Fabric, Air-Pot or Plastic Pots? How to Choose (and What Size)
A pot is more than a container: its shape and walls change how fast the growing medium dries out and how the roots grow. This guide compares Air-Pots, fabric pots and plain plastic pots, and helps you pick the size.
The three kinds
| Pot | How it works | Watch out for |
|---|---|---|
| Air-Pots | Holes in the wall air-prune the root tips, so roots branch instead of circling the pot | Dry out faster than standard pots, especially if you hand water |
| Fabric pots | Porous fabric drains well, airs the root zone and air-prunes the roots; folds flat, with handles | Dry out faster too; need a saucer or tray |
| Plastic pots | Solid walls with drainage holes; the cheapest and easiest to keep watered | Roots can circle the wall; easier to overwater |
Air-pruning is the big idea behind Air-Pots and fabric pots: when a root tip reaches the air at the wall it stops, and the plant grows more fine feeder roots instead. RootMASS fabric pots can also go in recirculating systems, where the fabric acts as a filter between the medium and the reservoir.
Air-Pot sizes
| Size | Diameter x height | Use |
|---|---|---|
| 1 L | 10 x 14.5 cm | Rooted seedlings and cuttings, before potting on |
| 3 L | 15 x 23.5 cm | Intensive hydro and coco systems, plants up to 60 cm |
| 5 L | – | Medium-sized plants |
| 9 L | 23 x 30 cm | The most popular size in soil; mother plants up to 100 cm |
| 12.5 L | – | Larger plants |
| 20 L | 31 x 31.5 cm | Very large plants up to 200 cm, outdoors or as long-term mother pots |
| 38 L | – | Big plants that need a lot of room |
Fabric and plastic sizes
| Pot | Sizes | Watering | Notes |
|---|---|---|---|
| RootMASS Fabric Plant Pots | 1, 2, 3.8, 12, 16, 20, 25, 30 and 39 L | By hand, on drippers or in a recirculating system | Foldable, with handles |
| Autopot FlexiPot | 20 L, 35 L and 50 L | Self-watering: gravity-fed, no timer or electricity | Soil, coco or hydro media. Complete systems come with a tank; a Module Only adds a pot to an existing Autopot system |
Both air-prune the roots. The difference is the watering: a plain fabric pot dries out fast, so it needs watering often, while on a FlexiPot the AQUAvalve refills the tray under the pot from the tank each time it runs dry. For tanks, system sizes and set-up, see our Autopot guide.
- Round plastic pots: 10 L (28.3 x 22 cm), 15 L (31.8 x 26 cm), 20 L (35.8 x 29 cm), 25 L (35.8 x 33 cm) and 30 L with handles.
- 11 L square pots: 25 cm square by 26 cm high - square pots fit closer together in a tent.
- Square-to-round pots: 1, 2, 3 and 5.5 L, for taking cuttings and seedlings through to their final pot.
- For hydroponic systems: heavy-duty net pots (80, 140 and 200 mm) and mesh propagation pots.
Saucers and trays to match
Our Round Saucers come in 30, 35, 40 and 45 cm; our plant pot sizes guide shows which saucer or tray takes which pot. Fabric pots drain through the sides as well as the base, the RootMASS page says, and our soil and coco bundles, such as the 4-Pot Soil & Nutrient Bundle, stand each 12 L fabric pot on a 35 cm saucer. Empty the saucer or tray after watering: our root rot guide says never to leave a pot standing in run-off.
Which should I choose?
- Hand watering in soil: plastic or 9 L Air-Pots. Plastic stays wet longer, which is easier to manage; Air-Pots grow a better root ball but need watering more often.
- Coco on drippers: Air-Pots or fabric pots - coco likes frequent feeds and lots of air, and the faster drying stops it from staying soggy. See our coco guide and dripper systems guide.
- Automatic watering: the Autopot FlexiPot puts a fabric pot on an Autopot tray. See the Autopot guide.
- Cuttings and seedlings: 1 L Air-Pots or small square-to-round pots, then pot on. See propagators and cuttings.
Quick answers
Do Air-Pots need watering more often?
Yes. The holes that air-prune the roots also let the medium dry faster, so expect to water more often than in a plastic pot of the same size.
Can I reuse fabric pots?
Yes - empty, wash and dry them. They fold flat for storage.
What goes under fabric and Air-Pots?
A saucer or tray to catch run-off: see our trays and saucers.
Which fabric pot size for a 1.2 m tent?
As a rule of thumb, our grow tent size guide gives plants in medium pots (8-12 litres) about 40 x 40 cm of floor each, and puts two to four plants in larger pots (15-25 litres) on each square metre. So in a 120 x 120 cm tent, the RootMASS 12 L pot suits more, smaller plants, and 16 or 20 L fewer, bigger ones. Our 8-Pot Soil & Nutrient Bundle, which our grow tent setup guide pairs with the 1.2 m tent kit, comes with eight 12 L fabric pots and saucers. On an Autopot, the smallest FlexiPot we sell is 20 L: the FlexiPot 4-Pot System has four 20 L pots on one 47 L tank.
How is pot size measured?
In litres for how much it holds, and in centimetres across the top: on the Round Pots page, 10 L (28.3 x 22 cm) means 28.3 cm across the top and 22 cm high. Our plant pot sizes guide shows how to measure a pot and lists our pots by the litre with the measurements their pages give.
Do you sell EasyFeed fabric pots?
No. Any fabric pot works on the same idea: a porous wall that drains and air-prunes the roots. But we cannot tell you how EasyFeed fabric or sizes compare, or whether our pots fit a system from another maker. The fabric pot ranges we sell are RootMASS and, for self-watering, the Autopot FlexiPot, in the table above.
More Growers' Guides
Not sure what you need? Call the shop on 0117 971 3000 or pop in to the Bristol store and we'll help you pick.