Watering a Container Garden

How portable containers dry, how to test the soil, and how to build a watering rhythm that fits the pot size.

A container holds only a small reservoir of moisture, so the watering rhythm depends on pot size, plant size, and how much air moves around the surface. Small pots and hanging baskets dry fastest, while barrels hold moisture longest.

The reliable test is the finger test: push a finger about 2 cm into the soil. If it feels dry at that depth, water until a little runs out of the drainage hole. If it feels damp, wait and check again later.

In warm weather, small pots and baskets may need checking twice a day. Tubs and boxes usually need checking once a day. Barrels can go two or three days between checks in mild conditions.

Water in the morning where possible so the leaves dry before evening. Never let a pot sit in a full saucer of standing water, because roots need air as well as moisture.

Grouping pots together slows drying, because the group creates a slightly more humid pocket of air. Moving pots out of direct sun during a heat spell does the same.

If you are away for a few days, shift pots into shade, group them, and rely on the largest containers you have. A barrel may hold moisture for three to five days in warm weather; a small tin can dry in under a day.

• Finger test at 2 cm depth before every watering.
• Water until it runs from the drainage hole.
• Morning watering keeps leaves dry overnight.
• Group pots to slow drying.
• Move pots to shade during heat spells.

Further reading

• Pots, Tubs, Barrels: Choosing Containers
• Easiest Edible Plants for Pots