Growing in containers
Quick answer. A container is a closed root zone with a small volume, no reserve and no buffering. That means three things: water frequently, feed little and often rather than heavily and rarely, and water thoroughly enough that some drains from the base — because in a container, salts accumulate where there is nowhere for them to go.
Why containers behave differently
Open soil has depth to draw on, a large volume to buffer any single application, and rainfall or irrigation moving through it. A container has none of that. Its entire nutrient reserve is what you put in, its entire water reserve is a few litres, and everything applied stays in that volume until it is taken up or flushed out.
The parallel to FAO's account of sandy soils is close: low storage capacity for mineral nutrients, low water-holding capacity, and consequently a need for frequent, smaller applications rather than infrequent large ones. A container is that principle intensified.
Salt accumulation — the specifically container problem
Every irrigation adds whatever salts the water carries, and every fertiliser application adds more. Water taken up or evaporated leaves them behind. Over a season a container can accumulate a salt concentration well above that of the water going in, and the visible result — leaf-margin scorch, stunting, poor growth despite regular feeding — looks like a deficiency and is the opposite.
The remedy is leaching: watering thoroughly enough that water drains freely from the base and carries salts out with it. A container with no drainage hole cannot do this and will accumulate salts indefinitely. Given that Kuwaiti irrigation water is frequently the source of the salts, this is not an occasional maintenance task here.
Which crops suit containers
Good: radish (shallow, fast), lettuce and rocket, the culinary herbs, peppers, and bush beans. Workable with depth: carrot and beetroot, where depth is the limiting factor rather than width, and potato in a deep container or sack. Difficult: cauliflower and cabbage, which need a large leaf frame and are sensitive to any check.
Containers also solve two specific problems well — they contain mint's runners, and they let rosemary and thyme be given the sharp drainage they need without rebuilding a bed.
Do not group plants with different water needs in one container. The clearest case is the culinary herbs: mint and basil want consistent moisture while rosemary and thyme are harmed by it. A single pot containing all four cannot be watered correctly for any of them. Leaf-margin scorch in a container is more often salt accumulation than deficiency — leach before you feed. A visual symptom alone is not a confirmed diagnosis.
Sources
FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapter 4 (nutrient storage capacity and water-holding capacity by texture), Chapter 5 (arid soils: soluble salts), Chapters 3 and 7. Accessed 27 August 2026. No container volume, rate or irrigation quantity is stated.
Last reviewed 27 August 2026