Using lava rock and lime rock

[Mauna Kea Cloudforest]

I've seen how palms just seem to thrive growing on pure lava rock on the big Island. There's no ground water there, just lots of porous lava rock, and obviously palms grow very well on this type of substrate. So I am surprised I've never heard of anyone using much lava rock when preparing planting beds for palms on the mainland.

Tomorrow, I am getting a nice delivery of some pretty good chunks of lava rock, large up to two feet wide, all the way to some 1/4" size that I plan on mixing into the soil.

I am taking a similar approach with lime stone. I'm getting a ton delivered to create a nice growing bed for my brahea, all of which supposedly love limestone.

Why isn't anyone trying this out? Seems it would do wonders for a lot of palms. I suspect the lava is part of why much of Floribunda's palms simply thrive when i plant them here no matter what time of the year it is. They show up already growing in lava rock.

[MattyB]

Don't you already have exceedingly well draining soil? Weren't you having problems with things drying out? I'm just wondering why the lava. I'd be bringing in clay if I were you.

[Mauna Kea Cloudforest]

Don't you already have exceedingly well draining soil? Weren't you having problems with things drying out? I'm just wondering why the lava. I'd be bringing in clay if I were you.

Most of the lava is for landscaping purposes. I use mostly sonoma rock but I am mixing it up with some lava rock. The smaller stuff is used as mulch and as nutrient enhancements.

[daxin]

Big Island has those convenient daily rain and high relative humidity to make it all work. Lots of oxygen in the roots but never dry. It's like bonsai with unlimited root run. The only caveat is that nutrients can get leached out very quickly. I wish we could magically switch between lava rock in winter and clay in summer here in California.

[LJG]

Alex, while I don't see the value in doing lava with plants in the ground. I do however use lava rock shipped in from Hawaii from a guy on eBay for some of my potted palms. I too noticed that some palms in Jeff's mix would do fine for me and once moved to other mixes would suffer or die. Particularly with the NewCals. Having moved to 33% lava rock in my mix I have changed this. Most likely only anecdotal, but that works for me.

The lime rock has been discussed before and I mentioned in my planting holes where my Cuban stuff goes I always add wetted cement mix and broke it up into chunks after it dries. I put a bunch of these in the planting hole. I have witnessed the success of this as myself and 3 other people all planted a large Copernicia fallaensis at the same time back in 2008. One is dead, the other two are half the size of mine. I know there are many factors that could effect the outcome but I really believe the lime rock played a key role in the growth of mine.

Another thing to point out is that when I transplanted a cuban palm that I planted in to much shade, while digging it out I found that the roots literally were encasing the lime rock I put in the holes years earlier. I doubt it was coincidence.

[Kim]

When planting palms in my previous San Diego garden, I started doing what I called "volcano planting". Some of the soil in my garden was like sandstone, and some was like river silt. In the hard soil areas I would dig a large hole then fill it partially with alternate layers of lava rock and palm/cactus mix, place the rootball on top, and continue in the same manner, then topping off with a thick layer of black lava rock with the idea of holding heat from the sun. I did this with some of the larger pots of Hyophorbe verschaffeltii, Rhopalostylis sapida, and some small Archontophoenix purpurea and Coccothrinax fragrans. In the softer soil areas, palms went into amended soil. As long as I had the garden, most of the palms thrived, whether in the rock planting or the softer soil, but I will say I dumped a heck of a lot of water into those rock areas. The one species that didn't fare well in the lava rock was the A. purpurea. There were 3 small 1-gal. palms planted as closely as possible; 2 died, 1 survived and was growing very slowly. Everything looked really healthy last time I visited, but I can't state with any certainty that the lava rock method was a true positive or not.

As you know, in Hawaii the lava affords perfect drainage. That said, there is mud in with the rock which never really dries out. The rains are so frequent and high humidity prevents things from drying out. For example, you can break off a piece of coleus, lay it on a rock, and it won't wilt for about 3 days. That is due to the ambient humidity. You know that dense, moist, warm air that hits you the moment you get off the plane in Hawaii? That, I believe is the true secret to growing healthy palms, and it's impossible to re-create that outdoors in California.

[Mauna Kea Cloudforest]

You know that dense, moist, warm air that hits you the moment you get off the plane in Hawaii? That, I believe is the true secret to growing healthy palms, and it's impossible to re-create that outdoors in California.

Oh yes, that amazing warm and humid Hawaiian air, it feels so good after three months of Northern California Winter. Coastal California has some of that, but not all year 'round.

[richnorm]

Scoria (lava) grit is very cheap here. I have seen plants grown in pure scoria grit but here it is wet and humid. I use it myself to aid drainage and provide (in my mind at least) a slow supply of minerals. I too sometimes add it to my potting mix.

[MKIVRYAN]

I'm mixing in lava rock in with all my plantings but I have heavy clay and need the drainage. I get 1/4 minus local. They carry red and black. So far I see no difference in how well they work

[stevethegator]

Starting somewhere in Broward South Florida "soil" becomes straight, exposed limestone. Most gardens in Maimi and the Keys have to deal with this as planting medium. There is groundwater and palms that can tolerate the alkalinity love it, but it's hard to fertilize and for the more exotic stuff you have to chip out a wide hole and backfill with good black dirt.

[ghar41]

On the subject of rock, I have been in conversations with others about the use of decomposing granite as a top substrate for growing palms and cycads in alkaline soils in California. Apparently it is acidic by nature and it has some minerals available to plants. It also holds no moisture, unlike organic mulch, but it helps maintain a relatively stable moisture level in the soil beneath when used as a top dressing. With water restrictions becoming what they are, this sounds like an excellent option for my garden. Also, These are really good characteristics for palms and cycads that are sensitive to too much moisture against their trunks like Parajubaeas in hot climates. David Sylvia uses it in San Jose and his amazing garden seems to never have a spot on it.

[sashaeffer]

I can add that I bought 3 small palms from Exotic Palms (Steve Stern) and noticed that all three had crushed black lava rock in the soil as they were all shipped in their grow pots. One, the Joey palm had only black lava rock for it's "soil" I guess in part for it's sensitive roots, drainage and helps with humidity.

I did find this interesting video from a amateur plant hobbyist that did a side by side study using Black lava rock only as a top dressing.

http://www.foodforesters.com/showthread.php?t=83

[Mauna Kea Cloudforest]

I've seen that thread, it's bogus. 3 weeks is too short to see a nutritional benefit. The results this guy is seeing are due to the lava rock holding in moisture. I use that approach with my potted palms, and it really works. But it could be gravel or decomposed granite, the effect would be the same.

[KennyRE317]

When planting palms in my previous San Diego garden, I started doing what I called "volcano planting". Some of the soil in my garden was like sandstone, and some was like river silt. In the hard soil areas I would dig a large hole then fill it partially with alternate layers of lava rock and palm/cactus mix, place the rootball on top, and continue in the same manner, then topping off with a thick layer of black lava rock with the idea of holding heat from the sun. I did this with some of the larger pots of Hyophorbe verschaffeltii, Rhopalostylis sapida, and some small Archontophoenix purpurea and Coccothrinax fragrans. In the softer soil areas, palms went into amended soil. As long as I had the garden, most of the palms thrived, whether in the rock planting or the softer soil, but I will say I dumped a heck of a lot of water into those rock areas. The one species that didn't fare well in the lava rock was the A. purpurea. There were 3 small 1-gal. palms planted as closely as possible; 2 died, 1 survived and was growing very slowly. Everything looked really healthy last time I visited, but I can't state with any certainty that the lava rock method was a true positive or not.

As you know, in Hawaii the lava affords perfect drainage. That said, there is mud in with the rock which never really dries out. The rains are so frequent and high humidity prevents things from drying out. For example, you can break off a piece of coleus, lay it on a rock, and it won't wilt for about 3 days. That is due to the ambient humidity. You know that dense, moist, warm air that hits you the moment you get off the plane in Hawaii? That, I believe is the true secret to growing healthy palms, and it's impossible to re-create that outdoors in California.

I think that that's exactly what the in ground lava rock does that makes the biggest difference. To whether or not lava rock provides any nutrients I have no clue but i do know that they'll hold heat which the roots love.

[SailorBold]

If there is moisture.. especially with frequent watering.. it will break down. I read some defining information on Wikipedia for Rockdust and it is interesting.

I would post it or some of the information here- I cant figure it out.

They don't classify it as a fertilizer.. but from some analysis they have on there it looks like it has quite a few micros.

Good topic for discussion.

[SailorBold]

I just had a thought to add... Rainfall is fairly acidic correct? I assume that would break it down faster from a chemical perspective. There is a good amount of sulfur also so bio stuff would be into play. Perhaps areas with higher rainfall creates a better balance for plants.

I'm not currently monitoring my soil for nutrients so I will be able to add observational information as time goes by.

My soil is alkaline and my tap is alkalinish.. I checked rainwater pH once and it was something in the 4 range... I did this after a quest to figure out why my Ocotillo repeatedly leafed out ONLY after rainfall and not with my tap water. That's the only thing I came up with.

[Mauna Kea Cloudforest]

FYI, a pH of 4 is wicked acid, not alkaline.

Here's my 2 cents on rocks and palms. Palms are distinct from other plants in that they have a much higher demand for minerals and therefore lava rock or any other rocks for that matter are no brainer soil enhancers. There is no doubt that lava rock gravel will provide micronutrients over longer periods of time. The piece that I challenge is that you will not see any micronutrient driven results from rock in gravel form in just 3 weeks, let alone three months. If you apply the rock in dust form, you will see results much faster, but healthy soil mineralization should be a gradual process; it's easy to do harm to the plants if the soil is overloaded with rock dust, because the dust will throw off pH and other parameters.

[SailorBold]

I agree. As far as cultural requirements for palms; opposing desert plants... my goal is to target the nutrient availability and gain understanding in further depths regarding definitive root structures and a plants ability to obtain these nutrients outside their environmental ranges.

I have basalt crusherfine.. as you know. There is a fair amount of dust in it but the majority of the crushed rock fragments are small in nature. I also live in an area of low rainfall and sandy soil outside of an alluvial decomposing granitic fan. I didn't mix the material into the soil so whatever these palms recover will be dissolved by either rainfall and/or alkaline tap water.... just to split a hare further.

I have some extra material.. and I plan on getting more locally. I don't know how scientific you are but perhaps you would like to experiment further... with actual rock dust..? I love doing stuff like that. I only assume that you have access to lava rock only from what I see in your awesome garden.

If it fits.. it ships.

[SailorBold]

I'm a chemist just FYI

hydronium is a pickle.

Edited September 11, 2014 by SailorBold

[Mauna Kea Cloudforest]

I'm a chemist just FYI

hydronium is a pickle.

So as a chemist, you surely know that [H₃O⁺] = 10^−pH and if pH = 4 you've got something ultra-acidic.

Unless, of course, you're one of those special Albuquerque chemists...

[SailorBold]

Lol...that show is loosely based on reasons why people don't plant palm trees here.

Indeed your math looks correct however nutrient uptake is what I am after.

Balance the water of life and that will most likely solve it.

How is your stoichiometry?

[Hammer]

I wish we could magically switch between lava rock in winter and clay in summer here in California.

I'll drink to that.

[sashaeffer]

My non scientific experiment. No videos, just stills.

Two Purple King palms seedlings that I bought from hobbyist while on California trip this spring. Assuming they germinated at the same time as they are the same size. I only put Black Lava rock pebbles in on top of one naturally and I chose the one that is just a tad bit smaller although it has a new spear pushing and the other one doesn't.

[SailorBold]

sashaeffer- perhaps you should mulch the other palm to prevent moisture loss mentioned earlier. Cool.

I'm going to try something similar... Ill keep this thread posted... Im still throwing ideas around until I finalize it and choose palm species.

There are several articles of information on the internet praising the benefit of mixing rock dust into deficient soils...

Additionally, you have a greater surface area with your pebble size.

[sashaeffer]

Had to order online. I have some of my potted palms mulched with small wood chips...and it does work great keeping moisture in BUT my dogs also love the mulch and pull it out of the easy to get to pots and chew on it throughout the house, so I have to sprinkle cayenne pepper on the mulch which does seem to help. These two Purple Kings sit right on the floor and would be easy pickings for the mulch. I just hope they don't like lava pebbles just as much.

[Mauna Kea Cloudforest]

Don't you already have exceedingly well draining soil? Weren't you having problems with things drying out? I'm just wondering why the lava. I'd be bringing in clay if I were you.

Matty, here's the technique I've been using. My native soil, when undisturbed, takes about 10-20 minutes to drain a 15-20 gallon hole. What I do is I fill in half way native soil on the sides and half with a porous medium that can hold water and let it drain into the rootball. If you look at the diagram below, you will see the approach I use. Drippers (typically 2-4 x 1GPH) on rootball, and manual supplemental watering in the "swale" made of porous material. This system is dynamite! However, if you look at the second picture, you can see what a mole tunnel does to the whole system. It destroys it!

[Ben in Norcal]

Sorry to press the issue, Axel, but what is wrong with 15-20 minutes to drain? That seems adequately fast draining, and might permit the root ball more time to get some moisture. You are far more skilled and experienced than me at this stuff, but given what I saw on your slope last weekend - I would be trying to slow drainage down as much as possible.

[sashaeffer]

Whats the deal with Moles and Palms when in the ground? I've seen lots of posts about Moles destroying palms. Why are they attracted to palms? I have some palms in the ground...and a few moles in the yard but they don't seem to care about plants/palms.

[Ben in Norcal]

You probably aren't having the drought California is. I believe they are attracted to Axel's drippers around palms by the worms that tend to be there. I suspect in a regular year they would be more distributed and not pulled into the very focused damp areas around palms. That's my hypothesis, anyway.

[sashaeffer]

Makes sense. I thought there was something about Palms that Moles went after. Here in Nebraska they just eat Grubs in the lawn and do their damage to the grass and not plants.

[Mauna Kea Cloudforest]

Sorry to press the issue, Axel, but what is wrong with 15-20 minutes to drain? That seems adequately fast draining, and might permit the root ball more time to get some moisture. You are far more skilled and experienced than me at this stuff, but given what I saw on your slope last weekend - I would be trying to slow drainage down as much as possible.

The drainage is fine, as long as moles don't burrow. Once there is a burrow, drainage is instantaneous. That's what makes it problematic.

[Alicehunter2000]

You probably aren't having the drought California is. I believe they are attracted to Axel's drippers around palms by the worms that tend to be there. I suspect in a regular year they would be more distributed and not pulled into the very focused damp areas around palms. That's my hypothesis, anyway.

That's the best theory I've ever heard on the subject.

You all consider 22-30 minutes fast draining? .....lol ....... I need to make a video to show ya'll what the definition of fast draining is.....would take less than a minute.

I like the idea of using crushed material for long term slow micro nutrient release .....what rock would have the best combo of things like Mn and Mg ....... Dang .... where are all the geologist? ... must be over in a meteorology thread.

[Mauna Kea Cloudforest]

Ben is right, that is also exactly what my gopher guy said. The moles are having a real tough time with the drought. My garden is like an oasis in a desert. Pretty much the entire neighborhood doesn't give a rats about their gardens so no one is watering anything. My neighbor's landscaping is dying, and all the moles are heading to my place.

David, I get your kind of drainage when the moles have sprung into action. But at least you guys get continuous rainfall during the Summer so who care how fast it drains. The faster the better, like on the Hawaiian lava.

[_Keith]

You all consider 22-30 minutes fast draining? .....lol ....... I need to make a video to show ya'll what the definition of fast draining is.....would take less than a minute.

Opposite here. When the rains come day after day sometimes the water table gets so high that if you dig a hole it backfills itself with water to within an inch or two of the soil line.

[SailorBold]

Interesting Keith.. Rainfall or lack of... is another important factor (or variable) added to the complexity of palm fertilization.

[Mauna Kea Cloudforest]

Here's the lava bed for part of my brahea collection.

[MattyB]

So, have you trapped any moles yet?

[Hammer]

Here's the lava bed for part of my brahea collection.

Looks great. Gonna look amazing once those puppies get a few feet of trunk.

[SailorBold]

Wow! That put some color on the ground. It's hard to see the slope angle but I suspect with your planting technique and the addition of those boulders that will help enormously with water retention.

Looks very nice with the blue leaves of that armata!

[sashaeffer]

My non scientific experiment. No videos, just stills.

Two Purple King palms seedlings that I bought from hobbyist while on California trip this spring. Assuming they germinated at the same time as they are the same size. I only put Black Lava rock pebbles in on top of one naturally and I chose the one that is just a tad bit smaller although it has a new spear pushing and the other one doesn't.

Update since Sept. 14

So far height is exactly the same, but condition of them is much different, although the non lava rock king does have nice spear pushing and the other one doesn't but was last to do so. Lave rock king plant in general looks much healthier with no brown tips at all while other one has them on all ends of fronds. Both sit in bright, indirect light, get watered every two weeks with RO water. Grow much slower than all the other species of King palms that I have inside, but normal for this species from what I've read.

Same height.

Lava rock palm.

Edited March 1, 2015 by sashaeffer