The 5 Best Fertilizers for Petunias

Not all fertilizers are created equal. The difference between the best fertilizers out there and average fertilizers is drastic. It can mean the difference between healthy, vibrant petunias and scarce, lifeless petunias.

Petunias are some of the most popular flowers found in gardens…and for good reason! They are easy to grow and beautiful to look at. However, there are tons of fertilizers on the market. Way too many. And a lot of them simply have wrong nutrient ratios or use poor quality ingredients. On top of that all, the quality of the fertilizer is often not correlated with its price. Plenty of poor quality fertilizers are expensive. I have compiled a list of the best fertilizers for petunias.

Here are the best petunia fertilizers that that we recommend

Comparing Our Top 3 Recommendations for Petunia Fertilizers

The Best Petunia Fertilizers

These are the best fertilizers for petunias. They use quality ingredients and are much better than the other fertilizers on the market. Please keep reading below to learn more about each one. 

Best Fertilizers for Petunias

Osmocote Smart-Release Plant Food Flower & Vegetable

Osmocote Smart-Release Plant Food Flower & Vegetable is THE fertilizer that we recommend for petunias. It has a balanced N-P-K ratio of 14-14-14, which is perfect for petunias. This will encourage good foliage and flower growth. It also contains all the necessary micronutrients including boron, copper, iron, manganese, molybdenum and zinc.

The Osmocote fertilizer is a granular type of fertilizer. They have developed a special granule coating that they call smart-release granules. These smart-release granules permit water to enter and dissolve the encapsulated nutrients. The nutrients are then slowly released over an extended period of time as temperatures change and as more water is applied. More nutrient is released during warmer growth periods. This fertilizer will help you have successful and vibrant blooms.

Mix the granules well into the soil around the base of your petunia. Water your petunia after application so that the granules are not blown away by the wind. Try not to let the granules touch the plant itself as this may lead to plant burn.

CHECK AVAILABILITY: Osmocote Smart-Release Plant Food Flower & Vegetable

Dr Earth Premium Gold All Purpose Fertilizer

Dr. Earth Premium Gold All Purpose Fertilizer uses completely organic ingredients. It contains no synthetic chemicals or toxic ingredient. It is made from human and feed grade ingredients and is enriched with minerals, proteins, carbohydrates, humic acids, and trace elements. It contains not only the necessary macronutrients, but also the correct micronutrients. It has a great N-P-K ratio for petunias.

The fertilizer itself is made sustainably by a company in the USA. It’s founder, Milo Shammas, is dedicated to making a product that is not only great for petunias, but also is created in a way that makes a positive impact on the world and environment.

Mix the granule fertilizer in the soil of the petunia around the stem. Make sure that right after you apply it, you give the petunias a good watering so that the fertilizer is not simply blown away by the wind. Try not to let the granules with the plant itself.

CHECK AVAILABILITY: Dr Earth Premium Gold All Purpose Fertilizer

J R Peters Jacks Classic All Purpose Fertilizer

J R Peters Jacks Classic All Purpose Fertilizer is an excellent choice for a water soluble fertilizer. It’s N-P-K ratio of 20-20-20 works well with petunias. Furthermore, it has all the necessary micronutrients to help supports the growth of a healthy petunia with great blooms. It contains micronutrients such as boron, copper, manganese, iron, molybdenum, and zinc. The fertilizer itself is made from raw materials, which means that it dissolves faster and leaves less of a residue on your soil.

Tip for application: When you are applying water soluble fertilizer, mix the fertilizer and then pour it right at the base of the main stem of your petunia.

CHECK AVAILABILITY: J R Peters Jacks Classic All Purpose Fertilizer

Shultz All Purpose Plant Food Plus

Shultz All Purpose Plant Food Plus is a great choice for petunias. It carries a higher phosphorous content which encouraged good blooms. Fertilizers that are too high in nitrogen content will encourage excessive foliage growth at the expense of better blooms. This liquid fertilizer is easy to apply. All you have to do is add a few drops to the medium at the base of the petunia and the fertilizer will continue to work for an extended period of time. For this reason, I particularly like this fertilizer for petunias grown in containers. The concentrate will rest in the medium and every time you water the petunia (or when it rains) the nutrients will be further distributed to the roots. When applied correctly, you will see great vibrant petunias with good blooms. You will love how easy and it is to apply.

CHECK AVAILABILITY: Shultz All Purpose Plant Food Plus

Triple 10 All Purpose Liquid Fertilizer

Triple 10 All Purpose Liquid Fertilizer contains a balance of nutrients, amino acids, and seaweed extract that help to elevate soil quality and nourish your petunia. The fertilizer is has a 10-10-10 N-P-K ratio, which works well with petunias. The fertilizer comes in a well-designed pour bottle that makes it easy to measure and pour. It is made by Pendelton Turf Supply, which is a company based in the US that has been in business for over 25 years. They create quality fertilizers for plants and lawn and are a reputable company that has great customer service.

Similar to above, when you are applying the fertilizer, pour it right at the base of the main stem of your petunia. Try to avoid getting too much of these water mixes onto your plant leaves as it can potentially cause leaf burn. Apply directly to the soil.

CHECK AVAILABILITY: Triple 10 All Purpose Liquid Fertilizer

Petunia Care and Growing Guide

Petunias are among the most popular flowering plants. They add a vibrant and bright bloom that lasts from spring until frost. While they are in bloom, they release a lovely fragrance.

There are hundreds of different petunia varieties. They come in all types of colors and also are split into two distinct categories – grandiflora and multiflora. As you might infer from the name, grandiflora are petunias that bloom into larger flowers. Multiflora, on the other hand, produce a greater number of smaller flowers. Both can be beautiful when planted in the right places.

Petunias do well, whether they are show-cased in a container or in the garden. They are easy to look after and a true eye-pleaser.

Keep reading below for some of the basics for petunia care or you can also look at our more extensive petunia care guide.

Starting from Seed vs Transplanting

It is much easier to grow petunias as transplants. It can be much harder to grow from seed. If you do attempt to grow from seed, it is recommended that you grow indoors for the first 10-12 weeks. Give them plenty of light through a south-facing window (and maybe supplement with a grow light) and also plenty of water. When they have three leaves, they are ready to be transplanted outside.

The best time to transplant your petunia is in early spring or during the last spring frost. You can check out the ncdc site and click on your state pdf. Go to your city/count and look at the middle row (32 degrees) and at the 50% probability for Spring, and that will give you a rough idea of when you should plant. It doesn’t need to be perfect and is not a science. Just use it as a general guide. 

Beautiful, healthy petunias

Planting Petunias

Plant your petunias at least one foot apart from each other. Petunias need at least 5 hours of full sunlight to grow healthy. They do even better if they can receive full sun all day. The less sun they receive, the less flowers they will produce.

The soil that you plant your petunia in should drain well. It is always helpful to spread organic matter, such as compost or manure, to help with growing your petunia. Spread 2-3 inches of organic matter if you will be using it. Incorporate it into the soil using a garden fork or tiller.

If you will be raising petunias in containers, it is best to use a soil-less mix. This ensures that the medium drains quickly so that the

Water When Soil Dries Out

Petunias are heat tolerant and do not need to be watered frequently. In fact, it is better to wait until the soil dries out before watering again. Usually, this means that you can water them thoroughly once per week. We recommend using soaker hoses. During long periods of drought or extreme heat, you may need to increase water frequency just a little bit.

If you are growing petunias in containers, you also might need a slightly more frequent watering schedule. Again, use the dryness of the soil as a guide. Some people even use the weight of their container as a guide.

Overwatering is the main reason that petunias die. When you over water, it can result in root disease. Water regularly, but let the soil dry out between watering.

Use a 1-1-1 Fertilizer

Fertilize your plants monthly to ensure good growth. Use a fertilizer with an N-P-K ratio of roughly 1-1-1. Avoid using fertilizers that have higher nitrogen components than 1-1-1. Too much nitrogen will encourage foliage growth rather than floral growth. In fact, if you don’t have many flowers, you may want to apply a fertilizer that is even lower in nitrogen content.

For double-flowered varieties, use fertilizer even more frequently such as biweekly.

Bottom Line

Again, I recommend buying the Osmocote’s fertilizer. Don’t make the mistake of buying any average fertilizer at your local gardening store. Many of them will simply not produce the same results. You cannot go wrong with any of the fertilizers above. 

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About the author: Carley Miller is a horticultural expert at TheGreenPinky. She previously owned a landscaping business for 25 years and worked at a local garden center for 10 years.

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