Debunked: crocks in plant pots helps drainage

Using crocks helps prevent compost escaping through the drainage holes and by adding weight it can help prevent pots falling over if the plant makes them rather top heavy. That’s my argument for continuing to use them.

Can the “crocks” be recycled? Or will they just end up in the general rubbish? So using them at the bottom of flower pots would be a good way to avoid unnecessary landfill use.

My crocks have probably been reused many times because new ones are less easy to obtain thanks to the move to plastic pots. I have a plant pot with my stock. No doubt you have heard of the term: “A load of old crocks”. 🙂

I use anything as long as it`s not going to harm the plant. However, will now not worry so much about drainage, particularly in small pots. Thank you Which? Mind you if your plants are keeling over in the wind because they are top heavy perhaps you should put them in a wider base pot.

I stopped using crocks after being so advised on one of the TV gardening shows (I think). Now I don’t know what to do with all those broken pots (lots after this winter, for some reason). But putting crocks at the bottom of containers doesn’t seem to make any difference – and, in fact, they do get embedded in the compost, and prevent drainage. So I’m no longer putting them in.

Hi,
I have been putting crocks in pots for many years and have just learned something new : )
However I find putting a few crocks in the bottom also helps when taking a plant out if its become a bit pot-bound. It just takes something as thin as a pencil to push the crock up and the plant out.
There`s something comforting in old crocks or an old beach pebble or two. I once dropped a
favourite blue and white cup on the floor of the greenhouse and used pieces of it instead of crocks. There they stayed for years until I forgot about them, it was like seeing old friends again `Oh, hello, there you are!`
I guess I`m just an old crock too : )

Sounds like a load of old crocks to me !!!!! What did they do….cement the crocks together???

Putting stones, pebbles, crocks, etc does help drainage. If there is water in the the saucer, the compost soon gets smelly if there are no crocks in the bottom to raise the compost.

Crocks also give the pot weight to stop it falling over.

Crocks also help roots to stay in the pot.

Crocks also reduce the amount of compost needed.

Sorry, you haven’t persuaded me to give up using crocks.

I will do my own test trial this summer.I have two large identical tubs either side of the steps
in the garden.One will have terracota crocks the other nothing.I will report the outcome in
due course.

I cut circles of fine aluminium mesh from Halfords. They allow easy drainage and prevent insects getting into the pots.

Interesting – I use pebbles, crocks, polystyrene, newspaper (not all at the same time!) to stop the compost blocking up the drainage holes & slipping out. I don’t suppose it matters to any great extent whether thee does, or thee doesn’t .

The reason we put a few pottery crocks in the bottom of pots is because the pots on the terrace stand in large saucers or trays so that when watering them any run-through is captured and reabsorbed as the soil dries out. This seems to work so we don’t think we’ll be making any changes. We don’t use fibrous compost for more than about a third of the fill mixing it with garden soil which is on the sandy side and prone to running through the drainage holes. This seems to suit the plants very well and we usually have healthy growth and good blooms or foliage as appropriate. I share Chris’s and Beryl’s reaction to the research report; it’s strange what they think is crying out for such earnest research these days.

I am a trifle upset that this research apparently has not been extended to considering the benefits of terra-cotta on stabilising the temperature of the roots.

” And, young or old, the roots are usually not has hardy as the plant’s top. American holly (Ilex opaca) is hardy to USDA Zone 5. The top part (stems and foliage) of the plant will survive to a temperature of about -20 F, but immature roots die at 23 degrees above zero, and mature roots at nine degrees. In the ground and insulated by the earth, that’s usually no problem for the roots of hollies in Zone 5 where the average minimum temperature is -10 to -20 F. But in a container, root damage in American holly would begin to occur at 23 degrees if left unprotected — a drastic difference from -20 degrees.”

Fortunately we do not have these temperatures but the principle remains the same that excessive heat and cold are not good for roots.

My belief is that the crock provides thermal benefits besides stabilising the plant pot. There may also be ,on very hot days evaporative cooling, which will also be of benefit.

So as it stands the Which? research looks partial and to be honest does not instil me with any confidence as there is no methodology or source research to link to. Perhaps Which? can provide a link please.

There is nothing wrong in using old crocks, been doing it for years and never had any problems with drainage or root rot. If using good friable compost you wont have any trouble. Using plastic milk containers and other plastic materials is also very good in very large pots. saves having to fill the pots with lots of compost and easier on the pocket too

I have stopped using crocks and have changed to gravel and found that its weight helps keep pots stable and gives improved drainage.I am also an”old croc”