What is the Best Fertilizer for Petunias

best fertilizer for petunias

Petunias are the most widely grown flowers because they are easy to grow and are soothing to the eyes. It is a decorative element that can be grown in hanging baskets, window boxes, and at the corners of your lawn.

Gardening might seem easy but it is no less than a mission owing to the ever changing climate and the inconsistency of availability of essential nutrients in the soil. Same is the story of growing petunias and unlike your imagination, the journey might be tricky without any help.

Therefore, it is highly recommended to find help which is none other than using petunia fertilizers for a promising gardening experience.

The market is filled with an abundance of petunia fertilizers, but not all are worth the money. Several of them do not contain the rightful ratio of nutrients and might lag in quality.

Our team has tested various petunia fertilizers and derived a list of the best fertilizer for growing petunias.

Best Fertilizer for Petunias

Petunias requires a balanced fertilizer label that contains an equal NPK ratio which means it should have equal amounts of nitrogen, phosphorus, and potassium to ensure healthy petunias plantation. The best options are discussed as follows.

1. Osmocote Smart Release Plant Food

petunia fertilizer

Osmocote smart release plant food is an all-in-one granulated fertilizer with a slow release feature to make sure your petunias get the best of osmocote’s amazing nutrients. The multi purpose granular fertilizer has a balanced NPK ratio of 14-14-14, along with 11 essential micronutrients that best mix in water and slowly feed your petunia gardens.

The most unique part is its encapsulated nutrients that first get dissolved in water and then slowly fertilize petunias. The fertilizer works for indoor, outdoor, and even container plants during all seasons.

Furthermore, it ensures a healthy foliage and vibrant blooms of all flowers with its unique formula including 11 essential nutrients. When used in smart quantities as directed, the chances of it to burn your petunias are nil. This all-rounder plant food secured the top pick of our list that feeds for up to 6 months.


  • 8 lb. Indoor and outdoor plants formula with 11 essential nutrients
  • Feeds up to 6 months
  • Slow release fertilizer
  • No-burn possible when used carefully
  • Suitable for all plants, and in all growing conditions
  • Contains balanced NPK value of 14-14-14


  • The balance NPK ratio best encourage good foliage and flower growth
  • It contains 11 essential nutrients including copper, iron, and zinc.
  • These are special granules coating known as smart-release granules that permit water to enter and dissolve the other nutrients


  • Upon letting the granules touch the plant itself might lead to plant burn

Tester’s Verdict

The team observed healthy petunias growth with beautiful blossoms in all conditions as the Osmocote claims. However, care must be taken for the quantity used or else the petunias produced might burn if used recklessly. The team chose this a top pick owing to its smart-release formula and the resulting petunia blooms were amazing.

2. Lilly Miller All Purpose Planting And Growing Food

fertilize petunias

Lilly Miller all purpose planting is available in 4 lb. pack size with a balanced NPK ratio of 10-10-10 that will be best for the growing season. It contains all natural ingredients that will ensure a lush and steady growth of petunias.

The concentrated ingredients are capable of producing results within 1 week of application, according to the reports.

The ingredients in the fertilizer are concentrated that are slowly released to quickly act for the growth of productive plants in minimum time possible for a lush and consistent feeding to your beloved petunias. The product is capable of wonders producing beautiful and appealing gardens.


  • 4lb. All Purpose Fertilizer
  • Slow Release fertilizer For Lush and a consistent Growth
  • Concentrated, Fast-Acting Ingredients
  • All natural ingredients
  • Contains balanced NPK value of 10-10-10


  • It is capable of producing results within one week
  • It is an incredible all- rounder fertilizer that ensure proper and healthy growth


  • The fertilizer is capable of causing burn to the plant if used recklessly

Tester’s Verdict

The testers found the results quite appealing with a healthy garden and strong roots. The trick they observed was regular watering and careful application of the fertilizer. If not carefully applied, the plant burns owing to the high phosphorus content so careful application is the trick.

3. Jack’s Classic Petunia Feed

fertilizer for petunia

Jack’s classic petunia feed is best suitable for plants that are deficient in iron and lacking in green color. Your iron-hungry petunias will quickly get the essential macro nutrients and will get the green foliage that you’d love.

The water soluble plant food is great for hard water. This implies that the water contains high mineral content containing calcium and magnesium carbonates but lacks other essential nutrients that your petunias might require.

The formula is lower in phosphorus than other fertilizers with the NPK ratio of 20-6-22. The Jack petunia feed is reportedly most effective in hanging baskets and containers that you water regularly for effective operation of this water soluble petunia fertilizer.


  • Contains water soluble plant food
  • 20-6-22 NPK value
  • Contains essential micronutrients
  • Best for iron hungry plants


  • Jack’s petunia feed is especially effective in hanging baskets and containers that are watered often
  • The enhanced micronutrient package will produce healthy plants in any growing condition


  • The cost is high for merely 1.5 lb. pack

Tester’s Verdict

The team noticed a growth of petunias with a healthy foliage. They pointed out that the cost is high but the impact for petunias in hard water was wonderful, so highly recommended.

Note: click here if you want to know the 7 Best Lawn Fertilizer

4. Miracle-Gro Bloom Booster Flower Food

best petunia fertilizer

With the NPK value of 10-52-10, the miracle gro flower food is best for better and more colorful blooms. The bloom booster flower food, as the name suggests, is best for providing perfect growing conditions for your plant’s growth. The Miracle gro fertilizer works best for all blooming plants, during all seasons.

Miracle gro is a water soluble formula containing optimal nutrition offers fast-acting results for miraculous and abundant blooms production.

It will not burn or have any undesirable impact on your petunia garden when used as directed. Feed your plants with this formula every two weeks and enjoy a perfect garden.


  • Water soluble, quick release formula
  • Suitable for all blooming plants
  • 10-52-10 NPK value
  • Will not endanger or burn petunias if used as directed
  • Effective and easy to use


  • All you need to do is mix this water soluble product in watering can and water your plants
  • High phosphorus quantity works best for newly planted petunias


  • You will have to repeat the process of fertilizing petunias every 2 weeks
  • The quantity has to be strictly as instructed or it may burn

Tester’s Verdict

The team observed an increased growth in petunias with a healthy foliage. However, the high phosphorus content is capable of burning if not used as directed but this can be avoided easily.

5. Southern Ag All Purpose Granular Fertilizer

fertilizing petunias

Southern ag is an all-purpose granular fertilizer, as the name suggests, is capable of satisfying all nutritional requirements of all types of plants. The southern ag fertilizer contains balanced NPK content of 10-10-10 and other micronutrients in homogeneous and equivalent quantities.

If you are planning on gardening new petunias then this granular fertilizer will do wonders for you with its carefully devised formula including all required nutrients.

It comes in a 5 pounds size bag containing balanced homogeneous plant nutrients suitable for all plant types, so it is highly recommended to get this amazing fertilizer for your growing plants.


  • Granular fertilizer
  • 5 lb. size bag
  • Contains balanced amount of NPK content: 10-10-10
  • For all types of plants


  • The ideal NPK ratio makes it best for fertilizing petunias and other flowering plants
  • This is a all purpose plant food having all nutrients that will keep your plants happy


  • Phosphorus content is high which can be dangerous for neighboring water bodies
  • You must keep your children away because this formula is dangerous for health and environment

Tester’s Verdict

The team observed an interesting growth rate for not just petunias but all flowers bloom flawlessly. However, the formula is injurious to health with its high phosphorus content so make sure to keep away from children.

6. Dr. Earth Flower Garden Fertilizer

petunia food

Dr Earth flower garden fertilizer is strictly made from natural and organic ingredients derived from plants and animals feed. The formula uses no synthetic or artificial ingredients and contains additional beneficial microbes.

The quick-release granular fertilizer is capable of providing nutrients quickly to the petunias for a rapid impact. The NPK ratio of 4-8-4 is best for the quick and healthy growth of your flowers and accounts for quick blossoming during all seasons.

The 100 percent natural fertilizer is easy and simple to apply but the written directions must be followed for the rightful quantity and care. The flower garden water soluble fertilizer contains all purpose plant food for an impeccable result.


  • Granular, Organic formula
  • Contains necessary micronutrients
  • Quick-release formula
  • 4-8-4 NPK ratio
  • Easy and simple application


  • When used in appropriate quantity as directed, the fertilizer is a people and pet safe formula
  • It is a 100 percent natural and organic fertilizer with reportedly amazing results


  • The high phosphorus quantity can be unfriendly to the environment

Tester’s Verdict

The results observed were impeccable as claimed by the company but, the team believes that the phosphorus quantity is capable of causing drastic impacts to the environment if not used as directed.

7. EZ-Gro Flower Food

fertilizer for petunias in pots

EZ-gro flower food is a liquid fertilizer with the NPK value of 10-20-30 for all plant types. The plant food instantly supplies specific nutrients to allow for a healthy and quick growth of your petunias. It is best to use this high phosphorus fertilizer during the bud stage of petunias and the same will increase the number and size of blooms.

The instant feed will also deliver additional micronutrients for best results. Feed your petunias every 7-14 days to ensure a consistent feeding.

The best part is that it is perfect for both indoor and outdoor petunia gardens and instantly supplies your petunias with important plant nutrients, especially phosphorus which is critical during bud stage.


  • Liquid fertilizer having fast-Acting formula
  • 10-30-20 NPK value
  • Contains desirable micronutrients
  • Feed every 7-14 days
  • Suitable for both indoor and outdoor petunias plantation


  • The petunia fertilizer contains high phosphorus content that is important during bud set period
  • It contains several significant micronutrients that will instantly mix in water and ensure healthy growth


  • The fertilizer contains high ratio of phosphorus that can endanger the environment

Tester’s Verdict

The team confirms that the liquid fertilizer has everything that the company claims. Only problem is the high ratio of phosphorus which can be avoided when used in quantities as directed.

Note: check out this article if you want to know the Best Fertilizer For Grass

Buying Guide


There are two types of petunias fertilizers available on the market: the granular, and the water soluble fertilizers. The granular fertilizers account for providing essential nutrients over a long period of time and the process is slow. The water soluble fertilizers are quick-acting fertilizers and instantly increase the growth of your petunias. Depending upon your garden’s condition, choose the rightful fertilizer for best results. Dry gardens could use water soluble fertilizers and vice versa for the humid gardens.

Feed Cycle

All petunias fertilizers include feed cycles instructions in the fertilizers labels. Most fertilizers offer feed cycles of 7-14 days. While some may last for a few months and those are usually the granular types. It depends on the condition of your flowers and the instructions written on the fertilizer’s pack


Purpose of using a fertilizer depends on the condition of your petunias. If you are just starting the gardening of petunias then consider the fertilizers that offer high phosphorus content which best helps in maximum blooms and health of your flowers. If your already planted flowers are showing a dull growth then consider buying the fertilizer having equal NPK ratio.

NPK Ratio

NPK ratio is the content quantity of Nitrogen, Phosphorus and Potassium in the fertilizer. The fertilizer containing equal ratio of all three important contents is the best recommended fertilizer for petunias growth.


How Often Should I Fertilize My Petunias?

You should fertilize your petunias every two weeks of the growing season that begins in July for consistent and healthy growth. Also, follow the instructions given on the fertilizer label.

How Do I Know If My Petunias Need Fertilizer?

Petunias require thorough sunlight and when you notice their color dimming, a fertilizer will help in avoiding the problem. If you notice leaves falling, weak stems, and weak buds, time is calling for you to use fertilizers.


Beautiful plants in the garden are always a refreshing and blissful treat for the eyes. Petunias are best known flowers for ultimate decoration of your garden that best serves the purpose. However, gardening is never an easy adventure so using fertilizer can do the magic for you.

The market offers different types of fertilizers for different purposes. Depending on the condition of your petunias, get the best fertilizer as discussed in the article. There are available granular and water soluble fertilizers according to the quality of your garden. So, choose the best accordingly without any further delay.

Johan Perez
Johan Perez is an experienced agriculturalist with over twenty years in the field. He holds a Ph.D. in Agricultural Sciences and has contributed extensively to research on sustainable farming practices. Johan has also written for numerous agricultural periodicals, offering expert advice on farming technologies and methods. In his free time, he enjoys outdoor adventures, which often inform his professional insights into ecological agriculture.

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