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Are Rocks at the Bottom of Pots Harmful to Plants?

Posted: Thu Mar 30, 2006 12:46 pm
by brendan
I don't know if this is the right forum but this is regarding houseplants in pots.

My standard operation is to do a layer of rocks in the bottom of a pot prior to putting the soil mix, then the sprout, then some rocks on top.

My question is: Is the layer of rocks at the bottom a detriment to any species, or can it be used for all.

Second: Is it pointless.


Posted: Thu Mar 30, 2006 1:58 pm
by Grey
Well, I use rocks sometimes. I haven't had any issues with doing so - if you have a lot of rocks you may have to repot sooner, but other than that, as far as I am aware, it is fine. I do it so water isn't sitting at the bottom of the pot from the plate and soaking the soil if I accidentally overwatered - the rocks act as a barrier IMHO.

Posted: Thu Mar 30, 2006 5:34 pm
by grandpasrose
Putting rocks or gravel, or broken pottery or popcorn styrofoam in the bottom of pots is needed to assist with drainage. Especially if the pot does not have any drainage holes in it. Very few plants like to sit in standing water, unless they are bog plants. Because the plants are not in the ground, where water can just seep away if there is too much, the rock keeps a bit of space open for the water to seep to if the soil is too wet.

To actually make this work more efficiently, you might try putting a coffee filter, old nylon stocking or something pourous between the drainage material and the soil. This prevents all the soil washing into the rock and filling up all your drainage so there is no where for the water to go.

Of course ideally, your pot should have drainage holes, and a tray underneath, in which case the drainage material is not as necessary, although I use it anyway.
I use a combination of all three, rock, gravel and pottery in all of my container planting, indoors or out. :wink:


Posted: Fri Mar 31, 2006 3:18 am
by opabinia51
I agree with val. Though, it's not 100% necessary as I have forgotten to put rocks and what not in several times and the plants were just fine.

Posted: Fri Mar 31, 2006 12:14 pm
by brendan
because i know this isn't rocket science i probably should have thought "well, in nature, sometimes the soil is rocky, and sometimes not"

but i figured i ask. I just planted seven cuttings of ivy in oval plastic pots for my office. I'm lucky because i have an office with huge picture windows in the front area so it's basically a greenhouse. So i start all my plants at home and then bring them in and out of the office as they need.

Posted: Fri Mar 31, 2006 3:52 pm
by grandpasrose
If you are ever in doubt about anything, you should probably check it out, you never know, you might be on to something!

You're fortunate you have somewhere with so much light. Most of us struggle trying to find enough light to get our plants started. Best of luck and have fun! :wink:


Posted: Fri Mar 31, 2006 4:04 pm
by brendan
i definately struggle at home. typical flat ranch with one big window.

thankfully i have my office to use as well.

Posted: Fri Mar 31, 2006 4:08 pm
by grandpasrose
Lucky guy! :wink:


Posted: Sat Apr 01, 2006 4:52 pm
by The Helpful Gardener
Rocks or broken pottery in the bottom are good for drainage and soil in the wild has plenty of that usually; we call the rest bogs, ponds, streams and rivers... :lol:


Posted: Sun Apr 02, 2006 6:34 am
by opabinia51

Yes, but rocks and broken pottery provide a medium (of air) for which water to pass out of the pot. They help a lot but, are not absolutely necessary.

Though, plants in pots definately need a really good soil, with water holding capacity and good drainage as well as lots of good nutrients. The one big thing about plants in pots is that they DEFINATELY need to fertilized with an organic fertilizer as the nutrients in the soil are quickly used and not to mention leach out of the soil.

Posted: Sun Apr 02, 2006 10:54 pm
by The Helpful Gardener
Air passing through the soil is gas exchange and that ain't all bad Opa...


Posted: Mon Apr 03, 2006 3:09 am
by opabinia51
Did I say that it was bad?