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Garden Built on Sand


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I knew that when my house was built the builder spread sand on top of the soil before turfing it over. What I hadn't realised until today was that the sand goes down over a foot (30 cm). I don't know much about gardening, but surely this can't be a good thing. Water won't be retained. There's no nutritional value in sand, and any chemical fertiliser I apply will just wash away. So, what can I do to fix it? Apply some sort of top dressing regularly? If so, what is suitable and readily available in Thailand? There don't appear to be any worms (no worm casts on the lawn). Is that going to be a problem?

Thanks.

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How is the lawn holding up in the dry weather?

If it's doing ok then change nothing, you certainly don't want to go digging everything up smile.png

How far below the surface does the growing medium extend before you get to the sand?

What sort of grass do you have, broad leafed Malay or the narrow leafed Japanese?

Some interesting stuff on top-dressing here http://www.lawn-care-academy.com/top-dressing-lawns.html compost or good topsoil (or a mixture) is the stuff to use.

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I did say " I don't know much about gardening"! Anyway, I'll do my best.

The lawn just doesn't hold up in dry weather. I have to water it every day for over an hour to keep it green. (It's roughly 200 sq. metres.)

There is no growing medium. The top foot (at least) of "soil" is plain sand. (I stopped digging down at this point.) The reason I discovered this is because I now want to add some plants. Digging the holes I just encountered sand, pure sand.

No idea what sort of grass I have. Actually, it's a mix of at least four or five types. One is broad leaves, growing flat in rosettes. (To be honest, I'm not even sure if it is a grass or not. Lawn weedkiller kills it off, but it grows back.) Others range from "normal" grass to rather coarse, fast growing stuff.

(I had read that if you mow the lawn regularly - and I mow once a week - the coarse grasses and weeds would die out. Not happening for me. Would prefer not to use weedkillers.)

Thanks for the link. I wonder whether the bags of "soil" they sell, which appear to be mostly vegetable matter scraped from some forest floor, would be OK. The particles aren't that fine, though.

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There are two ways you can solve your problem with the sand -

  • Build up the composition of your sand with the addition of fine clay particles or by the addition of organic matter such as compost. Do not add this in layers but mix it in as well as possible.
  • OR
  • The other alternative is to use plant material that will grow in sand or well drained soils - have a look at coastal vegetation for ideas. There are palms and casurinas ,that will do okay. Malay Grass will handle low fertility sandy soils quite well for turf . There are succulents for colour and plants like lavender (think Mediterranean style) that will adapt. Numerous other plants that will survive in sandy soils if you do a bit of research.
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While on this subject and not wishing to hijack it can anyone tell me please where I can purchase some lawn weedkiller/feed thumbsup.gif

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While on this subject and not wishing to hijack it can anyone tell me please where I can purchase some lawn weedkiller/feed thumbsup.gif

I don't think you can buy lawn weed killer in Thailand. I bring a couple of bottles of Weedol with me whenever I return back to the UK.

Thai Watsadu sells bags of 16:16:16 pelleted fertiliser which does the job. (Other places like Homepro, Boonthavorn don't seem to carry it.) I think the brand's called "Rabbit". 3 kg bags. There's at least one other mix, but my (limited) understanding is that 16:16:16 is OK for grass.

Incidentally, I strongly suspect that Weedol kills Malay grass. (I now think the broad leaved invasive weed in my "lawn" is Malay grass thanks to previous posters. It definitely dies off after I apply Weedol.)

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There are two ways you can solve your problem with the sand -

  • Build up the composition of your sand with the addition of fine clay particles or by the addition of organic matter such as compost. Do not add this in layers but mix it in as well as possible.
  • OR
  • The other alternative is to use plant material that will grow in sand or well drained soils - have a look at coastal vegetation for ideas. There are palms and casurinas ,that will do okay. Malay Grass will handle low fertility sandy soils quite well for turf . There are succulents for colour and plants like lavender (think Mediterranean style) that will adapt. Numerous other plants that will survive in sandy soils if you do a bit of research.

Sorry to go off topic, but how does one obtain organic matter?

I wouldn't dare have a compost heap here as it would be breeding heaven for snakes?

Relying on the 'right' plants is problematical - as it depends on sun/shade etc.

Additionally, how does one find fine clay particles? Another genuine question as I'd love to add some clay to the soil to retain water.

I bought a lavender plant once (only time I've seen it sold here) and it quickly died. Not sure whether it was not enough/too much water or too much sun.

The only shrubs that survive well in v dry soils are frangipani and bougainvillea in my experience.

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When you mow the lawn do you remove all the cuttings or leave them to 'mulch' back in ? Leave the cut grass to rot back in.

Every couple of weeks or so buy a few bags of soil from your local garden centre and start spreading it then water it in.

Won't be an over night fix but it will improve over time.

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There are two ways you can solve your problem with the sand -

  • Build up the composition of your sand with the addition of fine clay particles or by the addition of organic matter such as compost. Do not add this in layers but mix it in as well as possible.
  • OR
  • The other alternative is to use plant material that will grow in sand or well drained soils - have a look at coastal vegetation for ideas. There are palms and casurinas ,that will do okay. Malay Grass will handle low fertility sandy soils quite well for turf . There are succulents for colour and plants like lavender (think Mediterranean style) that will adapt. Numerous other plants that will survive in sandy soils if you do a bit of research.

Sorry to go off topic, but how does one obtain organic matter?

I wouldn't dare have a compost heap here as it would be breeding heaven for snakes?

Relying on the 'right' plants is problematical - as it depends on sun/shade etc.

Additionally, how does one find fine clay particles? Another genuine question as I'd love to add some clay to the soil to retain water.

I bought a lavender plant once (only time I've seen it sold here) and it quickly died. Not sure whether it was not enough/too much water or too much sun.

The only shrubs that survive well in v dry soils are frangipani and bougainvillea in my experience.

Looking for clay particles - if not available at a nursery which i doubt then find some clay and dilute in water and then apply the water infused clay to the sand. There is also a clay available for use in sealing dams and ponds called Bentonite (sorry i don't know the Thai word for it) that if used sparing could be used as an absorbent. Also Vermiculite or Perlite commonly used in Hydroculture could be used instead of clay .

Organic matter can be added by not only compost but by tilling in coconut fibre, grass clippings as somebody else suggested, green manure crops may be worth a trial, or any other "organic material one finds in the garden. It will take time and some effort but it will work.

There are many different forms of composting - i doubt if all of them would attract snakes . A Barrel compost tumbler bin may be one solution.

" Relying on the 'right' plants is problematical - as it depends on sun/shade etc."

That is why i suggested looking at coastal sites and the vegetation it will support ,particularly if the base growing medium is sand. One always has to consider sun /shade and other factors when planting out a garden.

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While on this subject and not wishing to hijack it can anyone tell me please where I can purchase some lawn weedkiller/feed thumbsup.gif

I don't think you can buy lawn weed killer in Thailand. I bring a couple of bottles of Weedol with me whenever I return back to the UK.

Thai Watsadu sells bags of 16:16:16 pelleted fertiliser which does the job. (Other places like Homepro, Boonthavorn don't seem to carry it.) I think the brand's called "Rabbit". 3 kg bags. There's at least one other mix, but my (limited) understanding is that 16:16:16 is OK for grass.

Incidentally, I strongly suspect that Weedol kills Malay grass. (I now think the broad leaved invasive weed in my "lawn" is Malay grass thanks to previous posters. It definitely dies off after I apply Weedol.)

Thank you wai2.gif

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Xen, Overherebc and others have some good suggestions for gradual soil improvement. But you have inherited an ongoing challenge with this situation and I would offer a more extreme option.

If landscape plantings without the very limiting restrictions on what will grow in sand are important to you, I would dig out and remove the sand and replace with a loamy topsoil in the planting areas, and incorporate organic matter at the time of soil replacement. (Loam is a more balanced amount of clay, silt and sand sized soil particles, as opposed to the dominant sand texture you have described.)

Yes it's a big project and could be expensive, but if you have the budget, contractor and soil resources to do it all at once, it will take away some of the pain of gradual soil improvements over several years that have been suggested.

It's a good lesson for those who are building, buying or renting property. If the landscaping is important to you, get involved in the site preparation early on. Assess the soil before you acquire the property, and insist on quality topsoil in the areas that you anticipate landscaping, before you find out the hard way like the Oxx.

Good soil is the key to plant health, nutrient availability, resistance to pest and disease factors, and water efficiency . With sand as soil you will be spending more time and money on watering and fertilizing and constantly trying to upgrade the quality with imported materials.

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If you can aerate the sandy soil ( poke deep hole in it) and then topdress with organic matter, it will solve your problem.

To aerate, use a spading fork and male holes about every 8 inches over the entire area.

Then top dress with organic matter and water it in well.

The best organic matter I have found in Thailand is shredded coconut husks. I buy it in 4 cu ft bags for about 80 baht a bag.

The problem with sandy soil is that it does not retain any water or fertilizer, but it is great for root growth if you can keep it moist.

P.S. I was a horticulturist and landscaper in my previous life and I am confident that my advice is good!

This is the tool I am referring to and they are available in Thailand.

post-147745-0-07315600-1462631131_thumb.

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When you mow the lawn do you remove all the cuttings or leave them to 'mulch' back in ? Leave the cut grass to rot back in.

Every couple of weeks or so buy a few bags of soil from your local garden centre and start spreading it then water it in.

Won't be an over night fix but it will improve over time.

Back in the UK it seemed obvious to leave the grass mowings to mulch back into the lawn, as my interest was in the flower beds - so the lawn had to make do with nothing more than being mown and the dandelions/bindweed etc. being gradually dug out (a never ending job).

Living here, I employ gardeners to come in every couple of weeks to mow the grass/cut back bougainvillea and bamboo/remove all the fallen leaves. You make a v good point, that I need to tell the gardener to leave the grass cuttings rather than taking them away smile.png .

I'm honestly not exaggerating - I've put hundreds of bags of soil in the flower beds over several years, and you're right insofar as the soil is slightly better - but only slightly....

There must be a way to compost the multitude of tree leaves as I expect they'd break down v quickly in this heat? But as mentioned before, I daren't build a compost bin as the snakes would love it as a breeding ground.

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