Lesson 4
Watering without drowning or drying
Containers dry out faster than ground soil, especially in terracotta, in sun, or in windy positions. In high summer, a 30cm pot of tomatoes can need watering twice daily. The surface may look damp while the root zone is dust. Push your finger 5cm into the compost — if it is dry, water until it runs from the drainage holes.
Underwatering is obvious: wilting, leaf drop, blossom end rot on tomatoes and peppers. Overwatering is subtler and more deadly. Roots sit in saturated compost, oxygen is excluded, and rot sets in. Leaves yellow from the base upward; growth slows; the plant collapses. If the compost smells sour or the pot feels heavy days after watering, you have overdone it.
Saucers and trays are useful in hot weather but dangerous in cool or wet periods. Empty them an hour after watering. Self-watering pots — with a reservoir at the base — work brilliantly for leafy crops and herbs, less well for tomatoes, which prefer a drier root zone to concentrate flavour.
Numbers that matter
- Ideal watering time: early morning, before 9am
- Acceptable second watering in heat: late afternoon, after 5pm
- Reservoir capacity in self-watering pots: typically 2–4 litres, lasts 3–5 days
- Typical daily water loss from a 40cm pot in July: 2–5 litres depending on crop and exposure
Group pots together — they create a humid microclimate and dry out more slowly than isolated containers.