The 5 Best Fertilizers for Petunias

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Not all fertilizers are created equal. The difference between the best ones out there and an average one 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 products 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 products have high price tags.

Here are the top products that we recommend

Comparing Our Top 3 Recommendations

At A Glance

These are the products that we recommend. They use quality ingredients and are much better than the others that are on the market. Please keep reading below to learn more about each one. 

Healthy petunias require proper fertilization for optimal growth

Best Fertilizers for Petunias

Osmocote Smart-Release Plant Food Flower & Vegetable

Osmocote petunia fertilizer will allow for robust roots

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 ideal. This will encourage good foliage and flower growth. It also contains all the necessary micronutrients including boron, copper, iron, manganese, molybdenum and zinc.

Osmocote’s product is a granular feed. 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 product will help you have successful and vibrant blooms.

Mix the granules well into the soil around the base of your plant. Water 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.

Dr Earth Premium Gold All Purpose Nutrient

Dr. Earth fertilizer has proper nutrients for beautiful blooms

Dr. Earth Premium Gold All Purpose Nutrient 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.

It is made sustainably by a company in the USA. It’s founder, Milo Shammas, is dedicated to making a product that not only uses quality ingredients, but also is created in a way that makes a positive impact on the world and environment.

Mix the granular nutrients in the soil around the stem. Make sure that right after you apply it, you give your plant 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.

J R Peters Jacks Classic All Purpose Plant Food

Jacks classic fertilizer has ideal N-P-K ratio for adequate growing

J R Peters Jacks Classic All Purpose Fertilizer is an excellent choice for a water soluble nutrient mix. 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 healthy blooms. It contains micronutrients such as boron, copper, manganese, iron, molybdenum, and zinc. It 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 nutrients, mix it and then pour it right at the base of the main stem.

Best petunia fertilizers are quite different from normal fertilizers

Shultz All Purpose Plant Food Plus

schultz liquid fertilizer provides nutrients to the roots

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 nutrient is easy to apply. All you have to do is add a few drops to the medium at the base of your plant and the it will continue to work for an extended period of time. For this reason, I particularly like Shultz product for when you are planning to grow in containers. The concentrate will rest in the medium and every time you water your plant (or when it rains) the nutrients will be further distributed to the roots. When applied correctly, you will see great vibrant blooms. You will love how easy and it is to apply.

Triple 10 All Purpose Liquid Fertilizer

Triple 10 fertilizer can be used for a range of plants including petunias

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. It has a 10-10-10 N-P-K ratio, which works well with petunias. The Triple 10 product 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 it, pour it right at the base of the main stem. 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.

Petunias require proper care and sun to grow

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 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 have large-flowered blooms. 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 of care or you can also look at our more extensive petunia care guide.

Robust flower growth is a result of proper watering and micronutrients

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 ideal time to transplant 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. 

Healthy petunias are in a planter

Planting

Plant your petunias at least one foot apart from each other. They 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 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.

With proper N-P-K ratio, petunias will flourish

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 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 nutrients 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, apply 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 products 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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