sand as mulch or seed cover?

I have some sheet mulch beds, and some tilled area. I planted seeds in both. In both, I dug a furrow and put the seeds in the bottom of it, then covered them with compost. The compost seemed to act like a wick and dry the seeds out.

Would it work to dig a small trench, say six inches deep, push the seeds into the bottom of it, and fill the trench with sand?

The benefits I could see would be:

The sand would stop evaporation.

The sand would let water quickly sink to lower layers.

The seeds would easily push up through the sand, allowing for deeper planting then otherwise possible.

And the sand should deter slugs, snails, and pill bugs.

Gilbert, I like your idea about using sand as a mulch, and the University of Arizona's College of Agriculture and Life Sciences agrees with you on the matter. Here is what they wrote about sand as a mulch.

The one thing that's made me hesitant to use sand around trees is how it plays with the idea of using leaves, flowers, and such that drop from the trees to enrich the soil. It wouldn't do the same with the sand. Would one save the leaves and other detritus and then dig out the sand periodically to add this below it? Something else?

Any ideas on ways it could be workable while still adding nutrients to the soil through plant matter?

Oh, and Gilbert - yeah, you're absolutely right on the wicking. A study on how much water mulches (not the dirt under them) retain and lose through evaporation pretty much bears that idea up.
EDIT: whoops, forgot to include the study! (http://ucanr.edu/sites/UrbanHort/files/80238.pdf )

Hello Shauna and Dave,

Thanks for the comments and links!

I don't think I would include sand in a large scale perennial garden, due to the problem of returning organic matter. My current plan, which I will post in another thread, is to use a combination of sand mulch, rock mulch, hugelkultures, waffle gardens, and ollas to create a drought resistant bed in an annual garden. The hugelkultures should add enough organic matter so that I can wait a few years while just adding liquid fertilizer through the ollas. Then I would dig in the small amount of sand while adding more logs, manure, etc.

I will see how it works. And I look forward to the commentary on my next thread.

I look forward to hearing about it! This is something I've played with a little myself (some unintentionally due to rock mulch on my property when we moved in). The sand I just heard of last year and played a tiny bit with it in a waffle garden, but not much else yet.

Just to share what my experience has been, in case it helps.
I'm living in a desert where for three months out of the growing season, the average temperature is above 95 F. And after my experiences with sand and rock mulch, I started doing a little research into where rock and sand mulch have been traditionally used and discovered that in these cases (like the Colorado Plateau and Gansu province in China, as that article mentioned) the average temperatures are about 10-15 F below this in the hot months.

This difference in temperature has really impacted the areas where I have sand or rock mulch. The reflected heat is increased with the sand/rock. A study in Georgia found that rock mulch can increase the temperature by around 10 degrees (this is my interpretation, anyway. They simply said what it increased the temperature TO, and I looked up area specific weather to estimate). I can hunt it down if your interested, although it was a little bit of a thing. During the cooler months, the water retention was enough that the increased reflected heat wasn't an issue. But when the higher temperatures hit, the reflected heat was brutal in some areas. Native plants usually did all right, but any garden plants fried up into nothing, no matter the water.

The successes I had with the rock mulch/sand have occurred in areas where I have shade, and in these places there was no issue with the reflected heat, obviously, and growth in these areas was good.

I didn't know what the conditions are for your desert, or how high the highs were, but again, just offering this in case it might be helpful to know for your own endeavors.


I'm thinking of trying a technique that's believed to be an old Anasazi version of rock mulch, of a sorts. I just happened to be present at Bandelier National Monument when one of the botanists there was experimenting to see if she could get it to work. They got large (5 inches across or more), flat river rocks and then placed them all around the seedlings after they came up. She was very happy with the results. I'm thinking this might be something to try where I am, which could be easily removed if they turn out to reflect too much heat as the temperatures climb.

I mix river sand in with compost and old soil but I would be reluctant to go all sand. Walk across a sandy beach barefoot on a hot day and you will see why all sand is not a good idea.

I got a 20 yd load of sand last year and I am using it to mix with my compost about 3/1 compost to sand to improve how quickly the water peculates into the soil , I use it in a trench where I plant ( I have never had pole beans take of like they do in this mix, It is working great and I will want more when I use the rest of this , the down side is sand is heavy ~! I try to only use 1/4 sand to encourage the worms