Clay or plastic, round or square, full size or half size? Appearance, weight, ease of cleaning, and the shape and size of a pot are your primary considerations.
Does the appearance of a pot matter? Probably not, unless you plan to enter a competitive show in which case it’s a good idea to grow your finest specimens in your nicest pots or even splash out on a fancy clay one. If you are looking to display a plant in a decorative way, then you can’t go wrong with a nice glazed clay pot. With unglazed ones you may get efflorescence cause by minerals in the clay and compost.
There are many fancy pots available at garden centres and a few specialist potters make them but they are too expensive for use in a collection. In the USA, the ‘staging’ of plants (ie, the overall appearance of a plant and its container) is very important when it comes to competitive showing.
Clay pots are more expensive and they weigh considerably more than plastic which only adds to the overall weight of a pot that’s already filled with heavy compost and, possibly, a heavy water-filled plant.
Many growers say that because the roots get stuck to the sides of clay pots they can be damaged when you remove them. However, repotting may in any case risk damaging the tips of roots so if you repot before the plant starts growing in the spring this won’t matter too much.
Plastic pots are cheaper and lighter and easier to clean, and the major brands come in standard sizes which can make arranging all your plants in a greenhouse a little easier. Most are terracotta in colour but you can get then in other colours, particularly from eBay. Sankey and Ward are the most popular brands but there are others.
Some older BCSS members still swear by square pots once made by BEF (British Engineering Foundry, the original makers) which have recently been remade in limited quantities from the original moulds. There is also a thriving trade in second-hand BEF pots particularly among older growers. While the original ones were undoubtedly good quality, they do look quite tatty after a few years and I’ve never understood the obsession some people have with them.
Plastic pots don’t last forever because UV light degrades them. The biodegradable versions should be avoided altogether as they only last a couple of years.
Reserve your best pots for your collection plants (and the very best for your show plants) and use the less attractive ones for propagation and seed-raising. I find myself accumulating plastic pots in all manner of sizes as a result of buying plants from other growers. Those with large or numerous holes are better for growing garden plants. Avoid throwing pots away and try to recycle them where local facilities exist.
If a plant gets pot-bound you may need to break a clay pot to get it out. Where roots have grown through the bottom of a plastic pot I often cut down the side to free it without breaking off the roots.
Round vs square
Square pots, such as the BEF ones, are thought by some people to be easier to fit onto a large trays on a greenhouse bench but you can fit round pots very well on a tray by arranging them in alternate rows. Round pots are also much easier to arrange when you do have different sizes, although it’s better to keep to regular pot sizes if you want to arrange your plant optimally.
Keeping things clean
No matter which type you choose, wash your pots between uses with very hot water and lots of washing up liquid and then rinse them with hot water. Use rubber gloves so you can withstand a higher temperature. Clay pots are a faff to wash but you can use a pan scourer; while I have never dared try this I suspect they would clean nicely in a dishwasher!
In theory, clay pots could harbour pathogens but you can always put them in the oven at 100C for an hour or just microwave them.
Other pot types
Half pots and bowls can be very useful. As pots get larger they get taller, but most cacti and succulents have shallow roots so they don’t need the depth. (An exception is where the plant has a prominent tap root.) A deep pot requires more compost and make the whole thing even heavier. Bowls are great for large, shallow-rooted cacti. The rim size is what matters when you are choosing a pot for most plants.
Hanging pots are perfect for dangling plants, including cacti such as Selenicereus and the many epiphytic species, and succulents like Ceropegia woodii. The cheapest types are plastic, with an integral saucer (essential to avoid water falling onto the plants below), and clip-on rigid plastic ‘ropes’ .
You can also buy hanging pot holders, inside of which you put a plant pot. These are more expensive but come in all kinds of fancy designs and colour. These are better if you are going to bring a plant indoors at any point. The ‘ropes’ have a habit of breaking after a couple of years as the materials may not be UV stable.
Pot size
Avoid over-potting a plant; that is, putting it in a pot that’s unnecessarily large as the compost will remain wet for longer after watering, which you don’t really want. I have found myself down-sizing some plants when repotting them, having been over-optimistic about how quickly they would grow. While cacti and succulents planted in open beds will result in some huge specimens, many don’t respond in this way and those that do you probably don’t want to.
Gravel in the bottom?
A study was published a couple of years ago saying that adding gravel to the bottom of pots makes not the slightest bit of difference to how plants grow. I use larger gravel (10-15mm) to fill the holes so that the sandy compost does not wash out.
You can buy larger grades of gravel at garden centres that are perfect for the holes in most flower pots. For pots with larger holes you can either use larger gravel or pieces of broken clay pots.
Terrariums
Cacti and succulents will NOT grow in a terrarium!
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