Preparing a vegetable bed
Quick answer. Loosen to a depth that suits the deepest-rooting crop you intend to grow, remove stones, incorporate well-decomposed organic matter, and level the surface. For root crops the physical work is the decisive step — a stony or lumpy bed produces forked and distorted roots that no later application can correct.
Depth is set by the crop, not by habit
A bed for lettuce and rocket does not need the depth a bed for carrot does. Preparing every bed to the same depth either wastes effort or limits the crop. Decide the crop first.
Onion and garlic sit at the other extreme: both are shallow-rooted with sparse root systems, and depth of preparation matters far less to them than looseness near the surface and freedom from weed competition.
Well-decomposed organic matter, and why the qualifier matters
Organic matter raises water-holding capacity and cation exchange capacity — FAO states that soils rich in organic matter have a higher CEC than soils low in it, and puts the CEC of sandy soils below 10 cmol/kg against more than 30 for clay soils. On a sandy Kuwaiti soil, organic matter is one of the few levers available for holding both water and nutrients in the root zone.
But it must be decomposed. Fresh or lumpy material causes forking in carrot and radish, and material with a wide carbon-to-nitrogen ratio temporarily immobilises nitrogen as it breaks down — the bed appears nitrogen-deficient for reasons that have nothing to do with how much nitrogen you applied. Ideally, apply organic matter to the previous crop rather than immediately before a root crop.
Levelling
An uneven bed waters unevenly, and uneven water is the root cause of splitting in root crops, blossom-end rot in fruiting crops and inconsistent germination in everything. Levelling looks cosmetic and is not.
Food safety
Many crops in this library are eaten raw and in direct contact with the soil — carrot, radish, beetroot, lettuce, rocket and the herbs. Do not incorporate raw manure into beds destined for those crops. This is a food-safety rule, not a horticultural preference.
Do not apply fertiliser to a bed on the assumption that it is needed. FAO's list of arid-soil problems includes frequent iron and zinc deficiencies caused by fixation under alkaline reaction, occasional excess of soluble salts, adsorbed sodium and boron, and low available nitrogen. Those are opposite problems requiring opposite responses, and only analysis distinguishes them. Test before you build a programme. A visual symptom alone is not a confirmed diagnosis.
Sources
FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapter 4 (CEC ranges by texture; organic matter and CEC), Chapter 5 (special problems of arid soils; C:N ratios), Chapters 3 and 7. Accessed 27 August 2026. No depth, rate or quantity is stated.
Last reviewed 27 August 2026