Ballast (for raised beds)

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fgtbell

Ballast (for raised beds)

Post by fgtbell » Sat Jan 15, 2011 12:59 pm

This seems to be the part of the forum where we can discuss horticultural supplies like sulphur, moss, compost - so here goes:

I have heard that planting agaves, aloes etc., outside is best done in pure ballast (for drainage). However I have looked at a few builder's merchants and it is very confusing:

What grade of ballast is best ? (it seems to be availabe in 10mm and 20mm sizes) - and does it matter much what it's made of ?

Also... most photos of ballast on builder's merchants' websites show a mix that is mostly sand, with some stone. I don't want any sand in the mix at all, since it holds too much water

Does ballast always involve a mix of sand and stone ? If so then I think I should be looking for chippings or gravel of some sort. Again - any recommendations ? Thanks !

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Dave Brown
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Re: Ballast (for raised beds)

Post by Dave Brown » Sat Jan 15, 2011 3:50 pm

Hi Francis,

All the ballast I have seen is mainly sand. I have the 20mm, but I put rough crushed gravel under it to add to the drainage. Sounds what you are after is crushed brick and rubble, but where you would get that from I don't know.

You have to be a bit careful of having nothing that holds nutrients, as I found Agaves grew far better in ballast with a sprinkling of JI No3, than just in gravel :wink:
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Dave
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sanatic1234

Re: Ballast (for raised beds)

Post by sanatic1234 » Sat Jan 15, 2011 4:44 pm

I was also going to suggest John innes No3, with gravel added to it as john innes has grit added to it anyway which will improve drainage. I will be planting my agave's in that come mid spring time. :wink:

fgtbell

Re: Ballast (for raised beds)

Post by fgtbell » Sun Jan 16, 2011 9:46 pm

Thanks very much. I try to work in a bit of slow release fertiliser anyway from time to time. It is easy to top up with a bit of JI, etc., as required - but harder to improve drainage unless it is there from the start.
Last edited by fgtbell on Mon Jan 17, 2011 5:56 pm, edited 1 time in total.

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Dave Brown
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Re: Ballast (for raised beds)

Post by Dave Brown » Sun Jan 16, 2011 10:13 pm

San, JI on its own is nowhere near well drained enough, and would need at least 50% sharp sand/grit added, if not more. I use John Inns No3 as it is used at about 1 part per 200 or so. If you are using a much higher ratio it will be too strong for an Agave. :wink:
Best regards
Dave
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Roll on summer.....
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sanatic1234

Re: Ballast (for raised beds)

Post by sanatic1234 » Sun Jan 16, 2011 10:50 pm

Thanks for letting me know Dave, i will get some sharp sand/grit to add to it, then. :) also may be add some perlite to it as well.

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