When to Use 46-0-0 Fertilizer | Urea Fertilizer

Fertilizers with considerable amounts of nitrogen such as 46-0-0 fertilizer, need to be used with absolute care. In proper doses, they can help to revitalize barren soil and reinvigorate a once-neglected lawn.

Discovered by accident during an unrelated experiment in 1828, urea, a waste material expelled by mammals, was found to consist of 46% nitrogen. Far higher than any other form of dry nitrogen.

Over 90% of global urea production goes into gardening applications like 46-0-0 fertilizers. Due to cheap production costs, urea fertilizers gained fast popularity among farmers and sod wholesalers who sought to keep their own costs down.

Overuse of very high nitrogen fertilizers – if not used correctly – can release harmful pollutants into the environment which can be detrimental to people, pets, and plants. Here’s all you need to know about when to use the 46-0-0 feed and how to use it safely.

Why Use Urea Fertilizer

While not organic or for continual use, the primary reason for using a urea fertilizer is to vastly increase nitrogen availability, when necessary. Especially for heavy nitrogen feeders like lawns and large, non-flowering evergreens.

When urea breaks down, ammonium molecules are released and absorbed by plants. Infertile soil, beneficial bacteria oxidize these molecules, which then produce moisture. Here, there is less risk of a urea fertilizer drying out your plants, if overused.

When used appropriately, lush foliage and lawn growth can result. Healthy foliage leads to successful photosynthesis, which circles back to overall plant health.

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Understanding 46-0-0 Fertilizer Label?                          

With so many fertilizer options out there, determining which one your plants actually need may seem time-consuming. But, finding the right one is easy when you understand the labeling.

Most labels state the product’s NPK (how much nitrogen, phosphorus, and potassium the product contains). With urea fertilizer, it’ll just be straight nitrogen. The back label should list all included secondary micronutrients like calcium, magnesium, and others that support plant health.

But typically, secondary micronutrients and trace elements aren’t added to urea fertilizer. With all this talk of NPCs, you may still be wondering what it is.

N-P-K Ratio

Most fertilizers display a three-numbered formula. This is its N-P-K ratio. A 46-0-0 ratio has 46% nitrogen, 0% phosphorus and 0% potassium. The rest consists of fillers or additives that make the product easier to use.

When used properly, a 46-0-0 ratio can help transform nutrient-deficient dirt into a healthy growing medium. But after planting, adequate amounts of phosphorus, potassium, and other micronutrients will need to be added for overall plant health.


Nitrogen focuses on healthy foliage growth, by fueling the production of chlorophyll. While giving plants their green color, chlorophyll ensures that captured energy converts starches and carbohydrates into food.

Nitrogen also fuels proteins and enzymes that regulate water and nutrient uptake. High-nitrogen fertilizers are typically formulated for non-flowering plants.


Phosphorus is critical to photosynthesis as it triggers the conversion of starches and carbohydrates into food, utilizing captured energy.

It also supports bud production on flowering plants, as well as robust root systems. While simultaneously forming the same proteins and enzymes that nitrogen uses to regulate water and nutrients.


Potassium circulates water, nutrients, and photosynthesized food throughout plants. It also activates those phosphorus and nitrogen-built proteins and enzymes, promoting a healthy lawn.

Potassium increases disease and environmental stress resistance by helping plants conserve moisture. And is especially effective in encouraging a lawn’s tolerance for cold winters while dormant.

Using 46-0-0 Fertilizer

A 46-0-0 NPK is used by lawn owners, farmers, and gardeners because of its versatility in application. But, since it only offers nitrogen, phosphorus, potassium, and other vital nutrients should be supplemented for plants that require them.

The key to efficient use is to incorporate a 46-0-0 fertilizer into the soil, by tilling, prior to adding any plants. You could also introduce it to the soil by mixing a water-soluble form into your irrigation water.

When spreading granules, a one-quarter inch of rainfall is enough to blend urea deep enough into the soil to avoid ammonia loss and thus, benefits plants.

46-0-0 for Lawns

It is highly recommended that a 46-0-0 NPK fertilizer be applied to your lawn only after a soil test has indicated a lack of nitrogen in the soil. When such high concentrations are applied where adequate levels of nitrogen are already present, root burn and a crispy, brown lawn could result.

Apply urea fertilizer only to actively growing grass and just until a 2nd soil test has shown improved nitrogen presence.

Ornamental Grasses

Ornamental grasses are quite popular due to their low-maintenance reputation and their ability to perform well in poor soil. Naturally resistant to disease, pests, and environmental stresses, they are unlikely candidates for high nitrogen fertilizer.

These grass types don’t require regular fertilizing, in general, and often provide year-round garden interest. But, when planted in nutrient-lacking soil, with other ornamentals, a significantly watered-down dose of urea fertilizer could help roots establish themselves faster.

46-0-0 Fertilizer for Corn

In order to support thick stalks and large leaves that encase densely packed cobbs, corn plants are heavier nitrogen feeders. Along with other important macro and micronutrients, corn uses nitrogen to produce sweet and well-formed crops.

If you see the leaves on your corn begin to brown out of season or the cobbs are small and missing kernels, a handful of polymer-coated 46-0-0 granules can boost nitrogen access for healthier plants. However, I would only suggest fertilizing corn with 40-0-0 in the vegetative and early cropping stages of growth.

46-0-0 for Leafy Vegetables

Leafy vegetables, like lettuce, broccoli, and cabbage, seldom flower and therefore rely more on nitrogen to create well-formed, vibrant foliage and florets.

When nitrogen is lacking in the soil, an initial dose of 46-0-0 fertilizer will promote strong roots, deep color, and increased size.

Liquid methods should be applied during cooler hours of the day to avoid leaf burn. Spreading granules three inches away from each plant will do the same.


Limited to pots, houseplants are especially sensitive to the amount of fertilizer they receive. Even with the increased runoff that is typical with houseplants, only a heavily diluted dose of 46-0-0 fertilizer would be appropriate. Even then, only for non-flowering plants. 

When applied properly, this method can be very effective when recycled potting soil is frequently used. Over time, potting soil will lose its inherent nutrient properties. Limited use of urea fertilizer can help restore some fertility.

Trees and Shrubs

Considering the size of most trees and shrubs when fully grown, they’re often the heaviest nitrogen feeders of any plant. As this is the nutrient that triggers the greatest growth response.

When growing in a flat area, liquid urea can be applied to trees at a rate of 2 diluted ounces per month.

On slopes or areas where the potential for run-off is higher, slow-release granules will offer the safest method of nitrogen infusion.

Can You Use Too Much 46-0-0 Urea Fertilizer?

Yes, too much urea can result in fried plants, as roots experience a severe chemical burn. Also, keep in mind that urea tends to adversely raise soil pH.

Ammonia in the soil, when kept in check, can be beneficial to plants. But, too much 46-0-0 fertilizer will increase ammonia to a detrimental level.

It’s also important to note that a liquid urea fertilizer application should always be followed by a good watering. Otherwise, the area will dehydrate the soil by absorbing water molecules within it, leaving none for your plants.

46-0-0 Fertilizer Application Rate

In light of the risks, a 46-0-0 urea fertilizer should be applied only as recommended by the manufacturer. But, here are some general guidelines for different application scenarios:

  • For lawns: apply one pound of fertilizer per 1,000 square feet of lawn.
  • For vegetable gardens: apply 4 ounces (½ cup) of fertilizer per 30 ft of row.
  • For ornamental beds: apply 0.2 to 0.4 pounds per 100 sq ft.

How to Apply 46-0-0

For best results, urea fertilizer (in any form) should be worked into the soil prior to planting.

Granules can be spread on lawns any time of day, preferably just before a rainfall. But, liquids should be applied during cooler hours to reduce the chance of ammonia burning on grass blades.

This also applies to established vegetable and ornamental beds with the added option to use a liquid as a foliar spray.

Where to Buy 46-0-0 Fertilizer

46-0-0 fertilizers can be found at most garden centers and online lawn and garden care shops. You’ll find a wide variety of both liquid and granular forms.

Liquids allow the opportunity for further dilution for plants that don’t require such high levels of nitrogen.  While granules require fewer applications and last longer.

You can pick up 46-0-0 here on Amazon.com or here at DoMyOwn.com

What Are The Disadvantages Of Urea Fertilizer?

When used appropriately, urea can greatly increase nitrogen availability in soil and rapidly revive tired lawns. But, there are a few disadvantages to consider before using it.

  • A common impurity in synthetic forms of urea is called biuret, which actually impairs plant growth.
  • Urea doesn’t mix well with certain organic compounds like limestone (organic phosphorus).
  • Urea has a very short shelf life. With only small amounts recommended, a large bag could be wasted.
  • Ammonia in urea can be harmful to eyes, skin and respiratory tracts.
  • Ammonia may become a contaminating agent in soil.

Different Fertilizer Types

There are four different classes of fertilizer that offer flexible options for usage and gardening style.

  • Quick Release – As a liquid, this option will green up lawns rather quickly, when used appropriately.
  • Slow-Release – Heavily concentrated, urea form and sulfur-coated granules or spikes can improve growth with less risk of plant burn.
  • Organic – while derived from natural animal processes, urea is not categorized as organic. But, well-rotted compost and other organic materials do contain beneficial amounts of nitrogen, phosphorus and potassium.
  • Inorganic – naturally derived or synthetically manufactured, urea is considered an inorganic product. These can produce greater results. But, can also potentially contaminate soil and nearby water sources.

Liquid Concentrate

Most liquid concentrate fertilizers are used by applying a water-diluted amount around your plants. Some are also formulated to be used as foliar sprays.  Nutrients are then immediately carried to the root system through the soil or leaves.

Liquid urea feeds tend to temporarily increase soil pH but are quite economical. However, caution is recommended, as over-feeding is common and could lead to root, flower, and foliage burn.

Water Soluble Powder

Powdered urea options can be worked directly into the soil around the base of shrubs and plants or diluted in water as a “tea”. They also store well in an air-tight container but have a short shelf life.

While one of the most economical, powders may be better suited for larger applications such as in a coppice or on farms. As these can be overwhelming in smaller gardens, if exact measurements are not followed.

Slow-Release Granules

Heavily concentrated, granules are easy to use and provide consistent nourishment for up to nine months. With the first results showing in just a couple of weeks. These are also less likely to cause root burn.

Granular fertilizers are applied by casting them evenly around the base of trees, shrubs, and plants. No watering is needed to activate them, and they are less likely to leach into nearby surfaces or groundwater.

Fertilizer Spikes

Spikes are one of the most convenient to use, especially if you have a container garden. Pre-measured in various sizes, they’re easy to push into loamy soil.  And being slow-releasing, they run little risk of burning.

Nutrients are released from the spikes by micro-organisms that naturally live in the soil. And carry the added benefit of stimulating an increased resistance to disease and pests. Unused portions can then be stored mess-free until needed.

46-0-0 Fertilizer FAQ’s