Bonsai Watering Schedule Calculator

Bonsai trees need more frequent watering than regular potted plants because their pots are small and shallow. The soil dries out fast, and bonsai are unforgiving at both ends: too much water rots the roots, too little kills the tree in a single hot afternoon.

How often you water depends on five key factors:

1. Species type

• Tropical species (ficus, jade, schefflera): Like consistently moist soil. Typically water every 1–2 days in summer, every 2–4 days in winter.
• Subtropical species (Chinese elm, serissa, olive): Moderate moisture. Typically every 2–3 days in summer, every 3–5 days in winter.
• Temperate species (juniper, maple, pine): Tolerate drying between waterings. Typically every 2–4 days in summer, less in winter dormancy.

2. Pot material

• Terracotta clay: Porous, water evaporates through the walls. Dries fastest.
• Mica / unglazed ceramic: Similar to terracotta but slightly slower.
• Glazed ceramic: Non-porous, retains moisture longer.
• Plastic: Slowest drying, retains water well.

3. Pot size

Smaller pots hold less soil and dry out much faster. A tiny 4-inch pot may need watering every day in summer. A large 12-inch pot may only need water every 3–4 days.

4. Season

In summer, heat and active growth increase water uptake dramatically. In winter, trees slow down and the soil dries far more slowly. Deciduous species that have dropped their leaves are the extreme case: with no foliage transpiring, they use a fraction of what they did in July.

5. Climate / humidity

Dry desert climates or air-conditioned rooms dry out soil much faster. Humid coastal climates or greenhouses retain soil moisture longer.

The fingertip test: Push your finger about 1 cm (1/2 inch) into the soil. Dry or barely moist, water now. Still wet, wait another day. Never let bonsai soil dry out completely, and never keep it waterlogged.

Watering technique: Water slowly and thoroughly until water runs from the drainage holes. This ensures the entire root mass gets moisture. Misting the leaves does NOT replace root watering.