Rocks on top of soil!

[Samsquatch]

When I water my cacti, I notice that the soil does not stay moist for very long, and I heard that it stays moist longer if you put rocks or pebbles on top of the soil. Does anyone have any recommendations on what kind of rocks to use? Would it negatively affect the plant if I just grabbed random rocks from my yard and used those?

[7george]

My home atmosphere is very dry and I use rocks to retain moisture in the soil, also to make surface looking nice. My preference tends to quartzite and granite rocks but limestone works well enough too. Most times the mix I buy contain all types of rocks and if I get crank start to sort them out, like limestone to astros and turbinis and acids to south Americans but not sure if they like this or not...

[DaveW]

I think grit top dressing over about quarter inch size grit is supposed to act the same. It acts as a condensation trap for the evaporating water, returning it back to the soil thus slowing down the pot drying out. Whether the size of rock makes much difference I do not know?

Our problem in the cooler UK though is getting the pots to dry out quickly enough, the reverse of your problem.

[Samsquatch]

My home atmosphere is very dry and I use rocks to retain moisture in the soil, also to make surface looking nice. My preference tends to quartzite and granite rocks but limestone works well enough too. Most times the mix I buy contain all types of rocks and if I get crank start to sort them out, like limestone to astros and turbinis and acids to south Americans but not sure if they like this or not...

Okay, I think I have a lot of granite, so I'll try that out. Thanks!

[jfabiao]

I favour quartzite as top dressing because it changes hue if it's moist from below (don't know why exactly).

[thomas]

I usually use aquarium gravel. The lighter colored gravels seem to have mare quartz. Some people don't like top dressing but I find that it helps to distribute the water evenly around that pot as I water.