Plastic plant pots: a practical buyer's guide

Plastic plant pots are the unglamorous workhorses of gardening. They don’t get the attention that hand-thrown terracotta or galvanised zinc planters do, but they’re what nearly every plant in your garden centre, every tray of bedding plants you bring home, and every bare-root tree before it goes in the ground has spent its life in. There’s a reason for that: they work.

This guide covers what to look for when buying plastic plant pots, how to match pot size to plant, and the questions we get asked most often at our Fife nursery.

What size plastic pot do I need?

Pot size is usually the first decision and the one most often gotten wrong. Plants are forgiving of many things; getting the pot size right isn’t optional.

A pot that’s too small restricts root growth, dries out within hours on a warm day, and starves the plant of nutrients. A pot that’s too large holds more compost than the roots can use, so the unused compost stays wet, sours, and root rot follows.

Here’s a working guide based on plant type:

1 litre pots (around 11–13 cm diameter) — for plug-stage seedlings, herbs like basil and parsley, small bedding plants, and stem cuttings being grown on. The classic “starter” pot size.

2 litre pots (around 15 cm diameter) — for young perennials, established herbs, single tomato plants in their early stage, and most bedding plants you’d buy at a garden centre.

3 litre pots (around 17 cm diameter) — for established perennials, small soft fruit plants like strawberries or low-growing raspberries, and tomatoes through their main fruiting season.

5 litre pots (around 21 cm diameter) — for small shrubs, larger perennials, bare-root roses being potted up, and most container vegetables (peppers, aubergines, dwarf beans).

10 litre pots (around 27 cm diameter) — for small trees, mature roses, climbing plants on supports, and any shrub you want to keep in a container long-term. Around the largest size that’s still comfortably portable when full.

The simplest rule when potting on: go up two or three pot sizes from the current one, never more. Jumping from 1 litre to 10 litre in a single move is one of the most common ways to kill an otherwise healthy plant.

Are plastic pots bad for plants?

No. This question comes up so often that it’s worth tackling head-on.

Plastic pots have practical advantages over terracotta and ceramic. They retain moisture better, because their walls are non-porous — terracotta wicks water out through its sides, which is fine in a wet British summer but a problem in a dry one. They’re frost-resistant, where terracotta cracks if waterlogged clay freezes inside it. They’re far lighter, which matters when you’re moving a 10-litre pot of compost. And they don’t break when knocked off a bench by a curious dog.

The genuine downside of black plastic is heat absorption in direct sunlight. On a hot day in full sun, the surface of a black pot can reach temperatures that stress shallow roots. There are two easy fixes: site sun-exposed pots where they get afternoon shade, or slip the black pot inside a lighter-coloured outer cover pot. For most British gardens, where genuine heatwaves are still occasional, this isn’t a problem worth worrying about.

A separate concern that does matter: cheap, thin-walled plastic pots become brittle after a year or two of UV exposure and crack. Heavyweight UV-stabilised pots don’t have this problem and last for years. The price difference is small; the durability difference is significant.

What plants do well in plastic pots?

Almost everything that grows in a container at all will do well in a plastic pot. The exceptions are few:

Plants that need exceptional drainage — alpines, succulents, and Mediterranean herbs like rosemary on heavy clay sites — sometimes do better in terracotta because the porous walls let excess water evaporate. But this is solved more reliably by choosing a free-draining compost mix and using crocks at the base.

Permanent specimen plants in show positions — where the look of the pot is part of the display. A statement Japanese maple deserves a glazed ceramic; a hosta on a quiet patio doesn’t.

For everything else — soft fruit, vegetables, hedging in nursery stage, perennials being divided, shrubs being propagated, anything you intend to plant out eventually, anything you’re growing for productivity rather than display — plastic is the right answer.

What sizes do plastic plant pots come in?

The standard range you’ll find at any reputable supplier runs roughly:

• 0.5 litre — for very young seedlings or rooting cuttings
• 1, 2, 3 litre — the everyday workhorse sizes
• 5, 7, 10 litre — for shrubs, small trees, and long-term container plants
• 15, 20, 25 litre — for mature trees, large climbers, and big patio displays
• 30 litre and above — specialist sizes for forestry, fruit trees, and bamboo

Most home gardeners will use 1, 2, 3, 5, and 10 litre pots in regular rotation. We carry these five sizes in our round plant pots collection, all in heavyweight UV-stabilised black plastic with proper factory-moulded drainage holes.

How to make plastic plant pots look better

If your gardening style leans towards the decorative and you’re put off by the utilitarian look of black plastic, the answer is simple: don’t display them. Use plastic pots as the working pot — the one the plant actually grows in — and slip it inside a more attractive outer cover pot or planter. This gives you the practical benefits of plastic (lightness, frost-resistance, drainage, durability) with the appearance of whatever decorative material you prefer.

For permanent outdoor displays in plastic, choose pots in muted colours — slate grey, deep green, or terracotta-effect — rather than glossy black. They photograph better, look more at home in a planted setting, and fade less obviously over time.

Reuse, recycling and end-of-life

A heavyweight plastic pot will give you five to ten growing seasons of regular use if you treat it reasonably — meaning, don’t leave it stacked in full UV sun for months, don’t drop heavy objects on the rim, and don’t overfill the compost so the sides bow outwards.

When pots eventually do need replacing, most UK kerbside recycling collections accept rigid horticultural plastic these days. If yours doesn’t, B&Q and several large garden centres run pot recycling schemes year-round. The black colour traditionally caused sorting problems for older optical recycling lines, but UV-stable black plastic with the appropriate recycling marks is now widely accepted.

In short

A plastic plant pot is a tool, not a decoration. Buy the right size for the plant, look for heavyweight UV-stabilised construction with proper drainage, and they’ll work harder for less money than almost any alternative. They’re not glamorous, but neither is most of gardening — and that’s part of why we like it.