Can You Mix Granular Fertilizer With Water? Complete Guide

Can you mix granular fertilizer with water to create a liquid solution?

The short answer is yes… but there’s a catch. While you CAN dissolve many granular fertilizers in water, not all of them are designed for it. And if you do it wrong, you could end up wasting money (or worse, damaging your plants).

I learned this the hard way back in 2019 when I tried to dissolve some slow-release fertilizer pellets for my tomato plants. Let’s just say the results weren’t pretty.

But here’s the good news:

Once you understand which granular fertilizers work in water and HOW to mix them properly, you can save money and give your plants exactly what they need.

In this guide, as a professional fertilizer mixer machine manufacturer, I’ll show you exactly how to turn granular fertilizer into liquid fertilizer, which types work best, and the mistakes you need to avoid.

can you mix granular fertilizer with water

Table of contents

Why Mix Granular Fertilizer With Water?

Here’s the thing:

Liquid fertilizers can cost 3-5x more than granular versions with the same nutrients.

So why not make your own?

But beyond saving money, there are actually some solid reasons to convert granular to liquid:

Fast absorption. When I tested liquid vs granular on my container plants last spring, the liquid-fed plants showed visible improvement in just 48 hours. The granular? It took nearly two weeks.

Even distribution. Ever notice those dark green spots on your lawn where fertilizer granules sat too long? Liquid fertilizer eliminates that problem completely.

Cold weather performance. Granular fertilizers basically go dormant when soil temps drop below 50°F. But liquid fertilizers? They keep working even when it’s chilly.

Dog-proof application. My neighbor’s golden retriever thinks blood meal is a gourmet snack. When you dissolve it first, Fido can’t dig it up and chow down.

Which Granular Fertilizers Can You Mix With Water?

Not all granular fertilizers play nice with water.

Here’s what actually dissolves:

Water-Soluble Types

Synthetic fertilizers (like Miracle-Gro)
Ammonium sulfate (21-0-0)
Urea (46-0-0)
Potassium sulfate
Most NPK blends without coatings

Won’t Dissolve Properly

Slow-release fertilizers with polymer coatings
Organic matter like compost or manure pellets
Bone meal (only partially dissolves)
Rock phosphate
Time-release formulas

Pro tip: Check the bag. If it says “water-soluble” anywhere, you’re golden. If it mentions “slow-release” or “coated,” stick to dry application.

Step-By-Step: How to Mix Granular Fertilizer With Water

I’ve tested dozens of methods over the years. This one works best:

What You’ll Need:

Granular fertilizer (water-soluble type)
Bucket or container
Warm water
Stirring stick
Strainer or cheesecloth
Measuring cup

The Process:

1. Measure Your Ratios

The standard ratio is 1 cup of fertilizer per gallon of water.

But here’s the thing: that’s just a starting point.

High-nitrogen fertilizers? Use 3/4 cup per gallon.
Balanced fertilizers? Stick with 1 cup.
First time? Start with 1/2 cup to be safe.

2. Use Warm Water

This was a game-changer for me. Warm water (around 80-90°F) dissolves fertilizer 2x faster than cold water.

Don’t use boiling water though – it can break down some nutrients.

3. Mix and Wait

Add your fertilizer to the water and stir thoroughly. Then here’s the key: let it sit for 24 hours.

Stir it every few hours if you can. This ensures complete dissolution.

4. Strain the Solution

Even “water-soluble” fertilizers leave some residue. Use a fine strainer or cheesecloth to remove any particles.

(Skip this step and you’ll clog your sprayer. Trust me on this one.)

5. Apply Immediately or Store Properly

Fresh is best. But if you need to store it, use an airtight container and keep it cool. Use within 1-2 weeks max.

Application Methods That Actually Work

Once you’ve got your liquid gold ready, here’s how to use it:

Foliar Feeding

Spray directly on leaves for fastest absorption. Best for:

Nutrient deficiencies
Quick green-up
Vegetable plants during fruiting

Dilute to 50% strength for foliar application to avoid leaf burn.

Soil Drench

Pour directly around the root zone. Use:

1-2 cups per small plant
2-4 cups per shrub
6-8 cups per tree

Through Irrigation

Add to your watering can or irrigation system. This is my favorite method for container plants.

Common Mistakes to Avoid

I’ve made all of these mistakes so you don’t have to:

Using the wrong fertilizer type. I once spent an hour trying to dissolve Osmocote pellets. Spoiler: they’re coated for a reason.

Over-concentrating. More is not better. I burned an entire flat of seedlings learning this lesson.

Applying in hot sun. Liquid fertilizer + hot leaves = crispy plants. Apply in early morning or evening.

Not testing first. Always test on a few plants before going all-in.

Ignoring the leftovers. Those undissolved bits still have nutrients. Toss them in your compost or sprinkle on established plants.

When Liquid Beats Granular (And Vice Versa)

Liquid fertilizer isn’t always the answer. Here’s when each type shines:

Use Liquid When:

Plants show nutrient deficiency
Soil temperature is below 50°F
You need precise application
Growing in containers
Establishing new transplants

Stick With Granular When:

Fertilizing large areas (like lawns)
You want slow, steady feeding
Budget is tight
Storage space is limited
Applying to established landscape plants

Real Results: My Side-by-Side Test

Last year, I ran a test on my tomato plants:

Group A: Fed with homemade liquid fertilizer (dissolved 10-10-10)
Group B: Fed with the same 10-10-10 applied dry

The results after 30 days:

Liquid-fed plants were 18% taller
First fruit appeared 6 days earlier on liquid-fed plants
Both groups had similar total yields by season end

The takeaway? Liquid gives you a faster start, but both methods work long-term.

Money-Saving Alternative: Water-Soluble Fertilizers

Here’s something most people don’t realize:

Some fertilizers are DESIGNED to dissolve in water. They cost more than regular granular but way less than pre-mixed liquids.

My favorites:

Jack’s Classic 20-20-20
Miracle-Gro Water Soluble
Greenway Biotech’s Blossom Green

These dissolve instantly and completely. No straining required.

The Bottom Line

Can you mix granular fertilizer with water? Absolutely.

But success depends on:

Choosing water-soluble fertilizers
Using the right ratios
Allowing time for complete dissolution
Straining before application

Is it worth the effort? If you’re fertilizing a few houseplants, probably not. But if you’re managing a garden or want to save money on liquid fertilizer, it’s a game-changer.

Just remember: start with less fertilizer than you think you need. You can always add more next time, but you can’t unfertilize burnt plants.

Have you tried making your own liquid fertilizer? I’d love to hear what worked (or didn’t work) for you.

Because at the end of the day, the best fertilizer method is the one you’ll actually use consistently. And if mixing granular fertilizer with water helps you feed your plants more regularly, then that’s a win in my book.