Calculate solution volume, coverage area, and feeding duration based on fertilizer amount.
Enter amount in Tablespoons (tbsp). (Note: 1 lb box ≈ 32 tbsp).
Standard (1 tbsp per Gallon)
Weak / Seedlings (0.5 tbsp per Gallon)
Heavy Feeder (2 tbsp per Gallon)
Custom Ratio
Gallons Per Minute (Default: 2.5)
Total Solution Produced– gal
Est. Coverage Area– sq ft
Time to Empty Feeder– min
*Calculations assume consistent water pressure and that the feeder siphon is functioning correctly. Coverage assumes approximately 1 gallon per 10 sq. ft. for thorough root drenching.
Understanding Miracle Gro Feeder Dilution Rates
Using a hose-end feeder is one of the most efficient ways to fertilize a large garden, but understanding the dilution mechanics can be confusing. Unlike pre-mixed liquid fertilizers, the Miracle Gro Garden Feeder uses a system that mixes water from your hose with dissolved crystals from the jar.
How the Ratio Works
The standard calibration for most Miracle Gro hose-end feeders is a ratio of 1 tablespoon of dry fertilizer per 1 gallon of water output. This does not mean you put 1 gallon of water in the jar. It means that for every gallon of water that sprays out of the nozzle, the siphon mechanism pulls approximately 1 tablespoon worth of dissolved nutrients from the jar.
This is why the water in the jar turns blue (or the color of the fertilizer) and stays full until the fertilizer is depleted. Fresh water enters the jar to dissolve the crystals, and the concentrated solution is siphoned out into the stream.
Standard Dosing Reference
1 Tablespoon per Gallon: The standard rate for most flowers, vegetables, and shrubs.
0.5 Tablespoon per Gallon: Recommended for indoor plants (if using a watering can) or delicate seedlings.
Full Feeder (1 lb / ~450g): A standard refill packet contains about 1 lb of fertilizer. This equates to roughly 30-32 tablespoons. At the standard ratio, one full feeder will produce approximately 32 gallons of nutrient solution.
Calculations Explained
This calculator helps you estimate three critical factors for your gardening schedule:
Total Solution Produced: Formula: Total Tablespoons ÷ Dilution Ratio (Tbsp/Gal)
If you add 16 tablespoons (half a box) and use the standard ratio (1 tbsp/gal), you will generate 16 gallons of feed.
Estimated Coverage Area: Formula: Total Solution (Gal) × 10 sq ft
While coverage varies by soil type and plant density, a general rule of thumb for a "thorough drench" is that 1 gallon of solution covers 10 square feet of garden bed.
Time to Empty: Formula: Total Solution (Gal) ÷ Hose Flow Rate (GPM)
If your hose outputs 2.5 gallons per minute (average pressure), and you are generating 16 gallons of feed, the feeder will run clear in approximately 6.4 minutes.
Troubleshooting Feeder Issues
If your calculator results don't match your experience (e.g., the feeder empties too fast or never empties), consider these factors:
Clogged Jet: If the water stays clear or the level never drops, the tiny siphon jet inside the lid may be clogged with undissolved crystals.
Water Pressure: Low water pressure can prevent the siphon from working effectively, altering the dilution ratio.
Pre-mixing: Never fill the jar completely with water before starting. Add the powder, and let the hose fill the jar to ensure proper concentration.
// Handle custom ratio visibility
var ratioSelect = document.getElementById('feedRatio');
var customGroup = document.getElementById('customRatioGroup');
ratioSelect.onclick = function() {
if (this.value === 'custom') {
customGroup.style.display = 'block';
} else {
customGroup.style.display = 'none';
}
};
// Ensure visibility updates on change as well
ratioSelect.onchange = function() {
if (this.value === 'custom') {
customGroup.style.display = 'block';
} else {
customGroup.style.display = 'none';
}
};
function calculateFeed() {
// Get Input Values
var powder = parseFloat(document.getElementById('mgPowder').value);
var flow = parseFloat(document.getElementById('hoseFlow').value);
// Determine Ratio
var ratioVal = document.getElementById('feedRatio').value;
var ratio = 1.0; // Default
if (ratioVal === 'custom') {
ratio = parseFloat(document.getElementById('customRatioVal').value);
} else {
ratio = parseFloat(ratioVal);
}
// Validation
if (isNaN(powder) || powder <= 0) {
alert("Please enter a valid amount of fertilizer powder.");
return;
}
if (isNaN(flow) || flow <= 0) {
alert("Please enter a valid hose flow rate.");
return;
}
if (isNaN(ratio) || ratio 0 && seconds > 0) {
document.getElementById('resTime').innerHTML = minutes + " min " + seconds + " sec";
} else if (minutes > 0) {
document.getElementById('resTime').innerHTML = minutes + " min";
} else {
document.getElementById('resTime').innerHTML = seconds + " sec";
}
}