Since time immemorial, or so it seems, all gardening books and magazines have advised us to add a layer of gravel or a piece of broken crock to a container before filling with compost. We were always told that this would aid drainage and prevent soil from washing out of the pot. Now it seems that opinions have changed and decided that this practice is not such a good idea after all. This article which I found on the Balcony Garden Web site explains the reasons why.
After reading this post, you?ll never put gravel or other coarse materials at the bottom of pots.?Must find out, WHY?
Every time you prepare a pot for planting you add a layer of gravels in the bottom for drainage! But, is it really necessary or not required at all?
Adding a layer of gravel, stones or pot shards in the bottom of the?container is a common practice that most of the gardeners (old or new or even experts) do. But do you really need to do this? We say NO!
We have grown plants in containers successfully without adding gravels to pots, and there seems no problem with it. Our plants have done really fine and never suffered from root rot or drainage problem. Let?s find out why it is NOT NECESSARY TO ADD GRAVELS or other coarse materials IN POTS!
To support our claim, we refer to this educative article on Illinois University, according to them ?It is a myth that a layer of gravel (inside the bottom of an individual pot) beneath the soil improves container drainage. Instead of extra water draining immediately into the gravel, the water ?perches? or gathers in the soil just above the gravel. The water gathers until no air space is left. Once all the available soil air space fills up, then excess water drains into the gravel below. So gravel in the bottom does little to keep soil above it from being saturated by overwatering.?
See more at Balcony Garden Web