Q: About sand.


Sands (foreground)


Pinguicula corsica A: Sand is an important component of many carnivorous plant mixes. For example, adding sand to pure peat moss provides valuable aeration.

There are different kinds of sand. The most useful are ones derived from quartz. Silica sand is a nice example. It is a fine-grained sand used by sandblasters. Unfortunately, it is very difficult to buy because is it connected to Silicosis. I have read several times that quartz sand is very acidic. This confuses me, because it seems that quartz sand is just silicon dioxide, and should be relatively inert in water. So why is it acidic? I do not understand.

When buying sand, I recommend you look for sand intended for horticultural purposes. This sand is less likely to contain much salt. Meanwhile, avoid ocean sand for this very reason! I can't say whether or not sand marketed for playgrounds has salt or not, but I've seen numerous other writers advise against "play-sand."

Certainly do not repeat the error of one FAQ-reader, who tried using "builder's mix"---this is just dry concrete! Imagine the FAQ-reader's frustration, and my amusement, when he revealed his pots became solid chunks of cement. Hah hah hah! Pity the plants died, of course. But hah hah hah!

Large grain "sharp" sand is also useful. Click on this page's photograph of Pinguicula corsica to see what I mean by "sharp" sand. Those grains are less than 1 mm across, but they look like jagged bits of glass! (They are far too small to cut your skin.)

Before using any sort of sand, I recommend the possibly unnecessary protocol of cleaning it. Cleaning sand can remove the fine particulates which can impede drainage, as well as salts and other impurities that may poison the plants. It might also be a waste of time. I'm not sure.

I clean sand by filling a bucket halfway with the sand, then I run water over the sand while agitating the mix. The water usually becomes tan and opaque with particulates. Pour out the wash water, carrying away the particulates and salts. After a few such washings the water in the bucket clears and the sand is ready to use.

Page citations: Rice, B.A. 2006a; personal observation.