How to use organic garden fertilizer for better plants

organic fertilizer for healthy vegetables

Me with a bumper harvest from my front yard garden!

When you’re out and about working in your garden, do you start wondering about any of the following questions?

How can I grow more healthy vegetable plants?

Should I use organic garden fertilizer when planting?

How often should I fertilize my garden and what should I use?

There’s a lot of confusion in the vegetable gardening world about fertilizing. It’s one of the most common questions other gardeners ask me when I’m traveling around speaking and teaching each season.

Most gardeners are wondering what they should be doing, if anything, and if the actions they’re already taking to build their soil fertility are the right ones.

I’m guessing you’re probably unclear about this topic, too. (Don’t worry, so was I, until a few years ago.)

In this post, we’re going to clear up any questions and doubts you have about fertilizing your garden and learn about which products you should be using to build healthy soil and grow lots of delicious and nutritious produce in your garden.

healthy garden soil

This post contains affiliate links.

Why Healthy Soil Matters to Your Garden

The health of your soil is one of the main factors that affect how successful your garden will be each season. In fact, you should be spending time and effort to build the best soil for a vegetable garden.

When your soil contains all of the nutrients the plants need they’ll grow larger and be more productive, the fruit and vegetables they produce will be a higher quality, and the plants will better resist disease and pest pressure.

Also, when we eat vegetables our bodies absorb the nutrients we need from the food. If your soil is lacking nutrients then your food will be as well.

Basically, if you don’t have healthy soil, all of your other efforts will be wasted. You simply cannot have a well-performing garden with unhealthy soil.

There could be other reasons besides soil problems that are causing your garden to struggle.

vegetable harvest from a healthy garden

A healthy garden yields lots of big and colorful harvests!

What Nutrients Plants Need to Grow

There are three primary macronutrients that all plants need to grow healthy and strong – nitrogen, phosphorus, and potassium. They are often called N-P-K for short. Plants need these nutrients in the biggest quantities.

Nitrogen helps plants put on vegetative growth. If you don’t have enough nitrogen you may notice your plants turning yellow and/or stunted growth. If you have too much, your plants may grow big and green, but not produce any flowers or fruit.

Phosphorus stimulates flower bloom and root growth. If you’re lacking phosphorus you might notice leaves turning a bit red or purple.

Potassium supports the plants’ immunity to disease and also affects the quality of fruit. If your soil is lacking in potassium you may notice that some of your fruits are thin-skinned or small and your plants are more susceptible to disease.

If you go to the garden store and look at bags of fertilizer you’ll notice there are three numbers listed on the front. They stand for the percentage of the three macronutrients it contains, like 4-5-7, or 12-0-0. (We’ll come back to fertilizer later.)

There are also three secondary macronutrients – calcium, magnesium, sulfur. And several micronutrients, which are needed in a lesser quantity by plants – chlorine, boron, copper, iron, manganese, zinc, molybdenum, and nickel.

gardener adding organic garden fertilizer

Getting ready to add some organic garden fertilizer to my soil.

When You Should Add Organic Garden Fertilizer

Over the years of teaching and consulting with lots of different gardeners, reading about soil fertility, and experiencing a lack of nutrients in my own garden (at two different homes!) I’ve become convinced that every gardener should be adding organic garden fertilizer to their soil on a regular basis.

Growing vegetable plants year after year demands a lot from your soil because they take a lot of nutrients out of your garden every season. While adding compost is a great practice, it usually isn’t enough to replace the nutrients that have been depleted. For that, you really need a balanced organic fertilizer.

Even if you think your garden is relatively healthy, you should consider adding fertilizer as an experiment to see if it could perhaps improve your plants’ health and vigor. Healthy and robust plants can mean more food harvested from your garden throughout the growing season.

For an example, last year I counted the number of red peppers on my Carmen pepper plants. Guess how many each one had? Not two or three, but fifteen!

Most of the plants produced between 12-15 ripe red peppers. I believe that’s a result of Carmen being a kicka** variety and the fact that I consistently fertilize my garden.

Each season I consistently have large and very productive plants of any given vegetable. In fact, I’ve now grown accustomed to such amazing plants that I immediately know when a garden bed is lacking nutrients by how slowly plants are growing and whether they look stunted or not.

Of course, when this happens I grab my bag of organic fertilizer and add more to that area.

pepper plants with organic fertilizer

My Carmen pepper plants loaded down with fruit!

Even new gardens can have soil fertility problems. If you’ve recently built raised beds and ordered soil to fill them up your garden isn’t immune from nutrient issues. I know this firsthand because I built a brand new garden at my current house and then my plants didn’t grow. You can read all about my soil problems.

What to Look for in a Fertilizer

When you head to the garden store to pick out a bag of fertilizer, it can be a bit overwhelming when you’re standing in the aisle in front of many different kinds and brands. Let’s break down what you’re looking for so you know which is the best choice.

#1: Choose an organic fertilizer.

Let’s talk a little bit about organic vs. synthetic fertilizers. Organic and synthetic fertilizers provide nutrients in different ways.

Organic fertilizers are made from naturally occurring mineral deposits and organic material, such as bone or plant meal or composted manure. Synthetic fertilizers are made by chemically processing raw materials.

In general, the nutrients in organic fertilizers are not water-soluble and are released to the plants slowly over a period of months or even years. These organic fertilizers stimulate beneficial soil microorganisms and improve the structure of the soil. Soil microbes play an important role in converting organic fertilizers into soluble nutrients that can be absorbed by your plants. 

Synthetic fertilizers are water-soluble and can be taken up by the plant almost immediately. In fact applying too much synthetic fertilizer can “burn” foliage and damage your plants. Synthetic fertilizers give plants a quick boost but do little to improve soil texture, stimulate soil life, or improve your soil’s long-term fertility.

Because synthetic fertilizers are highly water-soluble, they can also leach out into streams and ponds. This is a particular concern to me because I live about a mile from a lake and all of our city’s streets drain into those lakes. 

For the long-term health of your garden, and the environment of your area, an organic fertilizer is the best choice. 

The bag should say somewhere on the front that it’s approved for Certified Organic Use. In the US, you can make sure by checking for the green and white “OMRI Listed” label, which means it was certified by the Organic Materials Review Institute. Check out the video below for an example of this label on a bag of fertilizer.

#2: Look for a balanced fertilizer.

Secondly, you want to look for a bag where the numbers on the front, the N-P-K numbers we learned about above, are close to one another. For example, 5-4-6 or 8-6-7. You may notice that some fertilizers will say 10-0-1, or something like that, and that’s not what you want for your vegetable garden. Numbers somewhere in the 5 range are great.

Then, check the ingredients on the back and choose one that also has some of the secondary macronutrients – calcium, magnesium, and sulfur. And even better, look for one that has some of the micronutrients like iron, boron, or manganese.

These organic fertilizers are all good choices:

Happy Frog Tomato & Vegetable Fertilizer

Happy Frog All Purpose Fertilizer

Dr. Earth Tomato, Vegetable, and Herb Fertilizer

harvesting healthy vegetables from the garden

Where to Purchase & How Much to Buy

I recommend patronizing your local garden centers and nurseries, especially when shopping for organic fertilizer. Depending on the size bag you want to buy, this can be a heavy product with high shipping fees to order online.

If you don’t live in an area with a garden center, Amazon carries all of the fertilizers I listed above.

I have a large garden, 1600′ square feet, so I go through a lot of fertilizer each season. The smaller bags are about four lbs., so if you have a large garden you’ll likely need several bags. If you have a small garden with a few raised beds you can start with one bag and return to the store if you need more later in the season.

How to Add Fertilizer to Your Garden

As I show in the video below, when I’m prepping spring garden beds I put a small handful of fertilizer in the planting hole. And when I’m planting seeds, I’ll often work some fertilizer into the top few inches of the garden bed when I’m preparing it for planting.

But, you can also add fertilizer after you’ve already planted seeds and plants if you notice they aren’t growing as well as you had expected. I do this all of the time!

Even part way through the season, you can still make a quick trip to the garden store to buy a bag and then add it to your garden, it’s not too late.

adding organic fertilizer to garden bed

Adding organic fertilizer to a newly built garden bed at my house.

Additional Resources for Growing a Healthy Garden

Video + Shopping Checklist

If you’re having issues  don’t think soil fertility is the issue, here are four other factors that might be affecting your garden.

I created a video that walks you through how to pick out the correct organic garden fertilizer when you go shopping and then demonstrates how to apply it when you’re planting seeds and plants in your garden beds.

There’s even a companion checklist you can print out and take with you on your shopping trip .


In each season of my Masterclass – Success In Every Season: Get Better Results From Your Garden All Year Long – we focus on exactly what you need to know to be successful. The seasons build upon one another (just like in your garden!) to create a complete toolkit of skills that will set you up for a more joyful gardening experience

When you make smarter decisions in your garden, you end up having more success, which means gardening is a lot more fun. Read more about it here.

If you’ve had less than stellar results from your vegetable garden in the past few years, you should definitely be adding organic garden fertilizer. If your plants are yellow or pale green, or they don’t seem to grow full size, or they don’t produce a lot of fruit, you may have nutrient issues.

This year, I encourage you to experiment with adding at least some balanced organic fertilizer to your garden beds to see if you can foster healthier, more high-yielding plants. You don’t have much to lose, and you have a lot to gain!








  • Planting garlic in the fall is one of my favorite things to do, so I couldn’t imagine not being able to! At least now I know I can plant it in the spring here in Wisconsin with success- thank you! Also, great to hear you’re friends with Mark! Such a good guy I’ve had good conversations with over a decade ago. I know Michelle and absolutely love those two. Also, the first 5 years I gardened I thought I didn’t need to add fertilizer. My goal was to never use any and rely on horse manure from my neighbor and homemade compost. Once I actually started adding fertilizer a few years ago and saw the difference it made, I’ve never gone back. Cheers!

    • Thanks for sharing, Greg! I’ve also known Mark for many years through the gardening world of Madison. I’m so happy to hear that adding fertilizer made a big difference in your harvest. Same for me! Thanks for checking in.

  • […] Potatoes need fertile soil that’s rich in potassium and phosphorous. I recommend using an organic garden fertilizer when you […]

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