avatar
multim
Posts: 463
Joined: Wed Jun 27, 2012 6:28 pm
Location: South Bucks UK

Re: Which aggregate/sand should I use to improve drainage?

Post by multim » Sun Apr 14, 2013 9:08 am

Just a quick P.S. to my last message. If you are putting a membrane around the plants, it's best to cut a circle around the base of the plants to allow for air to circulate and moisture evaporation to occur. This prevents a stagnant root ball/planting hole as the plants need to breath. Any weeds can easily be pulled out.
Growing the improbable - not the impossible


User avatar
Dave Brown
Site Admin
Posts: 19686
Joined: Sun Jul 09, 2006 10:17 am
Location: Chalk, (Thames Estuary) Kent, England 51.5N 0.3E
Contact:

Re: Which aggregate/sand should I use to improve drainage?

Post by Dave Brown » Sun Apr 14, 2013 4:27 pm

I don't use a membrane at all as it hold in moisture which you don't want ;)
Best regards
Dave
icon_thumright
_________________________________________________
Roll on summer.....
http://www.hardytropicals.co.uk


User avatar
karl66
Posts: 2618
Joined: Mon Jul 11, 2011 6:39 pm
Location: halesowen. west midlands

Re: Which aggregate/sand should I use to improve drainage?

Post by karl66 » Sun Apr 14, 2013 5:11 pm

I also agree ballast is great to add into the mix for raised bed's although how much you need depends on what exact plants your planting!, my latest sleeper bed will have various aggregates thown in including broken up tiles, ballast, quality screening soil, compost, & lots of 10mm pea gravel. I can you old limestone chippings off the roof's i strip off but i'm not to sure whether limestone would have any adverse effects on certain plants although most of it will have been washed as its been on some roofs donkey's years?. karl.


User avatar
Dim
Posts: 1425
Joined: Wed Jul 06, 2011 5:49 am
Location: cambridge

Re: Which aggregate/sand should I use to improve drainage?

Post by Dim » Sun Apr 14, 2013 6:02 pm

I've read that if you use a membrane, you wll have no earthworms in your soil
Last edited by Dim on Sun Apr 14, 2013 7:00 pm, edited 1 time in total.
"We don't live off the food that we eat,
We live off The Energy IN the food we eat!!!"
- Dr. Carey Reams, Phd. in Biophysics and Biochenistry


User avatar
Vagetarian
Posts: 939
Joined: Fri Aug 12, 2011 12:37 am
Location: Norfolk

Re: Which aggregate/sand should I use to improve drainage?

Post by Vagetarian » Sun Apr 14, 2013 6:06 pm

Limestone is calcium carbonate and it will gradually raise the pH.


User avatar
Yorkshire Kris
Posts: 10144
Joined: Wed Dec 16, 2009 8:59 am
Location: Rural South Wakefield, Yorkshire Lat 53.64 Long-1.54

Re: Which aggregate/sand should I use to improve drainage?

Post by Yorkshire Kris » Wed Apr 17, 2013 9:22 pm

I would just use 90% grit/rock/rubble etc with only 10% soil or loam. Adding loads of grit to normal to heavy clay soil will still be too moisture retentive for most arids like agaves.


Post Reply