Free garden watering calculator. Enter how many plants you are watering to find the water in litres and the 10 litre cans you need.
Your results will appear here.
Enter your values and press Calculate.
Enter the number of plants. This calculator allows 0.5 litres of water per plant, then divides litres by 10 for the watering cans.
How much water per plant in litres depends on the plant, the soil, and the season, so the 0.5 litres per plant in this garden watering calculator is a simple planning estimate for an average garden plant, not a rule for every species. Competitor guides quote much wider ranges: a mature tomato needs about 4 to 6 litres per week in warm weather and up to 8 litres in hot conditions, peppers need about 0.5 to 1 gallon every 2 to 3 days, and leafy greens need about 0.25 to 0.5 gallons every 1 to 2 days. Use the calculator result as your starting total, then water more for large, thirsty, or fruiting plants and vegetables and less for small, drought tolerant, or newly planted ones. Always check the soil before watering again, since a fixed schedule waters some plants too much and others too little.
Garden watering can fills follow directly from the plant count. For 10 plants, this calculator gives 5.0 litres of water and 0.5 cans of 10 litres, so one part filled can covers the round. For 20 plants, it gives 10.0 litres and 1.0 can, exactly one full 10 litre watering can. For 50 plants, it gives 25.0 litres and 2.5 cans. For 100 plants, it gives 50.0 litres and 5.0 cans. Round fractional can counts up to whole fills when you carry water, since 0.5 cans means one trip with a half full can and 2.5 cans means three trips with the last can half full.
Garden watering litres per week are often quoted as 1 inch (2.5 cm) of water per week over the planted area. The conversion is 0.62 gallons per square foot per inch of water, so a 100 square foot bed at 1 inch per week needs about 62 gallons, or about 235 litres. A 10 square metre bed at 1 inch per week needs roughly 250 litres. To convert inches of water to gallons per square foot, multiply area in square feet by inches by 0.623. The plant count method in this calculator is simpler for mixed beds, while the area method suits lawns and uniform beds, and both are planning estimates, not measured soil moisture.
How much water for container plants versus garden plants differs sharply, because pots dry out faster than open ground. Container plants in summer often need daily checks, while in ground plants can go several days between deep waterings. How much water per pot size guides the amount per pot: a 1 litre pot needs about 100 to 150 ml, a 2 to 4 litre pot about 200 to 600 ml, a 5 to 7 litre pot about 500 to 1050 ml, and a 10 to 15 litre pot about 1 to 2.25 litres. For pots, water until a little drains from the base, then empty the saucer so roots do not sit in water. For the plant count total in this calculator, treat large containers as more than one average plant.
A watering schedule calculator that ignores soil type will mislead you. Sandy soil drains fast, so water every 2 to 3 days in smaller amounts. Loam holds moisture well, so water every 3 to 4 days with a deep soak. Clay holds water longest, so water every 4 to 7 days slowly so it soaks in rather than running off. Raised bed mix behaves like a light loam and needs water every 2 to 3 days in warm weather. Mulch reduces how often you need to water, because a mulch layer slows evaporation and keeps soil cooler, so mulched beds often need one fewer watering per week than bare beds.
Seedlings versus mature plants need very different amounts. A seedling with two true leaves may need only a tablespoon or two of water daily, while a mature tomato in peak summer needs litres per week. Newly planted shrubs and trees need frequent watering in their first season, then less as roots establish. Established trees and shrubs often need no weekly watering at all in normal rainfall, except in drought. When you use this calculator for a mixed bed, count seedlings as a fraction of a plant and large mature plants as more than one, or split the bed into two calculations.
Deep watering versus shallow watering garden advice is consistent across competitors: water deeply a few times a week rather than lightly every day, so roots grow down instead of staying near the surface. Divide the weekly total by 2 or 3 sessions for most beds. Subtract rainfall from the weekly total: about 0.1 inch of rain saves roughly 0.6 gallons per plant on a tomato sized footprint, and heavy rain can replace a whole session. In hot weather, add water for evaporation, and in cool or cloudy weather, skip a session and check the soil first. Water in the morning or evening, not in midday heat, so less water evaporates before it reaches the roots.
What size watering can should you use? A 10 litre watering can suits a large garden, while a 1 to 2 litre can suits indoor plants. A fine rose suits seedlings and soft leaves, and a coarse rose suits established beds. How do you prevent overwatering with a watering can? Water slowly, check the soil first, and stop when the top few centimetres are damp, not muddy. Signs of overwatering are yellow leaves, soft stems, and constantly wet soil, while signs of underwatering are wilting, dry crisp leaf edges, and soil pulling away from the pot. You can also use a watering can for fertilizing plants by mixing liquid feed at the label rate, then clean the can after feeding and store it empty and dry.
About 0.5 litres per plant in this calculator as a planning estimate. Thirsty plants like tomatoes need more, about 4 to 6 litres per week in warm weather, and small or drought tolerant plants need less.
One full 10 litre watering can. Twenty plants at 0.5 litres each need 10.0 litres, which is exactly 1.0 can.
Most beds do best watered deeply 2 or 3 times per week, not lightly every day. Sandy soil needs water every 2 to 3 days, loam every 3 to 4 days, and clay every 4 to 7 days.
Yes, morning or evening is better than midday. Less water evaporates, leaves dry before night in the morning slot, and roots get time to absorb the water.
About 4 to 6 litres per week in warm weather in open ground, up to 8 litres in hot conditions, and about 2 to 3 litres per day in containers in summer.
Yes. Mulch slows evaporation and keeps soil cooler, so mulched beds often need one fewer watering per week than bare beds.
Container plants dry out faster and often need daily checks in summer, while in ground plants can go several days between deep waterings. Water pots until a little drains, then empty the saucer.
A 10 litre watering can for a large garden, a 5 litre can for a medium garden, and a 1 to 2 litre can for indoor plants. Use a fine rose for seedlings and a coarse rose for established beds.
Check the soil first, water slowly, and stop when the top few centimetres are damp. Yellow leaves and constantly wet soil are signs you are watering too much.
Yes. Deep watering a few times a week encourages deep roots, while daily shallow watering keeps roots near the surface where they dry out faster.
Balance your compost pile - hit the ideal 30:1 carbon-to-nitrogen ratio.
Find how many plants fit your garden bed, in square or triangular layouts, from bed size and plant spacing.
How much soil for a raised bed? Volume, bag counts, mix ratios, weight and cost in one tool.