Mulching with grave rock?

[Raulglezruiz]

I recently built a side brick wall along the property, I end up with lots of this little rock used in the mixture with the sand and cement to pour it in the rebar reinforcement of the wall, since I don't have use for it I was considering use it as a mulch for keeping away weeds from the trees, would this be OK or damage the tree, soil, or something else? I'm thinking it could block oxygen into the soil but I'm not sure any guess?

[fruitlovers]

No harm mulching with rock. Actually helps to conserve moisture in the soil. Only problem is if you want mow over it?

[BajaJohn]

I use gravel mulch under mango trees and around cactus with no problems. The few weeds that come up only take an occasional few minutes to remove by hand. My climate in Baja California has only a few rainy days (if any) per year so the surface soil stays very dry and inhospitable to weeds.
The mangoes have been great this year so the trees must be OK with it.
One minor problem is that the gravel tends to migrate if it isn't contained or constantly raked back into position.

[Jose Spain]

When I have not organic mulch available, I use expanded clay (arcilla expandida):



It works both as mulch and for drainage. Roots love to expand through it, and it keeps the humidity very well. Only thing to have into account is that is 10 times more expensive in garden centres than in building supplies store (and the stuff is exactly the same), at least here in Spain: 13.20 gallons cost around 4,5€ in the second ones, and 2,6 gallons 6€ in the former.

[fruitlovers]

Don't know what this expanded clay is? Does anybody know the english name? Is it available in the USA?

[zands]

Don't know what this expanded clay is? Does anybody know the english name? Is it available in the USA?

Expanded clay has a Wikipedia entry. Interesting stuff
https://en.wikipedia.org/wiki/Expanded_clay_aggregate

Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a light weight aggregate made by heating clay to around 1,200 °C (2,190 °F) in a rotary kiln. The yielding gases expand the clay by thousands of small bubbles forming during heating producing a honeycomb structure. LECA has an approximately round or potato shape due to circular movement in the kiln, and is available in different sizes and densities. LECA is used to make lightweight concrete products and other uses.

also called clay pebbles
https://www.amazon.com/s?ie=UTF8&field-keywords=Expanded%20clay&index=blended&link_code=qs&sourceid=Mozilla-search&tag=mozilla-20

[fruitlovers]

Thanks Zands, BTW compare with the price in Spain. The price on Amazon is $10 for 2 pounds! Anybody seen this sold as a building material?

[Jose Spain]

Thanks Zands, BTW compare with the price in Spain. The price on Amazon is $10 for 2 pounds! Anybody seen this sold as a building material?

For gardening prices are crazy. But expanded clay is sold to be mixed with concrete, and is exactly the same material (prices I  commented before for gardening and building actually are from the same store, two different sections! I don't know if is commonly used in USA though, but building material store is really the only option I would consider.  I forgot to say that is really light, it floats. You can easily rise a 50 litres bag full of it.

[fyliu]

I think the reason it's expensive for gardening is that it's sold for hydroponics. Weed growers pay more for stuff.

[DimplesLee]

It's hydroton or hydrocorn in gardening centres Oscar. I use the 2cm to 3cm diameter LECAs for hydroponic pots (so they don't fall off the pot holes) but the smaller rejects are cheaper - the broken ones or those that didn't expand too well they're like little beads around 5-15mm diameter all mixed in one bag - I put those in flood and drain grow beds instead. The LECAs that failed to properly expand (can't hold too much air inside the balls) don't usually float. You can rinse them in a bin of hot water and let it stand for half an hour or so and the ones that float get used for hydro growbeds but those that sink go into the pond


I've heard some tradies call it exclay (expanded clay) pellets and yes - they're pellet shaped instead of the normal round balls for garden use. It's primarily for insulation and comes in standard 25kg bags at our local Bunnings but haven't checked the price. Had some leftover and tested the pH - both exclay pellets and hydroton are in the neutral range.


IMHO since the clay is strip-mined in "poor" countries and shipped halfway across the globe - a bit pricier alternative would be growstones? From recycled glass.

[behlgarden]

Wouldnt coarse small rocks of decomposed graite do the same thing?