Calibration settings are not universal answers. They are starting points for a controlled test.

A spreader setting only controls how far the aperture opens. The actual application rate depends on material behaviour, walking speed, spread width, pass spacing, slider choice, and the condition of the material on the day.

Use this guide after the spreader has been assembled and checked.

Calibration is the final tuning step. It is not a fix for poor setup, damp material, incorrect slider choice, or inconsistent walking speed.

Check these four things first:

• The spreader is assembled correctly and rolls freely.
• The aperture opens and closes fully.
• The correct slider is fitted.
• The material is dry, free-flowing, and not clumped.

If any of these are wrong, do not calibrate yet. Correct the mechanical or material issue first.

Cresco spreaders use different flow geometry for different material types.

Use for:

• Fertiliser
• Grass seed
• Fine or uniform granular products
• Materials where controlled, measured output matters most

The Summer slider gives finer control over lower and medium output rates. It is the correct starting point for fertiliser and seed calibration.

Use for:

• Free flowing Salt
• Ice melt products
• Larger, irregular particles
• High-volume or poor-flowing winter and summer materials

The Winter slider gives coarse material more room to move and reduces the risk of bridging or intermittent flow.

A setting only means something when the correct slider is fitted.

Using the wrong slider makes the reference setting unreliable. A fine-control slider can restrict salt movement and cause intermittent flow. A winter slider can release fertiliser too heavily and inaccurately for fertiliser applications

Do not try to correct the wrong slider by adjusting the setting. Fit the correct slider first, then calibrate.

When carrying out the below test it is important to test on a suitable area. Repeating tests over the same grass area can cause significant damage to grass. An ideal test area is a hard surface where material can be collected after use

Product labels may give rates in different units.

Use these conversions:

Examples:

• 35 g/m² = 3.5 kg/100m²
• 20 g/m² = 2.0 kg/100m²
• 1.5 kg/100m² = 15 g/m²

The manufacturer’s recommended rate is the target. The Cresco setting is only the starting point used to reach that target.

These settings are approximate first-pass settings. They should be verified by calibration before use.

Assumed conditions: correct slider fitted, dry free-flowing material, steady walking speed of about 5 km/h / 3 mph, measured test area, and pass spacing matched to actual spread width.

The setting scale is not linear. A one-point increase at the top of the scale can release much more material than a one-point increase near the bottom.

Make smaller adjustments at settings 15 and above. If a first test is slightly low at the top end of the scale, do not jump several settings at once. Re-test after one small change.

If the physical gauge on the spreader does not allow a fractional setting shown in the table, use the nearest practical mark and verify by calibration.

Cresco spreaders are designed to spread fertiliser, grass seed, salt, and other winter materials. Each material has its own unique properties so will spread differently.

Fertiliser is usually the most predictable material in a broadcast spreader, but only when it is dry and granular.

Lawn and turf fertilisers commonly fall around 2–4 kg/100m², depending on product, formulation, and season.

Always use the product label as the target. Do not assume all fertilisers use the same rate.

Use the Summer slider.

Uniform fertiliser granules usually flow consistently. First-pass calibration is often close, but adjustment is still normal.

Expect larger variation if:

• the product is damp;
• the granules are unusually fine or dusty;
• the fertiliser contains mixed particle sizes;
• the product has been stored poorly;
• walking speed is inconsistent.

Fertiliser residue can absorb moisture. High-nitrogen products are especially prone to clumping and can accelerate corrosion if left in the hopper or flow path.

After use, always empty the hopper and clean residue from the aperture, slider, impeller area, and fasteners.

Seed is less predictable than fertiliser because seed varieties, coatings, shape, and surface texture vary widely.

Common starting ranges:

• Overseeding: 2–3.5 kg/100m²
• New lawn establishment: 3.5–5 kg/100m²

These are only broad references. Use the seed supplier’s rate for the species, mixture, and purpose.

Use the Summer slider.

Seed may bridge, surge, or flow unevenly if it is light, chaffy, coated, damp, or mixed with debris.

Run the first test carefully. If the output comes in bursts, stop and check the material and aperture before changing the setting.

Some seed mixtures may be difficult to apply evenly because they have irregular shapes. This causing interlocking which can lead to the material bridging in the hopper. To overcome this issue seed should be uniformly mixed with a sharp dry flowable sand enabling uniform application of that particular seed mixture.

Do not assume a fertiliser setting transfers to seed, even if the target rate looks similar. Seed can have a different bulk density and completely different flow behaviour.

Re-calibrate when changing seed type, or rate.

Salt calibration matters because under-application may be ineffective and over-application wastes material, increases corrosion risk, and can damage nearby vegetation or surfaces.

For private paths, driveways, and private car parks:

• Precautionary treatment before frost or light ice: 10–15 g/m² / 1.0–1.5 kg/100m²
• Existing ice or compacted snow: 20–30 g/m² / 2.0–3.0 kg/100m²

For professional, commercial, council, or highway use, follow the relevant site plan, risk assessment, treatment matrix, or local authority specification. Do not use this guide as the governing standard for public highway treatment.

Actual salt need depends on surface temperature, forecast, moisture, traffic, residual salt, material type, and whether treatment is precautionary or reactive.

Use the Winter slider.

Dry, flowable salt with a consistent particle size can calibrate reliably. Damp or clumped salt will not.

If salt flow stops and starts, do not immediately open the aperture. First check for damp material, lumps, bridging, or blockage around the slider. Good quality salt is important to achieve consistent material flow.

Dry bagged white marine salt is recommended.

Salt is corrosive.

Rinsing without drying is not enough. Standing water can still promote corrosion.

The setting controls output rate. It does not set the working width.

Spread width is mainly affected by:

• particle size and density;
• impeller design and speed;
• walking speed;
• wind;
• material condition;

A spreader can be correctly calibrated for output rate and still leave stripes if pass spacing is wrong.

When switching between fertiliser, seed, and salt, check both:

• the application rate setting;
• the actual spread width and pass spacing.

Salt often travels farther than fine fertiliser at the same walking speed. Fine fertiliser may require closer passes.

Recalibrate when:

• changing material type;
• changing product brand or formulation;
• changing from fertiliser to seed or salt;
• changing slider;
• using damp, stored, or visibly different material;
• changing target rate;
• changing walking speed
• results look uneven or material use does not match the expected rate.

Do not recalibrate repeatedly once the result is close, even, and repeatable. Over-adjustment often makes results worse.