5 BEST Plant Fertilizers of 2021 [reviews]

When you’re looking to grow your plants in a way they will thrive, there is no shortage of synthetic fertilizers out that at home improvement stores. In order to have the most vibrant, healthy plants, you need plant fertilizer.

The vast selection of plant fertilizers out there can be intimidating, so I’ve gone ahead and done the hard work for you and put together a list of the five best plant fertilizers based on my personal experience, 40 hours of online research, and the knowledge I gained from my 20 years in the landscaping industry.

At a Glance – Our Top Picks.

Top 5 Plant Fertilizers – Reviews

Ready to check out my top picks for best plant fertilizers? Don’t forget to check out some helpful tips in the buyer’s guide.

1) Super Compost Organic Plant Food

Soil Blend’s super compost is one of my favorite all-around formulas for plants and gardens because it’s safe, it’s eco-friendly, and it works. Compost is how nature fertilizes the soil, by taking the nutrients from dead leaves and other natural debris and breaking it down to recycle. This super compost is a straightforward way to enhance the richness of your soil without the headache of composting yourself. 

You don’t have to spread this compost over your entire lawn or garden area. If you are on a budget, you can pack a little of the mix (you combine this with soil in a 1:4 ratio) around the base of all the plants you want to fertilize. I’ve used this brand and been happy with the results.

Pros:

• Pet and kid-safe
• Eco-friendly
• General-purpose plant fertilizer
• Non-GMO
• Affordable

Cons:

• Must be mixed in with other soil
• Should wear gloves while working with this product

2) Organic Bountea Humisoil

Humisoil is sort of like probiotics for your lawn and garden mixed with additional nutrients. Humus (not to be mistaken with hummus) is similar to compost but isn’t just recycled matter. Humus is composted nutrients, often with beneficial fungus components, that reached the point of stability. 

Humus is full of healthy microbes for your plants and also aids in unlocking nutrients that are already in your soil for your gardens. Humic acid and humus can also help plants become more disease-resistant and retain moisture better. If you have sandy soil around plants, humisoil is one of the best fertilizers to help your plants retain more moisture.

Pros:

• Free of additives and eco-friendly
• Ideal for soils with a lot of sand or clay
• Helps plants retain moisture
• Stabilized organic material
• Pet and family safe

Cons:

• Gets pricey if you need large amounts

3) Azomite Micronized Rock Dust for Gardens

Azomite rock dust is a super-charger for minerals in your soils. Many synthetic fertilizers try to mimic the trace minerals for your plants with artificial or partial components of minerals. Azomite is actual minerals in finely ground rock form, which supply the full spectrum of these nutrients to your plants. Azomite’s mineral blend includes soluble Potash .2 percent, Calcium 1.8 percent, and Sodium .1 percent.

Azomite is sourced from Utah in the United States and is my favorite rock dust that I’ve tried. For gardens, you should apply roughly 3.5 pounds per 10 square feet of area. You can blend this rock dust in with compost or the existing soil around your plants. 

This blend is also one of the best fertilizers for grass to boost mineral content in your yard (you can mix it in with spreadable granules). Make sure you wear a dust mask while working with this product. 

Pros:

• Naturally boosts mineral content of the soil
• Improves plant roots
• Long-lasting
• Ideal for mineral-poor dirt
• Sourced from the USA

Cons:

• Expensive in large amounts
• Dusty to work with

4) Wiggle Worm Industries Builder Worm Castings

Worm castings are not something you might see walking into a big box home improvement store, but this product is one of the best fertilizers because it mimics what you get in super healthy soil. Plentiful Earthworms are a sign of excellent dirt, and worm castings are the result worms producing new, fertile soil with natural fertilizer.

Wiggle Worm is one of my favorite formulas because it is odor-free and is excellent for both indoor and outdoor plants. Wiggle Worm feeds their nightcrawlers nutrient-rich organic materials. One thing I love about this product is that it mimics precisely what naturally happens in your yard and garden. 

You don’t have to worry about animal manure, as Earthworms are already in your lawn and around plants enriching your soil. Wiggle Worm provides an extra boost of the result of that process directly to the root area of any plant you pack it around.

Pros:

• Odorless
• Mimics natural, ultra-rich soil
• For indoor and outdoor plants
• Eco-friendly and organic
• Pet and family safe
• Affordable

Cons:

• In rare cases can attract gnats 

5) Liquid Kelp Extract Seaweed Fertilizer Concentrate

Seaweed formulas, in my opinion, are one of the best fertilizers for tomatoes and other garden plants. These concentrates take the nutrients and minerals from sea plants, in this case, the seaweed Ascophyllum Nodosu from Norway, and deliver them directly to the roots when you mix it with water.

I think of this seaweed fertilizer as a power shot of a super juice for plants. I notice my vegetables growing more prominent and the blooms on my flowering plants looking fuller and more vibrant when I use Liquid Kelp. Seaweed concentrate is another fantastic option for both indoor and outdoor plants. 

Pros:

• Helps plants adapt to environmental stressors better
• Stabilizes chlorophyll and enhances the green color
• Ideal for vegetable gardens
• Can be used as an occasional boost for plants
• Indoor and outdoor use

Cons:

• Can get costly when used in large amounts or often
• Can negatively affect plants if applied too heavily 

Plant Fertilizer – What You Need to Know

When it comes to finding plant food, you might have different criteria for picking a product than you do for your lawn, like me. Especially if you have a bigger yard, fertilizer can get expensive. Add up the number of times you need to put down lawn food in a season, and it can be hard on the wallet. 

Thanks to the square footage needed to cover a yard, I sometimes use synthetic fertilizers. However, with plants, I like to go with a successful product yet also natural as possible. I do this not only for environmental reasons—no need to be hard on the environment when affordable and effective options exist—but also because some natural fertilizers are better for the roots of your plants in the long run.

The same way eating healthy keeps your organs in better condition than junk food, organic compounds that address the health of your soil improve the longevity and root health of your plants more than many synthetic fertilizers. 

How to Fertilize Plants

Start small if you are using a new type of fertilizer. Even with organic compounds, you can “burn” plants or load them with too much of a particular nutrient. If you are using a concentrate such as the Liquid Kelp Extract Seaweed Fertilizer Concentrate dilute it with water more than the instructions indicate to see how your plants handle it.

For compounds such as Organic Bountea Humisoil, you can shake some on the ground surface around plants, mix with another fertilizer such as a little rock dust and fold it into the dirt, or replant foliage with these compost fertilizers mixed into the soil. Reapply as the instructions direct. 

For more info, watch the video below by Backyard Eden.

Address the Root of the Problem for Roots

I highly recommend going with more natural fertilizers for plants and gardens whenever possible. Without chemicals, you have a lot less to worry about regarding the environment and safety for pets and kids. 

Furthermore, I like natural composts because they get to the heart of the issue—the quality of your soil. Over time, if you continue to use products like compost, rock dust, and worm castings, you are building incredibly rich Earth for plants to thrive. 

Get Your Vibrant Garden

Chemical fertilizers wear off, too, but when they do, they don’t leave the ground better than it was before. Natural compounds as fertilizers improve the soil. As you continue to use them, your plants will grow stronger roots, retain moisture better, and will be able to absorb nutrients you put down more and more. Now try one (or a few) of these and watch your plants thrive!