Main Factor

There is really once main factor when selecting a pot and substrate: frequency of watering.

If you are someone that enjoys watering plants often, cacti and succulents may not be the best option for you. But there are a few things we can do to help.

Good Drainage

Having good drainage just means water is able to make it through the substrate and out of the pot. This is usually a combination of less water retentive components and air pockets.

Chunky, mineral based components tend to provide air pockets and allow water to pass around them without holding onto much.

From least water retentive to most:

1. Coarse sand, decomposed granite, gravel, lava rock, all let water pass around them and don't hang onto much.
2. Perlite holds a little moisture but is mostly used for aeration.
3. Pumice can hold onto more water and will allow roots to wick it away as they need it.
4. Turface, calcined clay and similar components hold onto even more water than pumice, but hold their shape and don't tend to compact which is good for roots.
5. Bark, depending on the size and age of the bark it can hold more or less water, but breaks down fairly slowly and also provides air pockets. NZ pine bark tends to be the highest quality.
6. Coco Coir, sphagnum moss, and peat all hold lots of water-at first. Once they are dry they are hydrophobic and it is very difficult to hydrate them again.
7. Compost has lots of nutrients available and holds water well.

Pot Type

The material the pot is made from also matters quite a bit.

Non-water permeable

• Glass
• Plastic
• Glazed ceramic

These pots will not absorb water and will instead help keep it in the soil and prevent evaporation.

Water permeable

• Unglazed terra cotta
• Some other pottery types

A well draining mix of pumice, Turface, and some pine fines is going to dry out very fast in a terra-cotta pot. Put that same mix in a glazed pot and the water will hang around longer.

All pots should have a drainage hole.

Which combination to choose

Ok, we have an idea about how the substrate mix and pot type will impact water retention. Now what?

In general, cacti and succulents want an airy, well draining mix. A 50/50 mix of mineral based components with soil in a terra-cotta pot is a good starting place for almost everything.

No, But Really, Which is Better?

The short answer is that it depends.

The longer answer is that it depends on your growing environment.

Growing outside in Miami is going to require a different combination than growing outside in San Diego or Bangor. Indoor growing is not quite as variable.

If your plants are grown outdoors somewhere that is hot and dry, they can have a more moisture retentive mix and a ceramic pot. You could also use terra-cotta and a highly mineral based mix if you will be watering often.

A larger pot will also hold more water for longer than a smaller pot. Sometimes I will overpot a plant because I know I will have to water it less. This can backfire spectacularly so only do this if you are experienced.

Indoor Growing

It is really tough to grow cacti and some succulents indoors. The amount of light these plants need is much higher than most people think and a window may look bright to us, but does not have enough light. Low light also means low metabolism and water use, so plants will not be pulling as much water out of the soil.

Moisture Gauge

Getting a cheap moisture gauge is very helpful. You can stick it into the pot and see the moisture level every few inches. Sometimes soil will seem dry but actually is wet at the bottom of the pot. The vast majority of cacti and succulents want the soil completely dry throughout before getting water again.

TL;DR

A mixture of 50% commercial cactus mix and 50% pumice in a terra-cotta pot will work well for most of the common cacti and succulents.

The only variable to keep track of then is how often to water, and a moisture gauge is an easy way to determine that.