0 20 20 Fertilizer When to Use Zero Nitrogen | SOLVED

Most of us gardeners know that if you want your garden to thrive then fertilizer is a necessity. It gives the soil the nutrients our plants need to grow healthy and strong. 

But when it comes to using 0 20 20 fertilizer knowing when to use it and what the numbers on the fertilizer bags mean can become confusing. 

To avoid a wasted purchase and to understand its purposes and dangers if used incorrectly I’ve made it simple and laid out all the details here in this article. Let’s get to the bottom of this.

When to Use 0-20-20 Fertilizer Zero Nitrogen

Yes, you read that right. Zero nitrogen. But wait, don’t plants need nitrogen? So why do you need a fertilizer without nitrogen? 

Turns out that it’s a great way to “winterize” your garden and prepare it for dormancy, and adverse weather and protect it from the onset of potential disease. 

Plants use little to no nitrogen in the winter so why pay more when it will just be wasted. 

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Understanding 0 20 20 Fertilizer Label

You want to make sure your plants are getting the nutrition they need, but there are so many choices when it comes to choosing a fertilizer. 

There are certain rules that all fertilizer makers must follow when labeling their products and understanding these rules can make comparing fertilizers so much easier. 

Here are some things you need to know about garden fertilizers and their labels. 

N-P-K Ratio

The three numbers known as N-P-K numbers stand for nitrogen, phosphorus, and potassium. So 0 20 20 would mean 0% nitrogen, 20% phosphorus and 20% potassium. 

The remaining 60% is made up of ‘filler’ which usually consists of various materials like sand, limestone, sawdust, sterile dirt, peat moss, sphagnum, ground corn cobs, and more.


Nitrogen is responsible for making plants grow greener leaves. Plants that are mostly leaves need a lot of nitrogen, especially during the summer months in their active growing season so look for a fertilizer where the first number is higher. The higher the number, the more nitrogen the fertilizer will give. 


Phosphorus supports root development so that plants can pierce through the ground and gather all the nutrients they need. It also increases bloom and fruit production. 

Plants low in phosphorus take time to mature and when they do, the fruits or seeds they bear are few and poor in quality. Tomatoes and root veggies love a 5-10-10 mix.


With potash as its nickname, potassium helps the plant to fight off diseases. It also helps invigorate the plant, enabling it to fight against extreme temperatures. 

Plants lacking potassium may display stunted leaves and fruit and may also be extra sensitive to drought. Most soils already have potassium, that’s the reason the third number in the fertilizer ratio is normally the lowest.

Why Use Zero Nitrogen Fertilizer

There are three possible reasons why people use zero nitrogen fertilizer. 

Some plants need to be fertilized in the fall. This is to help them adjust to falling temperatures and adverse weather conditions as well as help them fight off diseases. 

I know that most plants and trees go dormant in the wintertime and don’t need the addition of as I learned, nitrogen helps plants grow green leaves so the nitrogen is what is responsible for lush green foliage and strong, healthy root growth. It did for would just be wasted as the plant doesn’t need it when dormant anymore. 

Some gardeners use zero nitrogen fertilizer when they know that the soil is already nutrient-rich and where the addition of more nitrogen may affect pH levels. nutrient  Plants Another reason is that nitrogen is easily soluble. It will wash away with the snow and rain and leech into streams and waterways so the nitrogen will just go to waste. 

Interestingly enough, people also use 0 20 20 fertilizer for clover fields. Not only do clovers increase nitrogen in depleted soils, but people also plant them to attract deer. In the wild, these animals love the taste and it gives them the nutrition they need. 

How to Make Zero Nitrogen Fertilizer

Making your own zero nitrogen fertilizer is simple and affordable. Look for phosphorus only 0 20 0, and potassium only 0-0-20 fertilizers when purchasing. 

I recommend buying each fertilizer separately as it will be easier to measure and mix but if you go for a fertilizer that has both phosphorus and potassium make sure they have equal amounts of each. For example, a 0-5-5 ratio.

You’ll also need to get filler material. As the calculation above shows, phosphorus and potassium minerals only make up 40% of the fertilizer mix so you still need 60% of some other kind of material to complete your fertilizer. You can use almost anything as a filler material like sand, sawdust, limestone, peat moss, or sterile soil.

The type of filler you use will depend on what your soil needs. For example, if you want to prevent the growth of weeds, grass cuttings are an excellent option. Sawdust filler is great for helping to maintain moisture and nutrients. 

Now for the fun part. Mixing! If you are mixing large amounts, placing a tarp on the ground will work best or for smaller portions, you can use a container. 

Next, place equal parts of phosphorus and potassium on the tarp. I find it easier to measure by the scoop. The ration would be 1 scoop phosphorous, 1 scoop potassium, and 3 scoops filler. If you prefer weighing, PennState shows you how to easily calculate. 

Now get to mixing. Use a straight-edged shovel to combine the ingredients. Once you’ve finished, transfer it to a bucket or a sack for storage, and be sure to label it to avoid confusion. 

Where to Buy 0 20 20 Fertilizer

Unfortunately, stores have discontinued stocking most fertilizers with zero nitrogen. It is very hard to come by.  This is why some opt to make their own. 

The reason being is that many fertilizer companies are now making organic matter with a slower release. This means granular pieces take more time to leach out. 

Nitrogen is far more soluble than the other two macronutrients hence why it leeches away from the soil so easily. Busy consumers now don’t need to fertilize so often, knowing their soil can recharge on its own.

0 20 20 Fertilizer Uses

This is a great fertilizer to use with all types of plants including flowers, bulbs, vegetables, and berries – and of course, if you’re looking to increase clover. 

If you know your plants and lawn have enough nitrogen and you just want to give an extra boost of phosphorus and potassium, then this fertilizer is for you.

Trees and Shrubs

This type of fertilizer is particularly great for trees and shrubs especially if they are mature and already grown. This mix will keep the roots strong and healthy and produce beautiful and bountiful blooms. 

Fruit Trees

It is best to use a fertilizer for fruit trees in the fall just before they go dormant as this is the time, they store their energy. 

Research from the Oregon State University concludes that If you want to maximize nutrient uptake, you should forward to applying fertilizers in August or early September, it’s way more efficient than applying them in the late winter.

Early spring fertilization – whilst effective in helping to establish bud onset and later fruit development – is often washed away due to rain. They also state that using a fertilizer with high nitrogen the first year can burn roots so using a zero-nitrogen fertilizer is ideal. 

Flowers Borders

You can use 0-20-20 fertilizer in spring to develop the onset of buds in anticipation of plenty of voluminous blooms later in the season. If using, you’ll need to ensure that your potting medium or soil is already nutrient-rich.

As with fruit trees, by fertilizing your flowers in the late summer to early fall the nutrients are taken more directly into the plants and then stored for the winter. This will help to grow hearty buds, spurs, and shoots for the coming year without stimulating late growth.

Vegetable Gardens

Some vegetables do well with little to no nitrogen. For example, plants in the pea family. Excess nitrogen will delay flowering as they produce a little nitrogen of their own. Some other low-medium nitrogen feeders are carrots, parsnips, leeks, and radishes. 

Low nitrogen fertilizers are also used on cereal, rice, sugar beet, and soybean plantations. Vegetation that is leafy and herbaceous like tomatoes don’t do so well with low nitrogen as they need a good boost to help them become firm and sturdy. 

House Plants

Some people overlook fertilizing their house plants. Since houseplants are no longer in their natural environment, they may not receive some of the minerals they need to truly thrive. 

Considering most house plants are leafy plants, they will need nitrogen to encourage lively foliage growth. Using a balanced feed such as a 10-10-10 fertilizer is more beneficial here.

Lawn and Grass

Just like house plants, your lawn is mostly green and leafy and requires a lot of nitrogen. You will notice that most liquid lawn fertilizers are high nitrogen fertilizers, with formulas like a 12-4-8 fertilizer. So, a zero-nitrogen fertilizer is a no go here. 

Can You Use Too Much 0 20 20 Fertilizer?

Definitely. It all depends on what kind of plants you have and how many nutrients you need. 

Excess fertilizing can also make the soil too salty, and any leftover nutrients not absorbed will leech into waterways. You can also kill your plants. Some signs of over-fertilizing are yellow, wilted leaves, rotted roots, and little to no growth.

In addition, some US states have banned the use of phosphorus-based fertilizers.

0-20-20 Fertilizer Application Rate

The application rate will usually be printed on your fertilizer’s packaging. However, the industry standard is 1lb of fertilizer per 1000 square feet.

That means you will multiply the 1lb by the 1000 sq ft and divide by the percentage converted into decimal. 

For example, if you take 20% phosphorous and turn it into decimal the equation would look like this. 

1 x 1000 = 1000 / 0.20 = 5 lb of 0 20 20 fertilizer is needed to cover 1000 sq ft.

This is just a reference, if you need something more specific then it is best to do a soil test to find the correct amount your lawn and plants need. 

How to Apply 0-20-20

Determining how much and how often you should apply your fertilizer will depend on the type of application you choose and what your plants need. 

A complete fertilizer is enough for most garden plants and should be applied in spring and later again in 2 or 3 months. Time-release fertilizers are usually applied in spring and last throughout the season. 

Different Fertilizer Types

Once you have determined how much of what minerals your plants need the next step is to decide which type of fertilizer to use.

Liquid Concentrate

Liquid fertilizers need to be diluted in water. They are best to use with house plants as you can easily put them into a watering can. Liquid fertilizers provide the fastest delivery of nutrients, but they are usually gone from the soil within two weeks and will require feeding again.

Water Soluble Powder

Powder fertilizers are easy to use and will dissolve once you add them to water before feeding your plants. Liquid and powders are both quick to be absorbed and show fast results but will have to be applied almost weekly due to run-off. 

Slow-Release Granules

Fertilizer granules can be sprinkled over the ground or incorporated into the soil. With slow-release fertilizer, you can anticipate regular time-release for your plant feedings every day. This method is better for the health of your plants.

The environment also benefits from slow-release granules. When nutrients are released in a measured manner, running off into waterways is much harder. Excessive fertilizer runoff is a big environmental problem and one that you should try to avoid.

Fertilizer Spikes

Fertilizer spikes are another type of slow-releasing fertilizer. They are easy to store and may only need to be used a couple of times per year. 

Spikes are pre-measured, so fewer chances of over-fertilizing your garden and because spikes work underground, there is no runoff or odor. Some spikes do contain formaldehyde, so choose wisely.

Final Thoughts on 0 20 20 Fertilizer

Zero nitrogen fertilizer is used to winterize fruit trees, flowers, plants, and shrubs. It will give them adequate nutrition to store for the cold months which will then give them a head start for spring without wasting precious materials and harming the environment. 

This fertilizer will give your plants root strength, help with flower and fruit production and provide overall health and weather protection benefits that your plants are sure to love.