Free herb garden water calculator. Enter herb plants to find the daily and weekly water your herb garden needs in millilitres.
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Enter the number of herb plants in your garden. The calculator uses a planning baseline of 150 millilitres per plant per day and multiplies it by 7 for the weekly total. Use the per herb guidance below to adjust: moisture loving herbs such as basil and mint need water more often, while drought tolerant herbs such as rosemary and thyme need water less often. Always check the soil with the finger test before watering again.
This herb garden water calculator uses 150 millilitres per plant per day as a simple planning baseline, so 6 plants need 900 millilitres per day and 6,300 millilitres per week. That baseline is a starting point for a herb garden watering guide, not a fixed rule for every plant, because pot size, soil, sun and season change how much water do herbs need in practice. Treat the result as an estimate and adjust it with the finger test described below.
Herbs fall into two watering groups, and grouping them helps a herb watering schedule work. Moisture loving herbs include basil, mint, parsley, cilantro and chives, which like soil that stays lightly moist. Drought tolerant herbs include rosemary, thyme, oregano and sage, which prefer soil that dries out between waterings. Mint should usually have its own pot, because it spreads fast and drinks more than its neighbours.
Basil watering frequency is the highest of the common herbs: basil often needs water every 1 to 2 days in warm weather, and daily in a small pot in summer heat. Mint watering schedule is similar, every 2 to 3 days, with soil kept consistently moist. Rosemary watering frequency is much lower, about every 7 to 10 days outdoors, with a deep soak and then a dry period, which is why rosemary rots quickly in constantly wet soil.
Watering herbs in pots needs more attention than watering herbs in the ground, because pots dry out faster and hold less soil. Watering herbs in containers in summer may mean watering every 1 to 2 days, and always water until a little drains from the bottom, then empty the saucer so roots do not sit in water. Terracotta pots dry faster than plastic pots, so check terracotta daily in hot weather. Indoor herb watering follows the same rule: water when the top 2 to 3 centimetres of soil feels dry.
Soil type changes the schedule. Sandy soil drains fast and may need water every 1 to 2 days, loam holds moisture and suits every 3 to 4 days, and clay holds water longest at every 4 to 7 days with a slow deep soak. How often to water herbs outside in summer depends on sun too: hot sunny spots with 6 or more hours of sun need water every 1 to 2 days, while cool shady spots need water every 3 to 4 days. In winter, water requirements for herbs fall sharply, so water less often and let the soil dry more between waterings.
The best time to water herbs is early in the morning, when water soaks in before the heat of the day and leaves dry quickly, which lowers disease risk. Water around the base of the herb, never all over the leaves, and water deeply so moisture reaches the roots instead of only wetting the surface. The finger test is the simplest check: push a finger 2 to 3 centimetres into the soil, and water only if it feels dry at that depth.
For 6 herb plants, the calculator gives 900 millilitres per day and 6,300 millilitres per week, which is about 6.3 litres per week. If those 6 plants are mostly basil and mint in pots in summer, water a little more often and in smaller amounts; if they are mostly rosemary and thyme in the ground, water less often and more deeply. Split the daily amount across the plants, and skip a watering when rain has already soaked the bed.
Can you overwater herbs? Yes, and it is the most common cause of herb deaths in pots. Overwatering signs are yellowing leaves, wilting despite moist soil, and soft stems or root rot. Underwatering signs are dry crispy leaf edges, drooping leaves that recover quickly after watering, and soil pulling away from the pot sides. If a plant is overwatered, stop watering, let the soil dry, improve drainage, and only resume when the top soil is dry.
As a planning baseline, this calculator allows 150 millilitres per herb plant per day, so 6 plants need about 900 millilitres per day. Real needs vary by herb: basil and mint need more, rosemary and thyme need less, and pots in summer need more than beds in cool weather.
Most herbs need water every 2 to 3 days in normal conditions, but the range is wide: basil every 1 to 2 days in warm weather, mint every 2 to 3 days, parsley every 3 to 5 days, and rosemary every 7 to 10 days. Water when the top 2 to 3 centimetres of soil feels dry, not on a fixed calendar alone.
Outside in summer, moisture loving potted herbs may need water once or twice a day in heat, while herbs in the ground usually need water every 1 to 2 days for basil and mint and every 5 to 7 days for rosemary and thyme. Morning watering and mulching help the soil hold moisture longer.
Use the finger test: push a finger 2 to 3 centimetres into the soil. If it feels dry at that depth, water deeply; if it still feels moist, wait. A light pot also signals dry soil, while a heavy pot usually means the soil is still wet.
Yes. Overwatering causes yellowing leaves, wilting in wet soil, and root rot, especially for rosemary, thyme and sage. Always use pots with drainage holes, empty saucers after watering, and let drought tolerant herbs dry out between waterings.
Yes, water herbs less in winter because growth slows and evaporation falls. Indoor herbs may need water only every 4 to 7 days in winter, and outdoor herbs need even less when it is cool and rainy. Keep checking the soil rather than following the summer schedule.
A well drained potting mix suits most herbs, with compost mixed in for moisture loving herbs and extra grit or perlite for rosemary, thyme and sage. Soil should hold moisture without staying soggy, because soggy soil is the main cause of root rot in pots.
Early morning is the best time to water herbs. Water soaks to the roots before the heat of the day, leaves dry quickly, and less water is lost to evaporation than at midday. Avoid watering late in the evening in cool weather, when wet leaves stay damp overnight.
Yes, but only group herbs with similar water needs: basil, mint (best alone), parsley and cilantro together, or rosemary, thyme, oregano and sage together. Mixing a thirsty herb with a drought tolerant herb in one pot usually leaves one of them unhappy.