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Garden Calculators

Plan your garden with precision: fertilising, watering, plant density and bed area calculators.

Gardening — calculators and converters

A well-planned garden rewards precision as much as patience. Garden calculators on Liczbnik.pl help you work out planting density, fertiliser doses, watering schedules and the volume of soil needed for raised beds — all accurately and instantly. The garden area and bed calculator lets you measure your plot, compute the area of each zone and determine how many plants will fit. Planting density depends on the species — tomatoes every 50–60 cm (3–4 plants/m²), lettuce every 25 cm (9–16 plants/m²), carrots every 5 cm in the row (over 80 plants/m²). Knowing your available space, the calculator instantly tells you how many seedlings or seed packets to buy. Fertilising is the key to a healthy harvest, but excess nitrogen harms plants and the environment. The fertiliser calculator works out the dose based on soil type, pH, crop species and desired yield. A lawn needs 2–4 g of pure nitrogen per m² per month during the growing season — about 20–40 g of a 10% N compound fertiliser. For 100 m² of lawn that is 2–4 kg of product per month. Watering is the largest ongoing use of garden water, especially in summer. The watering calculator estimates daily water requirements by plant species, air temperature and soil type. Sandy soil needs watering more frequently than clay. Leafy vegetables (lettuce, spinach) need 2–3 l/m²/day at 25°C, while fruit trees require 20–60 litres per week. Soil for raised beds and planters must be calculated precisely. The soil volume calculator converts bed dimensions (length × width × depth) into litres or cubic metres, making it easy to buy the right amount of compost or peat. A 2 × 1 × 0.3 m box needs 0.6 m³, or about 600 litres of growing medium. All garden calculators are free and work on any device.

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Frequently asked questions about gardening

How to calculate garden area?

Rectangle area = length × width. For irregular shapes, divide into rectangles or triangles.

How much fertiliser per m² of lawn?

A lawn needs about 2–4 g nitrogen/m²/month during the growing season (April–September).

How many plants per m²?

Planting density depends on species: tomatoes 3–4/m², lettuce 9–16/m², carrots 80–100/m².

On hot days, a garden needs about 10–20 l/m²/week. Vegetables need 2–3× more than a lawn.

Test soil pH with a pharmacy test kit or electric meter. Optimal pH for most plants: 6–7.

Sowing time depends on the plant and climate. Tomatoes: March under cover; carrots: April outdoors.

Acidic soil (pH < 6) is corrected with liming; alkaline soil (pH > 7) with peat or iron sulphate.

Volume = length × width × height (metres). E.g. 2 m × 1 m × 0.3 m = 0.6 m³ of soil.

Usage = concentration [ml/l] × water volume [l]. E.g. 5 ml/l × 10 l = 50 ml of product.

Spring (March–April) — nitrogen and phosphorus; summer (June) — nitrogen; autumn (October) — potassium and phosphorus.