Growing note 08 · Ireland & UK
Grow bags or pots: which suits a small growing space?
“Grow bag” can mean a flat bag of compost or an upright fabric container. They solve different problems. First decide which kind you are comparing.
Three containers, three sets of compromises
| Type | Useful for | Check before choosing |
|---|---|---|
| Flat compost growing bag | Quick setup for suitable crops; broad salad sowings | Limited depth, drainage cuts, watering access and supports |
| Upright fabric sack | Flexible seasonal growing, including potatoes | Stability, usable volume, side drying and the surface underneath |
| Rigid pot | Repeat use, individual plants, a defined footprint | Drainage, durability, weight and actual internal dimensions |
This is a practical comparison of formats, not a product trial. Neither bag nor pot automatically produces a bigger harvest.
Match the root space to the crop
RHS describes growing herbs and salad leaves in flat compost bags, as well as tomatoes in larger growing bags. A shallow bag is not the same as a deep potato sack. Check plant spacing and depth requirements before treating the bag’s picture as a planting plan.
For tomatoes, RHS suggests one plant in a 30–45cm pot or two in a standard growing bag. Commercial bags vary, so check the actual volume and instructions rather than assuming any bag will support that planting. A compact bush plant and a tall cordon also need different support arrangements.
Watering and stability matter more than the label
Whatever the material, use drainage holes and check the compost rather than assuming rain has watered it. Smaller root volumes give you less margin in hot or windy conditions. A saucer catches runoff but should not leave roots permanently waterlogged.
A tall plant needs a support that is stable independently of a thin plastic bag. Position supports without puncturing hidden utilities or damaging balcony waterproofing. Do not fasten anything to a railing without permission. Pots, compost and stored water all contribute to the load.
Think about the second season
A reusable container earns its keep only if you can clean and store it. Inspect fabric seams and rigid pots for damage before reuse. Used growing medium is not automatically useless, but nutrients and structure change and disease history matters; do not present it as identical to fresh compost.
Write down the crop, container format and watering effort. The best fit is often the one you can keep healthy and stable with the time and space you actually have.
A modest kit, if you need it
Compare stated litres, drainage, usable depth and support compatibility. A bag tray or pot saucer may protect a surface but still needs managed drainage.
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Sources & scope
- RHS: vegetables in containers
- RHS: herbs and salad leaves in growing bags
- RHS: tomatoes, varieties, feeding and pollination
Sources consulted 8 November 2026 (Europe/Dublin). This is research-based guidance, not a hands-on trial. Local weather, variety and product instructions matter; equipment types below are not paid endorsements.