I recently erected a 36x16ft heated poly tunnel with the aim of eventually having a small scale mail order nursery as a second job/hobby, and am in the process of repotting several thousand seedlings which have made it through the winter and are plumping up again.
Because I'm just moving from small scale hobbyist growing to something much larger however, I need to make economies of scale, and using endless bags of cat litter as a substrate isn't really feasible. Instead I'm thinking of using bulk bagged crushed clay bricks mixed with sterilised sandy top soil - a cheap alternative to tesco litter and john innes no 2. I've seen crushed brick mentioned as a substrate in some Czech cacti literature, but was wondering if anybody here had used it and with what results?
I've found what looks like a good source here : http://www.stonewarehouse.co.uk/gravel- ... ral-5-14mm
If anybody knows where else it is available please post, or if there are obvious bulk alternatives to brick which I haven't thought of.
I'm a little concerned a lot of stuff available is likely to be contaminated with cement/render etc., which would end up raising the ph a lot.....
When I started cultivating cacti & succulents, in the 1950's, crushed brick was a recommended ingredient of the substrate. It is very effective in keeping an open compost and in its pure form has a minimal effect on the ph of the overall mix. Unless you can get a source of "pure" crushed bricks the contaminants would potentially cause you problems, however. On a small scale it is easy to guarantee that the crushed bricks are free of contaminants but I don't know how you would guard against this with a large commercial load.
Rod Smith
Growing a mixed collection of cacti & other succulents; mainly smaller species with a current emphasis on lithops & conophytum.
Buxbaum in his book "Cactus Culture Based on Biology" was one of the early adopters of broken brick but as I recall he then digested the broken brick with weak acid to remove the alkalinity. Also these days many bricks are not just clay but may include other adulterants.
Can't say I found raising seeds on Cat Litter all that successful though.
Endean before Buxbaum used to use baked clay and in fact sell it for cactus raising. I believe he dug it up from his garden (OK if you are in a brick clay area) and used to roast it on a sheet of steel or corrugated iron over a bonfire.
I believe some also use pumice for seed raising, but that is even dearer than cat litter.
Nottingham Branch BCSS. Joined the then NCSS in 1961, Membership number 11944. Cactus only collection.
I would visit my local brick works and talk to them about what possible contaminants there might be. Assuming you get the all clear, brick works have an on-going supply of reject bricks. They are cheap to buy in bulk or even free-of-charge. I have one within a mile of my nursery and they've always been helpful. Crushing the bricks or half bricks to a small and standard size would be something to then consider. (Becky would insist on doing it by sledgehammer but there must be a suitable small machine you could hire for a day.)
Or you could start up an independent supermarket and get Tesco's finest at trade prices!
I should have said you can often buy material similar to Tesco Cat Litter (Diatomaceous Earth or 'Diatomite') sold in large bags from garage supplies to absorb oil spills from garage floors. But again as with cat litter you have to make sure it is the correct type as several different oil absorbent materials are sold and most garage suppliers would probably not know the difference.
As Carl said elsewhere they have now updated the Tesco bags, therefore the original Bonsai site has also been updated to include this:-
They also sell simmilar products to the cat litter as something called Dry stall but I'm yet to find a supplier of the correct calcined clay product I feel it might be more common in the US?
Thanks all for the very helpful replies, much appreciated.
I've made a quick google search for a brickworks in my neck of the woods (Devon/Somerset border) and can't seem to find anything, which is frustrating, since Iain's suggestion of calling by a brickworks sounds very sensible. I'm thinking I might see if I can get a small sample of the crushed brick from the supplier I listed and then pH test it (they also list crushed terracotta tiles, which sound potentially good).
I'll investigate diatomaceous earth as an alternative too, the stuff I'm familiar with is a fine powder though, so I'll see if I can get hold of some of the granulated sort.
The product Carl mentions looks excellent also - but as he says: I can't find a uk seller....
Conrad: A quick search has failed to highlight our local brickworks, yet it is still very much in business. A few phone calls to bricklayers or house builders in your area might provide some leads. If you have access to a lorry or transit van, travelling beyond your area might still prove to be cost effective because you won't pay much for reject bricks.
Do you have access to CactusWorld from 2008-2010? There is a series of 4 articles by Ray Allcock covering soil stuff in detail and the use of brick is discussed quite a bit as it's one of the ingredients he favours.
I've used 'eco gravel' which was really rough! with lots of bits of concrete, tile, plastic in for my outdoor cactus rockery. It hasn't been a great success (which is why I haven't posted anything about it on the forum before) and I wondered if it was to do with alkalinity. It's had 4 or 5 years of rain on it now and the plants are still not doing great so perhaps that's not the sole problem in my case. I actually think that the medium is too porous!
If you look at commercial nurseries, many are succeeding planting plants in plain old multi-purpose compost. It's cheap and, provided the plants are only in it for a couple of years, it doesn't 'go off' or go hard. If you'd prefer your normal soil, don't forget that for mail order, most of your soil will stay with you and you could recycle it. This might not be a good idea for multipurpose compost but is fine if you grow in, for example, 50:50 grit and cat litter. Initial investment perhaps but not much ongoing costs.
Phil Crewe, BCSS 38143. Mostly S. American cacti, esp. Lobivia, Sulcorebutia and little Opuntia
Phil's suggestion above of using multi-purpose compost is good. Following on, I wasn't joking in my first reply about using peat. It's vastly superior to multi-purpose compost (which covers such a wide range of stuff adding up to anything from "reasonably good" to "dreadful" - the best of which usually has peat included). I know it's frowned upon by many - and I don't use it for our succulent collection - but if I was growing commercially it would be my first choice. Look at the European growers of vast numbers of plants, if you want evidence of success/suitability. Customers can then remove and re-pot according to their individual preferences.
Major additional advantage: it's easy to purchase in large quantities, delivered to your site. Fluff it up and fill your pots. Simple.
And a note from me as an environmentalist. Greenies overdo the "don't buy/use peat" argument, targeting guilt-ridden middle class consumers. There have been plenty of reputable suppliers since 1981, aware of the environmental situation long before it was hyped up by greenies and the late Geoff Hamilton (possibly the best Gardeners World presenter, but a failed nurseryman, landscaper, and garden centre owner).
with the aim of eventually having a small scale mail order nursery as a second job/hobby, and am in the process of repotting several thousand seedlings which have made it through the winter and are plumping up again.
Initial investment perhaps but not much ongoing costs.