Garden Treatment Dilution Calculator
Getting a weedkiller or feed too concentrated can scorch plants, while too weak a mix wastes a trip round the garden with little effect. Pick your dilution ratio and container size below to see exactly how much concentrate and water to combine.
Work out your garden treatment mix
Pick the dilution ratio and your sprayer or container size to see how much concentrate and water to use.
To fill a 5L container at 1:100, use:
50ml concentrate
Topped up with 4.95L water (4950ml) to fill the container.
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Frequently asked questions
Does this calculator work for any weedkiller or feed?
This calculator is a general mixing helper for common ratios like 1:50, 1:100 and 1:200. You should always follow the specific product's label instructions, since the correct dilution ratio varies by brand and by what you're treating.
What does a ratio like 1:100 mean?
A ratio of 1:100 means one part concentrate mixed with 100 parts water, so the concentrate makes up a small fraction of the total mixed volume in the sprayer or container.
Can I mix more than I need and store the leftover?
It's best to mix only what you'll use in one session, since many diluted garden treatments lose effectiveness or should not be stored once mixed with water, according to most product labels.
Why does the water amount not add up to a round number?
The water volume is whatever's left in the container once the concentrate is added, so it will often be a slightly uneven number rather than a round figure — that's expected and fine to use.
How this calculator works
The calculator takes as input the area of the garden space you’re treating (in square metres) and the desired concentration percentage of your chosen product. Most liquid garden products are supplied with a recommended dilution rate, often expressed as a percentage – for example, 1 litre concentrate mixed with 9 litres water. The calculator then performs a simple division to determine the volume of concentrate needed. It assumes you’re applying a uniform solution across the entire treated area.
Dilution Rates for Common UK Garden Products
- **Liquid Weedkillers:** Many professional weedkillers require a dilution of 1 part concentrate to 5-10 parts water, depending on the weeds being targeted and the size of the area. Smaller lawns might need a lower concentration than larger garden beds.
- **Fertilizers:** Slow-release fertilizers typically require more concentrated mixing initially, followed by gradual watering down. Always check product labels for specific instructions; some may benefit from a higher initial dose.
- **Moss Treatments:** Moss treatments often use high concentrations of potassium salts and require careful application to avoid damaging surrounding plants. Dilution rates vary significantly – always start with the lowest recommended level and increase if needed.
- **Fungicides:** Similar to weedkillers, fungicide dilution depends on the severity of the fungal infection. Broad-spectrum fungicides usually need a higher concentration for initial treatment.
- **General Rule:** Always err on the side of caution when diluting concentrated products; it’s better to slightly under-dilute than over-dilute and risk damaging your plants.
Worked example: Treating a Small Lawn
Let's say you need to treat a lawn measuring 40m² with a weedkiller that has a recommended concentration of 25%. Using the calculator, you’d input 40m² and 25% into the fields. The calculator will then output 1 litre of concentrate mixed with 9 litres of water – resulting in a total volume of 10 litres applied to your lawn. This would cost approximately £12-£20 depending on the brand and size of the concentrate bottle (typically 1L bottles are around £15-£30).
Remember, this is just one example. Always read the product label carefully for specific instructions tailored to that particular garden treatment. Factors like rainfall and sunlight exposure can also influence how quickly a product degrades and needs reapplication; monitor your lawn regularly.
More questions answered
What units should I use when entering the area?
Please enter the area in square metres (m²). This is the most common unit used for measuring garden spaces and ensures accurate calculations. Converting from other units, such as feet squared, will affect the accuracy of the result.
What if my product doesn’t have a percentage listed?
If the product label only provides a volume per area (e.g., 1 litre per 100m²), you'll need to estimate the concentration based on the product's instructions and your own experience. Start with a lower dilution rate and adjust as needed.
Can I use this calculator for granular fertilizers?
While you can input the area, granular fertilizers are typically applied at a fixed rate per square metre. This calculator is most effective for liquid products where dilution is required. Consult the fertilizer's packaging for application rates.
What happens if it rains soon after I apply the treatment?
Rain will wash away diluted treatments, reducing their effectiveness. Consider applying in the early morning or evening to minimize this effect, and re-apply if necessary – always checking product instructions.
How do I account for uneven ground?
The calculator assumes a relatively uniform application. If your lawn has significant dips or bumps, you may need to increase the concentration slightly in those areas to ensure even coverage.
What if I want to treat a border rather than a lawn?
Simply measure the length and width of your border in metres and input this into the calculator. The result will be the volume of concentrate required for that area.
Is this calculator suitable for large commercial gardens?
For very large areas, it's recommended to use a more sophisticated application method or consult with a professional groundskeeper to determine the appropriate concentration and coverage rate.
What if I accidentally add too much concentrate?
Immediately flush the treated area thoroughly with water. Monitor the plants for signs of damage – if symptoms persist, contact your local garden centre or agricultural advisor for advice.
How does this calculator compare to reading the product label directly?
The calculator provides a quick and easy way to determine the concentrate volume; however, always read and follow the manufacturer’s instructions on the product label as they may contain specific recommendations based on environmental conditions or plant types.
What if I'm using a different brand of weedkiller?
The calculator is designed for products with a standard concentration percentage. If you are using an unusual product, always start with the lowest recommended dilution rate and carefully monitor your plants for any adverse reactions before applying over a larger area.