How often to water tomato

The interval

Tomatoes are watered more often than almost any other plant in this journal. A fruiting plant in a pot in hot weather can need water every day, and twice a day at the height of summer, which is why the 2 days in the schedule is the longest a potted plant should wait in warm weather. In the cool part of the year, in spring seedlings, a cool greenhouse or the last weeks of the crop, about every 7 days is enough. The warm part is late spring and summer, roughly May to September in the northern hemisphere and November to March in the southern. It is not a winter plant.

Judge by touch, weight and the plant itself. Push a finger 3 cm into the compost: it should feel damp and never dry. Lift the pot, since a full pot of moist compost is heavy and a dry one is light. The Royal Horticultural Society says plants in containers dry out quickly and may need watering daily in hot weather, and that curling leaves can be a sign a tomato plant is short of water.

The method is even watering at the base. The RHS advises keeping the soil or compost evenly moist, and suggests sinking a 15 cm pot beside the plant and watering into it so that moisture reaches the roots directly. A pot at least 30 cm across and deep holds enough to even out the swings.

Uneven watering is the cause of most tomato trouble. The RHS and NC State Extension both link splitting and blossom end rot to uneven moisture, and NC State Extension says cracking comes from uneven watering or from the weather. Moisture that sits around the neck of the plant can lead to rotting, and the RHS suggests sinking a small pot beside the plant to avoid it.

What is particular to tomatoes is that the penalty for uneven watering is paid by the fruit. A dry spell followed by a deep soak is when fruit splits, so be steady, not generous.

Related guides

How to tell whether a plant actually needs water

The finger, the weight, the leaf and the pot. Four ways to read a plant's thirst, and what overwatering actually is.

Rescuing an overwatered plant

How to tell overwatering from underwatering, how much root damage is recoverable, and the exact rescue steps once compost has stayed wet too long.

Watering through a southern winter

Winter in the southern hemisphere runs June to August, and houseplants drink far less then. How to read the soil, and why overwatering is the bigger risk.