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Mulch or Rocks?

26 posts in this topic

I've been wondering if spreading river rocks around a tree will act just as effectively as mulch to hold soil moisture? Normally I lay a thick layer of mulch about each palm before summer but just use rocks during winter [to provide more warmth]. Are rocks just as useful as mulch in maintaining moisture levels in the soil?

Here's a photo of river rocks around a hyophobe verschaffetii. I will add more rocks if it works as well as mulch.

010.jpg

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Not really, Happ. Wood mulch serves better as a soil moisture enhancer/retainer.

Rocks get a lot hotter than does mulch and conversely, tend to dry the soil out faster than does a tree planted with organic mulch materials surrounding the root ball. Rocks, too, certainly cannot hold water as can wood mulch, for example.

I still utilize rocks because they are very decorative and do make weeding a very easy job, but in my opinion, wood mulch would be better for you as a moisture retaining material (especially in a low rainfall area like So Cal.)

Another option is an under layer (not underwear) of cypress/eucalypt (about 1 1/2 inch) mulch as a moisture regulator, and then about a two inch layer of polished river styones over the mulch.

Looks great; serves two purposes.

Just food for thought so to speak!

Pablo

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Makes sense, thanks Paul. :)

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Thanks, Happ!

OI wouldn't give up my river rock, though. Texture is so very much a part of interesting garden design. There's definitely places for all kinds of contrasting materials especially when one uses a limited variety of plant material.

An Alexander palm DOES look quite different with: grass, mulch, or rock under its drip line. I'll use all of the above, and visitors get very different vibes from all three types of soil-covered beds materials.

That was a good question, though, Happ!

Pablo

PS: Do you think that you'll be on the right coast this spring-summer?? Let me know if you are planning to, OK?

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Thanks, Happ!

OI wouldn't give up my river rock, though. Texture is so very much a part of interesting garden design. There's definitely places for all kinds of contrasting materials especially when one uses a limited variety of plant material.

An Alexander palm DOES look quite different with: grass, mulch, or rock under its drip line. I'll use all of the above, and visitors get very different vibes from all three types of soil-covered beds materials.

That was a good question, though, Happ!

Pablo

PS: Do you think that you'll be on the right coast this spring-summer?? Let me know if you are planning to, OK?

Thanks for the inquiry, Paul but I canceled my trip to Miami this year [saving $ :unsure: Are royal poinciana beginning to flower? How about showing us some photos of your wonderful gardens in Florida & Panama? :mrlooney:

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Paul

. . . .said it all . . . .

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Thanks, Happ!

OI wouldn't give up my river rock, though. Texture is so very much a part of interesting garden design. There's definitely places for all kinds of contrasting materials especially when one uses a limited variety of plant material.

An Alexander palm DOES look quite different with: grass, mulch, or rock under its drip line. I'll use all of the above, and visitors get very different vibes from all three types of soil-covered beds materials.

That was a good question, though, Happ!

Pablo

PS: Do you think that you'll be on the right coast this spring-summer?? Let me know if you are planning to, OK?

Thanks for the inquiry, Paul but I canceled my trip to Miami this year [saving $ :unsure: Are royal poinciana beginning to flower? How about showing us some photos of your wonderful gardens in Florida & Panama? :mrlooney:

I will take photos of local Poincianas, Happ when they commence their beautiful (& pretty long) show!!!.

They're about a month away from bloom; still shedding leaves and old seed pods.

Panama? I can't go til I am thoroughly healed and it's not happening as rapidly as I thought it would, Happ! Pisses me off!

I don't have much choice; I just have to wait, It's going on seven months (on the 22nd.) since the big rig nailed my X-Terra. Dizziness, numbness of the extremities & headaches are still a part of my daily life! Pretty lousy, my friend. Pretty lousy!

Late.

Paul

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

I read several studies about mulch using up nutrients near the surface, particularly things like sawdust, but that it was mostly nitrogen robbing and easily compensated for with normal fertilizer. There have even been a few articles challenging that too, saying that nutrient robbing was not an issue. I started mulching this year, but I also started using fertilizer spikes as well, thinking that if there is a problem the nature of spikes would be perfect to overcome it.

I'll let you know come fall what the results are.

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

Ken,

surely a lot of tropical rainforest soils are pure mulch...decayed leaves and wood over often heavily leached subsoil?

So you could argue that the reverse is true in some cases and that mulch/micro organisms/mychorrizal fungi are feeding the palms in situations where there are limited nutrients otherwise available.

I know that in my impoverished dune sand, no mulch = no growth. I usually scrape back the top layer of mulch and apply fertilizer to the decomposing layer underneath, then replace or add more over. I've found that way the nutrients don't get washed out through the sand when I irrigate. My soil is dead except around mulched trees!

Cheers,

Jonathan

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

Hi Ken:

One is supposed to keep the mulch (of any kind) a couple of inches away from palms' trunks to reduce entry probabilities of fungi, and insects, in Florida and the humid SE Coast. I'm not quite as sure that a worse detriment to our palms in planting to deeply, in any part of the country! I always have about two-three inches of my palm root balls sit above the surrounding area of ground. the extra aeration assists in keeping the roots healthier.

As far as what to do in an arid part of the U.S, like So Cal, I think that mulch up to the trunk shouldn't pose too much of a problem. It would be a greater problem, Ken, I feel if the mulch layer is too thick (more than two inches), and this material "mats down" into a semi-impenetrable exphyxiating layer of wood mulch.

I've dealt often with that condition, and the first thing I do is break up that mass of what appears to be almost like particle board! Those roots need water...but they even need air just as much, for the palms' well-being.

Luego.

Pablo

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

Ken,

surely a lot of tropical rain forest soils are pure mulch...decayed leaves and wood over often heavily leached subsoil?

So you could argue that the reverse is true in some cases and that mulch/micro organisms/mychorrizal fungi are feeding the palms in situations where there are limited nutrients otherwise available.

I know that in my impoverished dune sand, no mulch = no growth. I usually scrape back the top layer of mulch and apply fertilizer to the decomposing layer underneath, then replace or add more over. I've found that way the nutrients don't get washed out through the sand when I irrigate. My soil is dead except around mulched trees!

Cheers,

Jonathan

For sure what you say about rainforests is true.

I have no real soil on my farm. Only broken limestone, water and fertilizer. The fertilizers are time release and do not get rapidly leached. I use no mulch. It is a nest for insects and damaging microbes. BTW fertlizer kills all mychorrizal fungi.

I have seen gardens (in our completely devoid of nutrients) Florida soils where very little fertilizer is used and there is heavy mulch. The palms in those gardens look half as good as the ones with high fertilizer maintenance and the research by the University of Florida shows why.

Can you see my "soil" in this picture?

post-50-1240275243_thumb.jpg

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Makes perfect sense to me, Jonathan!

Paul

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Thanks, Happ!

I wouldn't give up my river rock, though. Texture is so very much a part of interesting garden design. There's definitely places for all kinds of contrasting materials especially when one uses a limited variety of plant material.

An Alexander palm DOES look quite different with: grass, mulch, or rock under its drip line. I'll use all of the above, and visitors get very different vibes from all three types of soil-covered beds materials.

That was a good question, though, Happ!

Pablo

PS: Do you think that you'll be on the right coast this spring-summer?? Let me know if you are planning to, OK?

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

Ken,

surely a lot of tropical rain forest soils are pure mulch...decayed leaves and wood over often heavily leached subsoil?

So you could argue that the reverse is true in some cases and that mulch/micro organisms/mychorrizal fungi are feeding the palms in situations where there are limited nutrients otherwise available.

I know that in my impoverished dune sand, no mulch = no growth. I usually scrape back the top layer of mulch and apply fertilizer to the decomposing layer underneath, then replace or add more over. I've found that way the nutrients don't get washed out through the sand when I irrigate. My soil is dead except around mulched trees!

Cheers,

Jonathan

For sure what you say about rainforests is true.

I have no real soil on my farm. Only broken limestone, water and fertilizer. The fertilizers are time release and do not get rapidly leached. I use no mulch. It is a nest for insects and damaging microbes. BTW fertlizer kills all mychorrizal fungi.

I have seen gardens (in our completely devoid of nutrients) Florida soils where very little fertilizer is used and there is heavy mulch. The palms in those gardens look half as good as the ones with high fertilizer maintenance and the research by the University of Florida shows why.

Can you see my "soil" in this picture?

Ken,

I should qualify my statement by saying I only use organic fertilizers....so you are probably right about a high ferts program. As much as anything my soil is just too damn thirsty to not mulch it. No town water supply here, unfortunately....

Insect and microbial pests are probably more of an issue for you with your heat and humidity than for me with my cool dry climate. Horses for courses - its always interesting to hear what works for others.

Could you post a link to that University of Florida study? - it sounds intriguing.

Cheers,

Jonathan

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My experiences in the desert are exactly the opposite from pauls. I dont use river rock at the base of palms, though I do have some river rock as a landscape feature, its beautiful. I use crushed +3/4" mesh granite, about 3-4" thick and the bottom layer is quite cool and wet. The rock on the bottom doesnt heat up at all with the hottest sun of the summer, @ 115F. Part of the reason is the air space between rocks prevents the heat transfer from the surface down to the soil level. I dont think that would be the same with larger river rock, which would conduct heat more effectively to the soil level as there are no air gaps. With granite rock, the top rock is quite hot, cant walk on it without pain, but 3" under its cool and damp. Rock prevents evaporation as it CANNOT absorb water, water cannot pass through it to evaporate like it can through mulch, and the surface area of rock would be much lower for evaporation. I tried mulch alone in the beginning and it dried out so fast in the desert, it was pretty much worthless, my palms had a dried look to them. Since laying down that rock, the palms have improved greatly in their vitality. To think I went more than 1 year defying the common knowedge here, a real smart Ph.D. :lol: .

Now, I use this rock on ammended clay soils that include some compost mulch in the top 3" of soil, I suspect sandy soils might not work so well with rock as there is no component to hold moisture then, the water will just drain down. I think you look at it two ways, first to hold water (clay or mulch), second to prevent evaporation (rock or mulch). Rock prevents evaporation much better than mulch in a dry climate, but if you have sandy soils, rock doesnt hold any water for you and you lose water by fast drainage. Certainly granite rock is the most common ground covering in the desert and we have been focused for decades on using various methods to conserve water here. Mulch has the additional decomposition nutrients that rock cannot supply, but humic acid sure can.

As you can tell paul is worried about water draining away in his sandy FLA soil, while and I am worried about water losses due to evaporationin my dry climate. I suspect taht rock could work well in california, especially inland with its dry/hot summers.

Edited by sonoranfans
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I love rocks - but definitely I notice the soil retains moisture alot longer with the wood mulch.

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Are you all sure mulch is so good for palms? Anyone know about the research that shows microbes in mulch use up minnor elements before the palm can get them?

As far as water and heat are there any studies or are we just going by a hunch?

Ken,

surely a lot of tropical rain forest soils are pure mulch...decayed leaves and wood over often heavily leached subsoil?

So you could argue that the reverse is true in some cases and that mulch/micro organisms/mychorrizal fungi are feeding the palms in situations where there are limited nutrients otherwise available.

I know that in my impoverished dune sand, no mulch = no growth. I usually scrape back the top layer of mulch and apply fertilizer to the decomposing layer underneath, then replace or add more over. I've found that way the nutrients don't get washed out through the sand when I irrigate. My soil is dead except around mulched trees!

Cheers,

Jonathan

For sure what you say about rainforests is true.

I have no real soil on my farm. Only broken limestone, water and fertilizer. The fertilizers are time release and do not get rapidly leached. I use no mulch. It is a nest for insects and damaging microbes. BTW fertlizer kills all mychorrizal fungi.

I have seen gardens (in our completely devoid of nutrients) Florida soils where very little fertilizer is used and there is heavy mulch. The palms in those gardens look half as good as the ones with high fertilizer maintenance and the research by the University of Florida shows why.

Can you see my "soil" in this picture?

Ken, Do you have the link to the USF study? I've suspected my problem is the use of too much mulch!

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Don't the palms or plants in a particular garden determine the best type of soil and top dressing used? When you look at where the palms grow in habitat, which should be the optimal conditions for them, I would think that would dictate the answer to using mulch, rocks or in my case sand and crushed shells. It seems that there are palms that like lots of moisture around their roots (the forest palms) and then those that like the fast draining capabilities of sand (many Caribbean and African palms). Here is one of my gardens that uses crushed shells as the to dressing and soil heavy in limestone and sand underneath that was brought in.

2568oir.jpg

2nvv786.jpg

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Don't the palms or plants in a particular garden determine the best type of soil and top dressing used? When you look at where the palms grow in habitat, which should be the optimal conditions for them, I would think that would dictate the answer to using mulch, rocks or in my case sand and crushed shells. It seems that there are palms that like lots of moisture around their roots (the forest palms) and then those that like the fast draining capabilities of sand (many Caribbean and African palms). Here is one of my gardens that uses crushed shells as the to dressing and soil heavy in limestone and sand underneath that was brought in.

2568oir.jpg

2nvv786.jpg

Whatever the benefits....I like that look! :mrlooney:

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Appreciate the feedback of climatic factors to be considered. I combine both mulch & rocks but no mulch during winter.

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I hate when rocks get messy with dirt and debris...it piles up in between the rocks and I eventually have to take them out a clean the whole thing. I still use them in places though, I like the look.

Overall, I use mulch more often. I like its eventual value as compost when it breaks down and can add thin layers on top, over time.

I suppliment with coffee grounds (free from Starbucks) and let the leaves in the Fall break down where they land. I only have to clean garbage out of it.

I am using fish emulsion almost exclusively now, and only use nutricote granular fertilizer for cycads.

Bugs are not so much a problem for me, with the exception of the argentine ant. I do understand why growers in more humid climates like Hawaii and Florida might shy away from it, where bugs are more of a problem.

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I hate when rocks get messy with dirt and debris...it piles up in between the rocks and I eventually have to take them out a clean the whole thing. I still use them in places though, I like the look.

Overall, I use mulch more often. I like its eventual value as compost when it breaks down and can add thin layers on top, over time.

I suppliment with coffee grounds (free from Starbucks) and let the leaves in the Fall break down where they land. I only have to clean garbage out of it.

Bugs are not so much a problem for me, with the exception of the argentine ant. I do understand why growers in more humid climates like Hawaii and Florida might shy away from it, where bugs are more of a problem.

Glenn

How do you deal with ants? I am seeing many nests lately.

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I hate when rocks get messy with dirt and debris...it piles up in between the rocks and I eventually have to take them out a clean the whole thing. I still use them in places though, I like the look.

Overall, I use mulch more often. I like its eventual value as compost when it breaks down and can add thin layers on top, over time.

I suppliment with coffee grounds (free from Starbucks) and let the leaves in the Fall break down where they land. I only have to clean garbage out of it.

Bugs are not so much a problem for me, with the exception of the argentine ant. I do understand why growers in more humid climates like Hawaii and Florida might shy away from it, where bugs are more of a problem.

Glenn

How do you deal with ants? I am seeing many nests lately.

Happ,

I floated this question on a post awhile back. The Terro baits (or the home made remedies using boric acid) have worked the best for me. Theyre effective in getting to the queens in the nests. Whatever you do, dont waste time on pesticides... it stimulates reproduction. They have multiple queens that even leave the nests and forage with the commoners. Damn good thing their bite is mild.

http://en.wikipedia.org/wiki/Argentine_ant

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I use mulch in my beds for weed control (I use rocks in walkways and really like the look). I hope to eventually have all ground cover and not need much mulch in the beds.

I thought retaining moisture for bedding plants is important since they have shallow roots. Does surface moisture really help established palms much?

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I use mulch in my beds for weed control (I use rocks in walkways and really like the look). I hope to eventually have all ground cover and not need much mulch in the beds.

I thought retaining moisture for bedding plants is important since they have shallow roots. Does surface moisture really help established palms much?

Although we are in-state neighbors, I don't know how similar you climate is to mine. Here it is feast or famine. We either have more than enough water or drought and seem to constantly vasilate between the two. A good layer of mulch seems to moderate between the two, but does fall victim sometimes to too much moisture.

I think a good ground cover might be better, sucking up excessive moisture and being an early indicator of drought. Shade ground covers provide several choices, but full sun ground covers seem to be a tougher find. I would be interested in knowing your opinions on these.

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