What is 12-12-12 Fertilizer Good For? - When and How to Use It? - Backyard Gardeners Network (2024)

When it comes time to choose a fertilizer for your lawn or garden, it can be difficult to choose between the plethora of options! One of the best places to start is by looking at the NPK ratio.

A 12-12-12 fertilizer contains 12% of nitrogen, phosphorus, and potassium. While it’s not suitable for every plant, it can work well for many different types of plants.

Join us as we explain more about 12-12-12 fertilizer and describe some of the ways you can use it.

What Is 12-12-12 Fertilizer?

To understand what a 12-12-12 fertilizer is, you’ll first need to understand what fertilizer numbers mean. In brief, the three numbers on a fertilizer label refer to the NPK ratio, which explains the amount of nitrogen, phosphorus, and potassium in a product.

If you’d like to learn more about fertilizer numbers, you can read our article.

A 12-12-12 fertilizer contains 12% nitrogen, 12% phosphorus, and 12% potassium by weight. It may only contain these three macronutrients, or it may also contain various secondary nutrients and micronutrients.

What Is 12-12-12 Fertilizer Used For?

You can use 12-12-12 fertilizer when you want to apply an equal amount of nitrogen, phosphorus, and potassium.

You can use 12-12-12- fertilizer for lawns, vegetable gardens, fruit trees, and shrubs. However, you should avoid using it on houseplants and flowering plants that are blooming.

For houseplant fertilizers, you can read this article.

I’ll go into more details about using 12-12-12 for different types of plants later on.

Types of 12-12-12 Fertilizer

Since a triple 12 fertilize contains a relatively high amount of nitrogen, phosphorus, and potassium, most available products will be made from synthetically produced nutrients. Organic options for 12-12-12 fertilizer are hard to find unless you blend your own mix.

With that said, you can find various forms of 12-12-12 fertilizer.

Granular Fertilizer

Granular fertilizer is the most common type of triple 12 fertilizer. It consists of small solid pieces of fertilizer that dissolve in water to release nutrients.

Applying granular fertilizer is simple—sprinkle the granules on the ground and water well. Mixing the granules into the top few inches of soil can be helpful, but it’s unnecessary.

Granular fertilizer is typically available in the short term, but there are also extended-release versions. These products contain some granules that are coated in a time-release material that slowly releases nutrients into the soil over time.

Liquid Fertilizer

Liquid 12-12-12 fertilizer is not as common as solid products. However, you can apply it to your plants if you find it.

Before you apply liquid fertilizer, you’ll dilute it following product instructions and then water the base of your plant.

When and How to Apply 12-12-12 Fertilizer?

Application times and rates depend on the type of plant you are fertilizing. I’ve included some information about properly fertilizing plants using 12-12-12 fertilizer.

Grass

If you’re planting a new lawn or looking to give your grass a boost of nutrients in the spring, a 12-12-12 starter fertilizer can be a good option. While the high amount of phosphorus may encourage the formation of unsightly seed heads, this isn’t guaranteed to happen.

If you’re planting a new lawn or reseeding an already existing lawn, you can spread fertilizer before planting your grass seed.

It’s important to evenly apply 12-12-12 fertilizer to your grass to ensure the whole lawn has access to nutrients. While you can use your hands to broadcast the fertilizer, I find that a fertilizer spreader makes the job much easier.

Determining the size of your lawn is the first step to applying triple 12 fertilizer. Once you’ve done this, you can calculate how much fertilizer you need to apply.

The application rate for lawns is three pounds per every 1000 square feet of established lawn or six pounds for 1000 square feet of new lawn. If you’re applying fertilizer at a larger scale, you can apply 200 pounds of 12-12-12 per acre.

You can look at your spreader to determine the setting that will allow you to apply the correct rate, as each type of spreader has different calibration settings. We’ve included some common 12-12-12 spreader settings for three pounds per 1000 square feet to get you started.

• Elite: 5.25
• Scotts Edgeguard DLX: 5.25
• Scotts Edgeguard Mini: 5.25
• Earthway 2600 A Plus: 14
• Earthway 2050: 14
• Lesco: 14
• Echo RB60: 5.5

While you can reapply triple 12 fertilizer every two to three months in the spring through fall, I recommend switching to a fertilizer that is designed for lawns. A product with an NPK ratio like 30-0-4 or 33-2-5 is a better choice for lawns in the long term.

Vegetable Garden

If you have a mixed vegetable garden, 12-12-12 fertilizer can be a good option, especially if you aren’t sure about the composition of your soil. I always conduct a soil test before planting a garden in a new spot, but I understand this isn’t always feasible.

If you’re unsure about the nutrients in your soil, a triple 12 fertilizer can give your plants a good baseline dose of nutrients early on.

Since most triple-12 fertilizers contain nutrients readily available to plants, I like to apply the fertilizer anywhere from a week to a day before planting my garden.

While it’s okay to use 12-12-12 fertilizer for a base-level source of nutrients, I recommend switching to a more specialized fertilizer once your plants are about a month old. I like to apply a fertilizer with higher amounts of phosphorus and potassium to fruiting crops like tomatoes, cucumbers, and peppers. Some suitable NPK ratios include 3-5-4 and 10-15-15.

Fruit Trees

A 12-12-12 fertilizer will supply a fruit tree with the macronutrients it needs, making it a good fertilizer choice. It’s true that fruit trees will benefit more from a fertilizer containing more nitrogen and potassium than phosphorus. However, a 12-12-12 fertilizer is better than no fertilizer at all.

It’s essential to avoid fertilizing your fruit tree at planting since this can lead to fertilizer burn. You should also make sure to avoid over fertilizing.

The best time to fertilize your fruit trees is in the early spring, around the time buds are beginning to open.

Look at the size of your tree to determine how much fertilizer to apply. You’ll want to apply about one pound of fertilizer for each inch of the trunk’s diameter.

Sprinkle the fertilizer in a circle around the tree’s base, about one to three feet away from the trunk.

Houseplants

I don’t use 12-12-12 fertilizer for houseplants, as it can burn delicate houseplants. Instead, you can use a 3-3-3 or 2-2-2 fertilizer.

Flowering Plants

Triple 12 fertilizer can give flowering plants a good start. Some flowering plants that can benefit from 12-12-12 fertilizer includes flowering shrubs like roses, azaleas, and rhododendrons, as well as perennials like black-eyed Susans, coneflowers, and columbine.

Early spring is the best time to apply 12-12-12 fertilizer to flowering plants. Sprinkle about one tablespoon around the base of smaller perennial flowers and a few tablespoons around larger flowering shrubs.

While 12-12-12 can give your flowering plants a good boost in the spring, I recommend switching over to a fertilizer designed for flowering plants after this first application. These fertilizers will have higher amounts of phosphorus to support the production of flowers.

How Long Does It Take Triple 12 Fertilizer to Work?

Since most types of triple 12 fertilizers are made from synthetic ingredients, the nutrients are in forms that plants can take up. Therefore, the fertilizer does not have to be broken down by bacteria or other microorganisms before it is available to plants.

That means plants can begin taking up most types of 12-12-12 fertilizer as soon as you apply it and water it. However, that doesn’t mean that your plants will change before your eyes!

If your plants were experiencing signs of nutrient deficiencies before you applied the triple 12 fertilizer, it will likely take at least a week before your plants begin to improve.

My Top Choices for Triple 12 Fertilizers

If you want to apply a 12-12-12 fertilizer to your plants, I think the following products are a great place to start.

GroundWork 12-12-12 All Purpose Fertilizer

If you’re looking for 12-12-12 fertilizer for jumpstarting your lawn or vegetable garden, this product from GroundWork can be a good option. The granular fertilizer comes in 40 pound bags which means you can purchase just a bag or two for your lawn rather than five or ten smaller bags.

Like all 12-12-12 fertilizers, GroundWork All Purpose Fertilizer contains 12 percent nitrogen, 12 percent phosphorus, and 12 percent potassium. All of these nutrients exist in synthetic forms.

This percent of macronutrients means that the fertilizer provides enough nutrients for rapidly-growing spring plants.

It’s important to note that this product does not contain other nutrients like calcium and magnesium. Therefore, you may need to apply another fertilizer to supply your plants with the secondary nutrients and micronutrients they need to thrive.

Applying this triple 12 fertilizer is easy. If you’re fertilizing individual plants like shrubs and perennial flowers, you can measure out the proper amount of fertilizer and apply it by hand. And if you’re fertilizing a larger yard or garden, you can calibrate a spreader and use this to evenly distribute the product.

Look for GroundWork 12-12-12 at large retailers such as Tractor Supply Company. While prices can vary depending on location and supply chains, this is typically a relatively affordable product. At the time of publishing, a 40 pound bag cost $19.99.

Yard Mastery 12-12-12 Starter Fertilizer with Bio-Nite

This triple 12 fertilizer also contains 12 percent of nitrogen, phosphorus, and potassium. This means that this fertilizer provides a good amount of macronutrients to lawns, vegetable gardens, trees, shrubs, and more.

Along with the macronutrients, this product also contains some secondary nutrients and micronutrients. It contains 0.5% magnesium, 7.34% sulfur, 3% iron, 0.5% manganese, and 0.05% zinc. These nutrients can help support plants in ways macronutrients cannot.

Along with nutrients, this fertilizer contains Bio-Nite. While many people think that biosolids like Bio-Nite are dried human excrements, this isn’t the case. Instead, Bio-Nite is made from dried microbes that have digested sewage waste.

If you haven’t heard of Bio-Nite, you may have heard of Milorganite. These two products are very similar, but Bio-Nite is sourced from South Florida while Milorganite is from Milwaukee.

Adding Bio-Nite to your soil can help support soil microbes that contribute to plant health.

You can purchase this 12-12-12 fertilizer from Yard Mastery.

At the time of writing, a 45 pound bag cost $39.99. While this is more expensive than the GroundWork 12-12-12 fertilizer, it’s important to remember that the Yard Mastery product also contains additional nutrients.

Frequently Asked Questions

Can You Use 12-12-12 Fertilizer for Tomatoes?

Triple 12 fertilizer can work well for tomatoes when they are still in their vegetative stage. This stage typically lasts for between one and two months after the tomato seeds germinate.

You should switch over to a higher phosphorus fertilizer once tomato plants begin to produce flowers. This will encourage plants to produce more flowers and also support the development of healthy fruits.

What Is the Difference Between 10-10-10 and 12-12-12 Fertilizer?

Both 10-10-10 and 12-12-12 fertilizers are balanced fertilizers with similar nutrient contents. However, triple 12 fertilizer contains more nutrients per weight than triple 10.

This means that you can apply less triple 12 fertilizer than triple 10 fertilizer but still apply the same amount of nutrients to your plants.One product isn’t necessarily better than the other. Instead, it’s a matter of personal preference and product availability.

Wrapping Up

A 12-12-12 fertilizer can be an appropriate choice for lawns, mixed vegetable gardens, shrubs, and more. However, it’s important to apply the proper amount of fertilizer to avoid burning your plants.