Choosing Pots and Containers: Material, Size and Drainage

Most container-growing failures are decided in the shop, before a plant is anywhere near the pot. A container is not just a decorative object with soil in it — it is the entire environment a plant's roots will live in, and three choices about it determine how much work you do and how well the plant grows: material sets how often you must water, size sets your margin for error, and drainage decides whether the plant survives at all.

The trouble is that the prettiest pot in the aisle frequently gets all three wrong: no drainage hole, too small, and in a material that fights the plant. This guide covers each decision honestly, then matches containers to what you actually want to grow.

Material: Your Watering Schedule, Decided

The FAQ's core insight is that this choice is really about porosity. Everything else follows.

The honest way to choose: match the material to the plant's water preference and to your own habits. Someone who overwaters should buy terracotta; someone who travels should buy plastic or self-watering. The pot can compensate for your tendencies if you pick it deliberately.

Size: The Most Underrated Decision

The FAQ is emphatic, and it is worth restating because it is the single biggest lever on success: more compost means more water, more nutrients, and more forgiveness. A generous container tolerates a missed watering on a hot day; a small one is dry by lunchtime and the plant stressed by evening — which is exactly the daily crisis balcony growers know well.

• For new outdoor plantings, err large. Especially for vegetables, tomatoes, and anything expected to perform through summer heat.
• For indoor repotting, go one size up only — the repotting guide's rule. Too much wet compost around too few roots causes rot. These two pieces of advice are not contradictory: one is about choosing a container for a plant that will fill it, the other about moving an existing root system gradually.
• Depth matters as much as width for root crops, and width matters more for shallow-rooted, spreading plants.
• Fewer large pots beat many small ones if you have to choose — better growth, less watering, and a tidier look.

Drainage: The Rule With No Exceptions

Per the FAQ: drainage holes, always. A holeless pot is a reservoir, and roots sitting in water suffocate and rot. Two workable solutions if a decorative pot has no hole — drill one, or use it as a cachepot with the plant in a plain holed liner you lift out to water and drain.

Two related myths worth retiring:

• Gravel or crocks in the base do not improve drainage. They just reduce the volume of useful compost. Holes plus free-draining compost is what drains.
• A saucer left full of water defeats the drainage holes. Saucers catch run-off; they are not reservoirs. Empty them, particularly in winter and for plants that hate wet feet.

Pot feet or any small elevation help outdoor containers drain freely and stop them sitting in a puddle — which also, per the winter guide, is what prevents freeze-cracking.

Weight, Mobility and Where the Pot Will Live

• Wet compost is heavy. A large ceramic or concrete container, once filled and watered, is effectively immovable — decide its final position before you fill it.
• Balconies and roof terraces need the weight conversation the balcony guide raises: favour light materials and composts, keep the heaviest containers near the wall rather than massed at the outer edge, and check your structure if in any doubt.
• Windy sites want low, heavy and stable — tall lightweight pots blow over, taking the plant with them.
• If a plant needs to move seasonally (tender plants going under cover, per the winter checklist), either keep the pot liftable or put it on a wheeled plant stand from the start.
• Group pots together where you can: they shade each other's walls, raise local humidity, dry out more slowly, and are quicker to water.

Self-Watering and Fabric Options

The FAQ's verdict, expanded: these are situational tools, and knowing when they shine is the whole point.

• Self-watering containers buffer missed waterings and deliver consistent moisture — genuinely transformative for tomatoes, peppers and other thirsty crops on a hot balcony, and the reason a summer holiday becomes survivable. Avoid them for plants that want to dry out between waterings.
• Fabric pots breathe superbly, produce excellent root systems, make overwatering nearly impossible, and fold flat for winter storage — at the cost of needing watering more often and looking utilitarian.
• Both pair well with drip irrigation: the irrigation guide's timer-and-dripline setup solves the fabric pot's thirst and tops up self-watering reservoirs automatically.

Compost: The Other Half of the Container

A pot is only half the decision — what goes in it matters just as much, and one rule is absolute: do not use garden soil in containers. It compacts into a dense mass, drains badly, and brings weed seeds and pests with it. Beyond that, match the mix to the plant. General-purpose compost suits most things; succulents and cacti want a gritty, fast-draining mix; orchids need bark rather than compost; and permanent plantings such as shrubs and small trees do better in a loam-based compost, which holds its structure for years instead of breaking down in one season. It is also worth understanding that bagged compost is a nutrient store with an expiry date — most contain enough feed for a matter of weeks, which is why every container guide on this site insists on regular liquid feeding once plants are growing strongly. For large containers you do not want to replant, top-dressing (scraping off the top few centimetres and replacing it with fresh) refreshes nutrients without disturbing roots, exactly as the repotting guide describes.

Frost, Longevity and the Cost of Cheap

Two practical realities shape what a pot actually costs over its life. The first is frost: terracotta and glazed ceramic full of wet compost can crack when water inside them freezes and expands, so anything staying outdoors through winter should be genuinely frost-proof rather than merely frost-resistant, or moved to shelter as the winter checklist recommends. A cheap pot that shatters in its second January was not cheap. The second is that pots do not wear out in the way most garden equipment does — which makes secondhand an unusually good deal here, and means a well-chosen expensive pot can genuinely last decades while plastic ones become brittle and split after a few seasons in sunlight. The pragmatic strategy that most experienced gardeners land on: plain, cheap pots wherever they are hidden or temporary, a smaller number of good frost-proof pots where they are seen and permanent, and the cachepot trick — a plain holed pot inside a decorative one — to get the appearance of the expensive option with the practicality of the cheap one.

Matching the Pot to the Plant

Grouping Pots: The Trick That Cuts Watering

One arrangement decision quietly reduces the workload of a container garden more than any product: group pots together rather than scattering them. Clustered containers shade each other's sides, raise the humidity in the air immediately around them, and shelter one another from drying wind — with the result that each pot dries out noticeably more slowly than it would standing alone in the open. It also concentrates the watering round into one place instead of a tour, makes drips and saucers easier to manage, and looks considerably better than pots dotted about singly, which is the same visual point the design guide makes about planting in groups. Put the thirstiest containers in the middle of the group where they get the most shelter, and the drought-tolerant ones on the sunny outer edge.

Buying Well and Buying Less

A few practical notes that save money and waste. Standard sizes are worth sticking to, because they nest, stack and interchange with liners and saucers. Second-hand pots are abundant and cheap — a wash and, if you are cautious about disease, a rinse with hot soapy water is all they need. Old pots that have gone brittle in sunlight can be recycled where facilities exist, and the sturdier ones last decades. And plenty of perfectly good containers were never sold as containers: buckets, crates, olive tins, half-barrels and stacked tyres all grow plants happily, provided you can put holes in them — which brings the reduce-plastic guide's central point back around, since the most sustainable container is one that already exists. For edibles, just check that anything repurposed did not previously hold something you would rather not have in your soil.

The Classic Mistakes

1. Buying the pretty pot with no drainage hole and hoping careful watering will do.
2. Choosing too small, then fighting daily thirst all summer.
3. Ignoring material and wondering why terracotta herbs dry out while plastic succulents rot.
4. Adding crocks instead of drainage holes.
5. Filling a huge pot in the wrong place and discovering it cannot be moved.
6. Leaving saucers full of water, undoing the drainage you paid for.

The Bottom Line

Choose containers with the three decisions in mind and container growing gets dramatically easier. Pick the material to suit the plant's thirst and your own habits — porous terracotta for dry-lovers and overwaterers, moisture-holding plastic or self-watering for thirsty plants and absent owners. Go generously large for anything you want to thrive outdoors, while stepping up only one size at a time when repotting indoors. Insist on drainage holes, skip the crocks, empty the saucers, and raise outdoor pots off the ground. Then site heavy containers before filling them, group pots to slow drying, and remember that a repurposed bucket with holes in it grows a better tomato than a beautiful sealed urn ever will.