The best fertilizers
by Mary Marlowe Leverette- Plants need nutrients from the soil to grow. Selecting and adding the right fertilizer for each plant type is the key to a thriving garden.
- The type of plant and its growing conditions will help you determine which fertilizer to select.
- After extensive testing and getting expert advice, we chose Lesco 16-4-8 Polyplus Fertilizer with Iron as the best fertilizer for a plush, green lawn, and Osmocote Indoor Outdoor Organic Plant Food as the best option for spectacular houseplants.
I grew up on an apple farm where not only did we make our living off apple trees, but we also grew our own vegetables and my mother diligently tended huge flower beds. The soil was our lifeline so maintaining it was essential. Using the right fertilizers at the optimum time in the growing season was part of our annual routine. I even did my sixth-grade science project on the effect of adding different nutrients to the soil and plant growth.
In addition to absorbing a great deal of fertilizer knowledge while I was growing up, I was surrounded by soil experts in college when I served as a County Extension Agent (Consumer Science) with Clemson University. One key takeaway I learned during that time? Before any good agent recommended any type of soil amendment, they had the farmer or consumer first submit a soil sample for testing.
If you're really serious about your yard and garden, you can follow their lead and purchase soil testing kits online or work with your state Cooperative Extension Service for testing. Soil testing is the best way to learn about your specific soil's needs and will help you better prepare to choose the right fertilizer nutrient mix.
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The soil test report will focus on the three most important nutrients that plants need: nitrogen, phosphorous, and potassium. Every fertilizer must include an analysis of these nutrients and the three numbers are always listed in that exact order. For example, a bag of 16-4-8 fertilizer contains 16 percent nitrogen, 4 percent phosphorous, and 8 percent potassium.
However, if getting into soil testing sounds daunting, start here for a guide to great general fertilizer options for your plants. Since types of soil and growing conditions vary widely, we've chosen to focus on the best basic fertilizers for lawns, houseplants, vegetables, trees and shrubs, and flowers. The top picks were chosen based on expert advice and my own tests in my home garden to ensure optimum growing results that won't cause harm to the plants or the environment.
Here are our top picks for the best indoor and garden fertilizers:
- The best for lawns: Lesco 16-4-8 Polyplus Fertilizer with Iron
- The best for indoor plants: Osmocote Indoor Outdoor Organic Plant Food
- The best for vegetable gardens: Hyponex All Purpose Fertilizer 10-10-10
- The best for trees and shrubs: Vigoro Tree, Shrub, and Evergreen Plant Food
- The best for flowers: Osmocote Flower & Vegetable Smart Release Plant Food
The best for lawns
The balance between a healthy green lawn and one that grows so quickly it must be mowed too often is a fine line, but Lesco 16-4-8 Polyplus Fertilizer with Iron will help you find that line.
The most popular lawn fertilizers contain a huge percentage of nitrogen that causes grass to quickly turn green. While we all love quick results, too much nitrogen applied at the wrong time can burn the grass, cause undesirable quick growth that weakens the root system, or actually cause the nitrogen to be washed away and depleted. A fertilizer mix like 16-4-8, when applied as recommended during the growing season, will provide steady nutrients to keep the grass healthy throughout the year.
Lesco 16-4-8 Polyplus Fertilizer with Iron is a slow-release formula that also includes three percent iron for improved color when applied at the start of the growing season in early spring. It is a dry, granular formula that should be applied with a broadcast spreader for even distribution. Each 50-pound bag covers 10,000 square feet of lawn.
Pros: A well-balanced fertilizer that promotes grass root growth.
Cons: It does not work quickly to turn grass bright green and has no weed control. The bag can also spill easily.
$38.97 from The Home Depot $77.70 from Amazon
The best for indoor plants
Unless you have decided to specialize in orchids or cacti, which can be super picky, Osmocote Indoor Outdoor Organic Plant Food will make houseplants from ferns to fittonia healthy and lush.
Okay, not even Osmocote can promise spectacular plants if you overwater, underwater, or don't provide the correct amount of light. But it will give your plants the nutrients they need in a slow-release formula that feeds for six months.
According to the experts at Iowa State University Extension, houseplants should only be fertilized during the growing seasons of spring and summer, so one application is all you'll need per year.
Osmocote is a well-balanced 15-9-12 blend of nitrogen, phosphorus, and potassium. Since it releases slowly as the plant is watered, it will not burn the roots or cause the plant to shoot out gangly growths too quickly.
I use Osmocote on both my indoor potted plants and my outdoor container gardens. The two-pound container covers 75 square feet of soil — and that's a lot of potted plants. I particularly like that the sealed container prevents clumping and is easy to store from season to season.
Pros: Slow-release formula will not burn plants and only one application is needed for the growing season. Plus, the container is easy to store between seasons.
Cons: Not ideal for orchids or cacti.
$11.99 from Ace Hardware $7.59 from Amazon
The best for vegetable gardens
If you're hoping for a plentiful harvest of big juicy tomatoes, crisp beans, and tender lettuce, then you're going to need a solid overall fertilizer like Hyponex All Purpose Fertilizer 10-10-10.
Vegetable gardens mainly need phosphorus and potassium to yield produce. Following the advice of Texas A&M experts, you should not use lawn fertilizers on gardens. They contain too much nitrogen and will often produce plenty of green leaves, but fewer vegetables. They also frequently contain weed control chemicals that can kill plants.
Experienced vegetable growers know that the most important time to fertilize is before you put the first plant or seed in the ground. By working the fertilizer into the soil as you prepare for planting, you'll get an even distribution for seeds and less potential burning of delicate seedlings. If you decide to add additional fertilizer during the growing season, it should be placed at least four to six inches away from the base of the plants and watered in well to prevent burning.
Hyponex 10-10-10 is a quick-release formula that begins to feed immediately, making it perfect for vegetables whose growing season is short. Because it is quick-release, you will need to reapply after 30 days if you have a long growing season.
The dry, granular fertilizer is easy to spread and it does not contain any weed control chemicals that could harm plants. The 40-pound bag will easily take care of feeding an average-sized home garden for the entire season.
Pros: A balanced fertilizer with no weed control chemicals and a fast-release formula.
Cons: You'll need to reapply multiple times for plants with long growing seasons.
The best for trees and shrubs
Even a sturdy oak needs nutrients, and Vigoro Tree, Shrub, and Evergreen Plant Food is the perfect choice for all the woody plants in your landscape.
Applying fertilizer when a plant is getting established will help speed its growth. A slow-release formula like Vigoro is an excellent choice for months of feeding. Take a look at the tree or shrub each year for signs of poor growth. If the leaves are pale, dropping, or little growth has occurred, it may need a boost of nutrients from fertilizer.
The trees and shrubs that are usually most in need of nutrients are those that are in planting beds. If you have trees in the center of a fertilized lawn, they don't need any boost. The roots are absorbing nutrients from the lawn fertilizer applications.
There are liquid, spike, and granular fertilizer applications for trees and shrubs. Liquid fertilizers are sprayed on the leaves of shrubs, but I never feel like they really reach the interior of the plant. Following the advice of the University of Massachusetts horticulturists, I avoid solid fertilizer spikes because the entire root system does not receive an equal distribution of nutrients.
Instead, my preferred formula is granular because it allows me to control the amount of product used per circumference of the plant better. After spreading the Vigoro granules, I water in the nutrients. Since the roots are mainly in the first 12 to 14 inches of soil, I will often apply Vigoro right before some rainy days so I am sure it is going deep into the soil.
The 3.5-pound bag of Vigoro Plant Food will cover lots of landscape since you use only one tablespoon per square foot under the tree or shrub. I apply it in late summer or early fall so that the nutrients are well-absorbed into the root system to help with spring growth.
Pros: It's easy to apply and can be distributed well to reach every area of the root system. It also comes with a 180-day full-refund guarantee for peace of mind.
Cons: It must be watered in to be effective at all.
$5.98 from The Home Depot $5.98 from Amazon
The best for flowers
I've grown beautiful annuals and perennials from peonies to petunias year after year with the help of Osmocote Flower and Vegetable Smart Release Plant Food.
I still use Osmocote today because it's hard to argue with success. Osmocote provides the proper mix of nutrients that plants need to produce showy flowers within a short amount of time. The 14-14-14 ratio provides the right balance of nitrogen, phosphorous, and potassium that plants need for that burst of growth. Some fertilizers recommended for flowers add a higher level of phosphorous which is not usually necessary. Excess phosphorous (and potassium) can enter our water systems through garden runoff causing excess growth of algae bloom that threatens water quality.
Because I'm a bit of a lazy gardener, I have huge beds of blooming perennials, or plants that come back every year. I do supplement with some annuals for quick color in strategic spots. Osmocote feeds them all perfectly and my perennials have thrived to the point that I can divide and share them with friends and family.
Because it is slow-release, I only need to feed once after the danger of frost has past and it easily lasts for four months, or the entire growing season.
Pros: Easy to use, its slow-release formula allows it to last all growing season. It also comes in a sturdy container handy for storage.
Cons: Not recommended for flowers or vegetables grown in containers.