Which aggregate/sand should I use to improve drainage?
Which aggregate/sand should I use to improve drainage?
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?
Re: Which aggregate/sand should I use to improve drainage?
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.
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.
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.
Re: Which aggregate/sand should I use to improve drainage?
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'
when I saw them I thought 'they would be great to use for a grit mix'
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Re: Which aggregate/sand should I use to improve drainage?
I spend 3 years messing adding stuff trying to turn a clay based soil into an arid area, with disastrous results 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
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Dave
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Dave
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Roll on summer.....
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Re: Which aggregate/sand should I use to improve drainage?
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.
Re: Which aggregate/sand should I use to improve drainage?
I've found that horticultural grit works best for me...and my arid loving plants.
Re: Which aggregate/sand should I use to improve drainage?
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.
- Dave Brown
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Re: Which aggregate/sand should I use to improve drainage?
I don't use a membrane at all as it hold in moisture which you don't want
Best regards
Dave
_________________________________________________
Roll on summer.....
http://www.hardytropicals.co.uk
Dave
_________________________________________________
Roll on summer.....
http://www.hardytropicals.co.uk
Re: Which aggregate/sand should I use to improve drainage?
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.
Re: Which aggregate/sand should I use to improve drainage?
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.
Re: Which aggregate/sand should I use to improve drainage?
Limestone is calcium carbonate and it will gradually raise the pH.
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Re: Which aggregate/sand should I use to improve drainage?
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.