Volcanic rock as mulch, good? bad?

[JT in Japan]

I'm wondering if there are particular benefits to putting a layer of volcanic stone (?) in place of traditional mulch. I like the color, for one. it'll keep my cats out of the beds, second. It should really grab some heat for the ground in January and February, when I need it. But is it good for the palms?

Thoughts?

[Tassie_Troy1971]

would be ok but no organic benefits

[Mr. Coconut Palm]

I used some red lava rock that is about 1" to 1.5" size as a mulch around the base of my Green Malayan Dwarf Coconut Palm that I planted in my yard on the east side of Corpus Christi in October of last year, and apparently it helped my palm make it through one of the worst winters in 20 years. I think it was a combination of the lava rock, compost added to the sandy soil, organic fertlizer, not watering too much during the chilly winter, and wrapping my palm with a blanket on the 5 coldest nights (lowest I got down to was 33.6F, but we had many more nights in the 30's and low 40's than normal) that got it through the winter, but I think it sure helps, and as it breaks down over time with watering, rain, and wind, I think it must add some vital nutrients to the soil. Just look at how the palms and other tropical plants thrive in the volcanic soil of Hawaii!

John

[SailorBold]

Enormous amount of heat.... especially in summer. I live in a much colder climate than you do though... My soil temp is in the 90's.... however the soil stayed very warm during the winter time... some latent heat from summer and some retained heat with winter sun.... so a combination of factors. I am still learning about it.

Here are a couple of pics...

Edited July 27, 2014 by SailorBold

[Mauna Kea Cloudforest]

I mulch with lava rock all over the place, keeps the water bill down and helps with keeping things from rotting in the Winter. I have not had any palms complain about the lava rock by not growing or dying. In fact, I think it improves the soil mineral content over time.

[Hammer]

I love the look and would use black lava in most of my beds, except...

I have city owned Eucs and Bouganvillia that drop litter EVERYWHERE on my property. The litter shows up against the lava and is difficult to clean out of the many cracks and crevices.

More importantly, in order to put down compost and other organic mulches and materials I would have to remove all the lava and then mulch and then replace the rocks. Waaaaayyyy too much work. So I have opted to mulch with more traditional options.

[SailorBold]

Interesting... While I use a crusherfine... (there are several volcanoes in the Albuquerque area) I don't know if it is available in other parts of the country or world for that matter... if local stone places carry it readily...?

In my situation- since it is a crusherfine- nothing gets stuck easily..its fairly solid that a lawn rake wouldn't disturb the surface too much. I will say this... it will fry fallen flowers and leaves black like charcoal. I have a desert willow that readily drops its spent flowers... and once in awhile a cottonwood leaf from a neighbors tree will land on it.. and it turns from green to black within a day. I was wondering where all of the flowers were going until I looked closer and they were fried carbon chips under the green canopy of the shrub. The living plants seem unaffected by it.. other than really fast growth.... and my desert willow budding out 6 weeks earlier than others in town.

[mike in kurtistown]

Here in rainy east Hawaii Island, we have lots of red and black cinder, which are just crushed lava rock. People in hard rocky areas use black cinder amended with some organic soil to grow things (Pauleen Sullivan's old garden in Kapoho) and most palms seem to really like it. But red cinder is avoided, I believe because it contains a lot of iron and too much iron is good only for serpentine-loving species. Red cinder is used for driveways and pathways, where it looks great and suppresses weed growth.

[SailorBold]

Oh... yes I will add it is a basalt crusherfine... and haven't had more than a handful of weeds. It is heavier and not as porous as some red pumice-like lava.

I'm assuming from somewhere around here where they are clearing areas for subdivisions.

[Hammer]

Sooooo freaking jealous of all that great looking rock just sitting there.

[Mauna Kea Cloudforest]

Here in rainy east Hawaii Island, we have lots of red and black cinder, which are just crushed lava rock. People in hard rocky areas use black cinder amended with some organic soil to grow things (Pauleen Sullivan's old garden in Kapoho) and most palms seem to really like it. But red cinder is avoided, I believe because it contains a lot of iron and too much iron is good only for serpentine-loving species. Red cinder is used for driveways and pathways, where it looks great and suppresses weed growth.

Really? Yikes, I use the red stuff all over, so far I've not had any issues, but I wonder which species are not serpentine soil lovers? So far, most of the Newcal stuff and the Madagascar palms seem to thrive with this stuff. I use the small gravel in my potting soil to aerate it. Brahea grow like weeds in it.

[Duppy]

I can't speak for any mineral benefits. To me, lava rock is the wall paper of the landscape world. It looks nice, until it's time to go back and redo or change things. One little rock will stop a shovel like concrete. Plus I like to walk barefoot in the yard. Stepping on a stray lava rock is so awesome. Just my 2 cents, and probably not even worth that.

v/r

Duppy

Edited July 28, 2014 by Duppy

[Jeff Searle]

I used two different colors of lava rock on a raised bed in the back yard. The only drawback would be messy trees in the area that would drop a lot of leaves on top of it and ruin the look. Other than that, I love the look of my bed and it has absolutely no negative drawbacks to using it.

[edbrown_III]

I started using the pink granite over 3 layers of 20 year weedcloth(over kill but I dont ever want to weed again or let this thing get out of control) in the front yard for the blue side of the yard. Its a big investment several times the red lava rock but when it rains with the blue braheas and copernecia and Seronoa it looks so good and really looks good the few blue encephalartos have really started picking up --- may be its leaching some thing down as granite sort of weathers its a work in progress so I have only completed about 3/4's of the bed. I also started incorparating granite as some of the inert matrix of the cycad soil /

Best regards

Ed

[mike in kurtistown]

I notice that there is rapid weed and grass growth in my areas covered with red cinder.

Never mind.

[JT in Japan]

I started using the pink granite over 3 layers of 20 year weedcloth(over kill but I dont ever want to weed again or let this thing get out of control) in the front yard for the blue side of the yard.

I like the idea of weedcloth underneath, Ed, but I'm guessing you've got a pretty "fixed" garden at this point, by which I mean you're not doing much planting anymore. To put in a new plant must be a real bear! I'm just starting a new front yard, so I'll be putting things in for the next year. Still not sure when to put the rock down...

[edbrown_III]

Not in this spot at least ---- I just turned 60 --- I dont want to weed this again (because I let it go to weeds ) I am hoping it buys me 25 years but I gotta still spot weed and this I can do ---- its just they get ahead of me . Tthe double and triple weed fabric and inert granite buys you some time that you can keep clean realatively easy in full sun and one layer of it in the woods (without cover) buys you atleast a year or so between spot weeding.

I got a few other weed mats down in places though out the my rain forest that I am gradually securing from weeds --- and Iam debating what to cover them with red lava is pretty cheap here than black granite then pink granite ---- I might just use the black granite to atleast provide stuff that Fl just dont have in its soils .

This is the heavy duty stuff I tried the cheap stuff a few years back with mulch and this was a mistake ---- it worked good for a while but the mulch decomposes and if you let any weeds build up ( whch they do) then you got a mixture of wild turf and cheap fabric and mulch. --- I scraped it down and put the 2 layers initially and gradually conquered the entire bed in 4 foot swathes of weed fabric. More front end work but I will know for sure 10 years from now it it was the right thing to do.

Best regards

Ed

[_Keith]

If it were available at a good price, I'd mulch with it here. Of course in my locale it would do squat for the weeds, but I do believe in the mineral leaching value of it.

[edbrown_III]

Keith,

yur right it wouldnt do squat for weeds without the real dense weed fabric --- claims 20 years but I put it down in 2 and 3 layers --- the rock is pretty inert relative ot the differnt mulches and you dont have the weeds putting down the roots and catching hold of the matrix that the gravel or mulch provides . this further reduces weeeds --- no igneous sources of rock in Florida so you have a land scape that doesnt need it but when you bring in the exotics (which I love) you got some supply of additional micronutrients . IMO

Best regards

Ed

[Mauna Kea Cloudforest]

The lava rock provides zero weed barrier effect. After all, a ton of stuff grows in that stuff in Hawaii. The rock is light and aerated and thus leaves enough room for weeds to germinate and grow. However, I also use some denser black lava rock that does act a little as a weed barrier.

[Mauna Kea Cloudforest]

Here is a picture of my brahea grotto. The contrast of the palms with the rock is fabulous, especially when the rock is wet.

[JT in Japan]

Here is a picture of my brahea grotto. The contrast of the palms with the rock is fabulous, especially when the rock is wet.

That's the look I'm looking for!

[Mauna Kea Cloudforest]

Arigatou gozaimashita, John. If I can offer more advice, I would recommend using both the little round lava rocks and use big chunks of lava to complement them. It also gives it more of that Hawaiian look which I like. Not sure if you can spot the bigger lava boulders in the picture.

[Palm crazy]

Axel that looks great in your garden. Here in the PNW small red laval rocks look horrible and will become weed infested in no time even with weed block.

You can actually fine Free! Small red lava rocks on C.L. around here, LOL! Looks very good in a dry climate though. Another rock that looks terrible here is white rocks, in a few years they turn green so people just don’t do it here.

Edited July 31, 2014 by Palm crazy