Gravel in the bottom of your container?
There are a lot of things that we have always done because our Mothers and Grandmothers did it that way, and they always had success, so why mess with success? But is the old way best? Maybe we should be doing it differently now. But how do you know which is right and which is wrong?
Do we need to put gravel in the bottom of our planters? I say no gravel needed in planters
I believe that it’s wrong to put gravel or other “drainage helpers” in the bottom of your planters. You are just making it heavier and taking up valuable space that roots could use to access more nutrients and air exchange in the soil.
Gravel doesn’t provide drainage for the soil. The soil will hold the water until it is saturated anyway. And the gravel does the opposite that you think it is there to do. It creates a barrier.
In horticultural classes they will teach you about “perched water tables” or PWT. It has to do with Gravitational Flow Potential (GFP) and capillary action. The PWT is water that occupies a layer of soil that is always saturated and won’t drain at the bottom of the pot. It can evaporate or be used by the plant, but physical forces won’t allow it to drain.
It stays there because the capillary pull of the soil at some point equals the GFP. So the water won’t drain, it is “perched”. This is the area of the pot where roots seldom penetrate and where root problems begin due to a lack of aeration.
Update: 2/21/2016 Garden Gate magazine has a small article about this same thing. So happy to see this. http://www.gardengatenotes.com/2016/02/16/improve-container-drainage/
So why waste the space with gravel?
Instead, use a coffee filter. Use some folded newspaper. I have even used a sheet of vinyl screening. Cheap and plentiful . Coffee filters are a perfect size to go into the bottom of any container, and they can be cut easily to fit square or very tiny pots. Obviously, we know they drain well. And they create a barrier over your holes to keep some bugs out, especially slugs.
If you have a large planter, don’t half-fill it with bricks or plastic bottles or packing peanuts. Just use a smaller pot or go ahead and use another bag of potting soil. It is worth it in the long run.
And lest we forget, be sure you have HOLES in the bottom of your containers. Even these porous hypertufa planters need holes in them, because the most typical cause of the death of a plant (especially succulents) ……is root rot from too much moisture.
Here is a short video showing how easy it is to drill holes in hypertufa.
Remember to elevate your planter too. These troughs need a pedestal, pot feet, or a foot of some kind to keep those drainage holes from being blocked by the surface they are sitting upon. If these containers are wintered outdoors, it is best to have them off the ground to prevent any waterlogged freeze, if possible. Anyway, they are cuter to me when they have little feet!
Alternatively, how about making a pedestal ? which I wrote about here.
Succulents grow best with great drainage in these bowls, troughs, and containers, so be sure to add perlite or poultry grit and mix it into your soil. You want the soil to be free-draining too, just like your hypertufa container itself. The hypertufa planter will let moisture in and out, and air into the soil and into the roots. The irregular surface of perlite is what helps to aerate your soil mixture.
So let me know what you think. Do you put gravel or “stuffers” into your containers? Why or why not?