Drainage In Containers

Hi All,

Watched this video recently and think I might be getting it wrong. I tend to add some grit and/or sand to the soil mix depending on the plant but always put crocks over the drainage holes and then add grit until it covers the highest point of the crocks. But scientifically, what I'm doing doesn't seem to make any sense. What do you guys typically do and has anyone tried both ways and compared results?



Thanks,

Nick

 

The simple test is incomplete because it did not show improved drainage capabilities for plants, the most important result.

He needs to repeat the tests by growing plants, say, rosemary (or other drought-loving plants) in the two different mixes and use the health of the plant to measure successful drainage.

 

I viewed this clip, and yes and no.

Basically for container grown plants, bulbs etc. The matter of drainage is important. Lets take a look. Bulbs and corms in particular are prone to base/basal rot. So whether planted in containers or open ground local conditions have to be considered. Thankfully in most cases, with bulb and corm planting, a sprinkling of course grit applied and the seating of the subject thereupon will be enough.
The importance of good or effective drainage is to avoid the baseplate of the bulb/corm from rotting. Likewise. The planting albeit container or open ground for plants and shrubs is to provide protective drainage to that part of the plant, where the stem ends/starts and the roots begin to grow. This really is the most important area. So a handfull of grit etc will not go amiss around the base when planting.

Relating to the remainder of the container. It must be taken into account. Soil/compost in a container soon becomes compacted. So also soil in the open ground. Here in the open, natural forces play their part. Mycela roots, earth dwelling bugs etc all play their part. The natural elements included. In a pot or container. The 'world' of the captive plant is so limited.

So. Having comfotably planted our subject. The base is catered for, what about the rest of the soil/compost. Herein the roots spread out and search for food. Now moisture enters, stage left. Illustratively we all know. Moisture in our homes, leads to mould. This also happens within container compacted soil/compost. Here nasties can take over and sadly your plant may be doomed. So, yes add drainage to the compost, grit, perlite etc. Try and maintane a claen compost.

 

Drainage of a pot (or any soil for that matter) is a function of the consistency of the soil itself.
If soil in a pot is filled with thick sticky clay,no matter how many crocks one uses, the root growth for a lot of plants will by poor.
And the opposite is also true that an open mix with plenty of grit or perlite in it will produce better results.

I have grown cacti and succulents for 30+ years and have never used crocks, but with plenty of grit.(roughly 30% by volume). My plants do well!

 

With pots on a flat surface you need to raise them slightly so that the water can drain away after it has run through the compost and grit mix.

 

I drill extra holes in plastic containers on the sides half an inch up from the base so dont need the feet. Stone and terracotta pots go into the shed away from the frosts.

Palms are now potted up with generous doses of perlite added to the mix as well as the usual sharp sand.

 

I only really worry about drainage of plants that are likely to stand outdoors all winter, things that are out in summer but undercover in winter just get extra grit added to the compost when potting depending on plant.
Usually in summer, in plants other than succulents, out doors, getting enough water into the container is the problem.

 

Thanks for the interesting and informative replies everyone, forgot about starting this thread! I'm thinking of experimenting with just mixing in the drainage material with the soil and not having any grit at the bottom of the container. But most of my pots are glazed terracotta and I think I'll need to add even more grit to the mix, since they seem to be getting a bit waterlogged ATM. So how do I prevent the soil from falling out of the drainage hole(s)? Should I simply use crocks? In the comments section of that video someone mentioned used dryer sheets or sheets of window screen, but I have no idea what those are!

Nick

 

Im guessing the window screen is the mesh screen thats part of the window that keeps the bugs out when you open the window. Its a US / Asia/ Africa thing.
I would have thought it would clog up quickly here with mud. I would just use crocks or broken up pieces of styrofoam.

 

Yes , using crocks etc is whats always been used to hold the compost in the pot, so would not worry about using mesh etc.

Its an interesting video to watch and the keynote of his demo is the waters lack of movement between the compost and the gravel.

This may be as he says due to the lack of water transference between the two mediums, however as he shows its really that its due to the composts ability to hold onto the water.

What he also fails to show is what its like in real gardening terms.

If you have a base layer of gravel or hardcore etc, when we often use in the outdoor pots to stop them blowing over, the compost will steadily work its way down into the gravel by movement, watering and the plants roots, so that there is no clear difference between the gravel and compost that he trys to demonstrates.

Storm in a plant pot, we would suggest

 

IME, the (often) single hole in a terracotta pot does clog up with soil or compost and roots. I recently emptied out some pots half-full of water that had an effective 'bung' of compost in the hole. A slightly curved crock over the hole should prevent that happening.

 

@ARMANDII I tried using MPC initially with pots and got better results. I then tried using my heavy clay soil to save money but it was a disaster as you can imagine, no matter how much grit I added to it! So now I'm mostly using John Innes No3 which will hopefully get the balance right... I usually tend to just grow plants which are compatible with my soil or try to adapt it, so I'm basically new to container gardening.

Nick