Fertilizer for Seedlings: When and how to fertilize?

I had a 3-week-old seedling that I had grown in 75% peat and 25% vermiculite. I transplanted it into a 4″ pot with more peat and vermiculite, resulting in a couple of leaves. But I had a question: Do I need to fertilize the seedling? Should I use liquid fertilizer? Nitrogen only? When do seedlings need fertilizer?

It’s common to have questions when you’re new to gardening. I struggled to choose the best fertilizer for seedlings and went through many recommendations. With experience, I did learn many things. In short, how soon the plant needs fertilizing depends on the type of potting mix you’re using. But to ensure the health of your plants and help them grow, I recommend reading the article.

Fertilizer to Use on Seedlings:

The best fertilizer to use in seedlings is an all-purpose fertilizer that has a balance of nitrogen to phosphorus to potassium. Adding fertilizer for seedlings will help the young plants to grow the root system and healthy leaves. There are different stages of using fertilizer like a water-soluble fertilizer and granular fertilizer is best after the plant matures. 

The following are some tips for fertilizing seedlings:

  • For applying fertilizer to seedlings make sure that they appear stressed. 
  • The seedling does require frequent watering and light.
  • Avoid applying too much fertilizer that will burn the leaves of the plant and damage the seedlings.
  • Applying a fish or seaweed-based fertilizer does provide micronutrients to your plants and will boost the seedling growth.
Fertilizer for Seedlings: When and how to fertilize?

When and how to fertilize?

Fertilizer for seedlings needs to be done at the right time and in the right way otherwise it will have a negative effect on your plants.to get the answer continue your reading.

When to fertilize?

According to some recommendations you need to start fertilizing seedlings when they grow up 3 inches tall and some say to fertilize them when they have first leaves. Dont worry and get confused; these all fall on the same timeline. The leaves of the plants growing by seedlings come mostly when they grow 2 to 3 inches tall.

Adding fertilizer for seedlings you just do not need to know when to fertilize but how to do it which will make it effective as I have explained below continue your reading.

How do you fertilize vegetable and flower seedlings?

You can add fertilizer to your seedlings in two phases such as 

  • At first, while transferring the seedlings into a larger pot from the seed trays you need to apply fertilizer. 
  • The second time you need to apply diluted liquid fertilizer weekly unless the plant is ready for transplantation into the garden. 
  • Adding fertilizer for seedlings does benefit in a very good manner. For example, it is best to use for growing tomatoes and peppers. Following are some phases you need to learn to add fertilizer for seedlings:
Fertilizer for Seedlings: When and how to fertilize?

Phase 1: Fertilizing seedlings when potting up:

After growing one or two leaves then it’s the right time to transfer the Seedling into the parts which is called potting up. You need to fill the container with a good quality potting mix and don’t use seed starting mix. The potting mix does provide more nutrient moisture control drainage to the soil rather than the seed starting mix. The following are the steps for applying fertilizer for Seedlings.

  • First of all, mix the balanced organic fertilizer In A ratio of 4:4:4 and use Earth from casting with the potting mix.
  • Make sure to always use the fertilizer at a lower concentration. For example, if you are directed to use the fertilizer of 1.0 tbsp in every 4 inches bought then you should mix only half a tablespoon for every 4-inch pot. 
  • Remember to add half a tablespoon of Rock Desk with the potting mixture to provide the micronutrients for the maximum health of the Seedling. 
  • At last, put the mixture and fill the pot.
  • Adding potting mix will increase the growth of the leaves and root stem in the new plants. 
  • It will lead to a healthy and protective plant.
Fertilizer for Seedlings: When and how to fertilize?

 Phase 2. Fertilizing seedlings weekly with liquid fertilizer:

In the second phase after 2 weeks of porting the Seedlings into the pot, you need to feed the Seedlings for that you need organic liquid fertilizer as they have high nitrogen value. You need to mix half of the value as suggested into one gallon of water and then feed the mixture to the Seedling. Avoid over-watering conditions. 

The perfect ratio for adding fertilizer is:

  • Alaska Fish Fertilizer (5-1-1). 
  • Jobe’s Organics Plant Food Mix with Biozome (5-2-3)
  • Fox Farm Liquid Concentrate Fertilizer (6-4-4)
  • Neptune’s Harvest Fish Fertilizer (2-4-1) 
Fertilizer for Seedlings: When and how to fertilize?

Other ways to fertilize seedlings:

There are many other ways to fertilize the Seedling such as:

  • You can apply occasional feeding by using foliar spray. 
  • Add a mild dose of fish and see with fertilizer.
  • You can also compost tea or kelp liquid in water.
  • Fill all the solutions in a spray bottle. 
  • Now you need to take the Seedling outside and for the solution on the Seedling. 
  • Need to remember to spray on both sides of the leaves. 
  • The nutrient is observed by the leaves. 
  • The solution will help you robust the growth of the Seedling. 

The best fertilizers for seedlings

The right way to use fertilizer for seedlings is to mix in a balanced ratio or use a fertilizer that has higher nitrogen and potassium values such as 5-2-3, or 3-1-2. Dont use the granular fertilizer I will suggest you use liquid fertilizers in this stage. if you do it in the right ratio then you will see new development of new leaves, forming root system, height increase, and color changes in leaves i.e. from light green to darker lush green

According to my choice, I will suggest you use organic fertilizers in a 4-4-4 ratio. The following table shows other options for the best organic fertilizer for seedlings:

Best organic fertilizers for seedlings

Buy on Amazon(USA)Buy on Amazon(UK)Buy on Amazon (Canada)
1Jobe’s Organic All-Purpose Granular Fertilizer 4-4-4Miracle-Gro Performance Organics Plant FoodJobe’s Organics All-Purpose Granular Fertilizer
2Dr. Earth Premium Gold All-Purpose FertilizerGroundMaster Flower & Vegetable Organic Plant Food CompoundGaia Green Organic 4-4-4 All-Purpose Fertilizer
3Burpee Natural Organic All Purpose Granular Plant Food 4-4-4Vitax Calcified SeaweedPro-Mix Organic Tomatoes, Vegetables & Fruits Garden Fertilizer
Fertilizer for Seedlings: When and how to fertilize?

Best liquid Fertilizers for seedlings

Buy on Amazon (USA)Buy on Amazon(UK)Buy on Amazon (Canada)
1Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1Envii Seafeed Xtra – Organic Liquid Seaweed FertiliserNeptune’s Harvest Fish & Seaweed Blend Fertilizer 2-3-1
2Neptune’s Harvest Fish Fertilizer 2-4-1Maxicrop Original Seaweed Extract, Organic Plant Growth StimulantNeptune’s Harvest Hydrolyzed Fish Fertilizer 2-4-1
3Liquid Kelp Organic Seaweed ExtractOrigins Organic Plant FoodNeptune’s Harvest Liquid Seaweed Plant Food

Tips for fertilizing seedlings:

  • Do follow all the directions that are written on the package of the fertilizer for the container and the direction may vary from brand to brand. 
  • Always use less than the amount mentioned on the fertilizer as there is a high risk of burning of Seedlings if you use more fertilizer which may cause death. 
  • Never use fertilizer on stressed seedlings. 
  • You need to water the seedlings frequently to make sure they don’t dry out. 
  • Using fertilizer will help in the growth of the Seedling and at this point, water is an important component. 
  • With water, you need to provide the Seedling good amount of light which will be beneficial for the Seedling. 
  • Many organic fertilizers consist of bone meal, blood meal, or fish products that may smell really hard so in that case you can apply the fertilizer outdoors so that the smell does not hit bad. 
  • You can provide the seedlings some amount of air by leaving them outside for a few hours and bringing them indoors after evening. 
  • The smell can also attract the cats and the dogs at your home so keep the Seedling away from the pets so that they won’t harm the Seedling. 
  • After the Seedling is transplanted into the garden the nutrient requirement in that case is different so do follow the vegetable Garden fertilizer schedule instructions that are written on the package of the fertilizer.


Hence after reading this article, I hope you have got all your answers related to the fertilizer for Seedlings. Make sure to follow all the instructions that are mentioned on the package but use a useless amount of fertilizer and regular watering of the Seedling.

Becky Decker

Becky Decker, our esteemed Editor-in-Chief, is a passionate gardener with years of experience in the world of horticulture. With her guidance, BonjourGreen.com aims to be your trusted companion on your gardening journey. Featured In   Becky Decker’s expertise and gardening wisdom have been recognized and featured in various prominent publications, including:   Homesandgardens.com Yahoo.com Urbansplatter.com Inkl.com Foliagefriend.com Yahoonews  Experience & Background   Becky Decker’s love for gardening has been a lifelong journey. She has honed her skills through countless seasons of planting, nurturing, and harvesting a wide variety of plants, flowers, and vegetables. Her deep-rooted knowledge is complemented by her Bachelor’s degree in Horticulture from the University of Green Valley.   Prior to leading BonjourGreen.com, Becky worked as a garden consultant, helping countless individuals turn their outdoor spaces into vibrant, thriving gardens. Her experience spans over a decade, making her a trusted authority in the gardening community.   The Birth of BonjourGreen.com   Inspired by her passion for gardening and her desire to share her expertise with a wider audience, Becky Decker launched BonjourGreen.com in 2021. This platform serves as a hub for gardening enthusiasts of all levels, from beginners to seasoned pros.   At BonjourGreen.com, we are committed to providing you with comprehensive guides, expert advice, and hands-on tips to help you achieve success in your gardening endeavors. Whether you have a small balcony garden or a sprawling backyard paradise, we have the information you need to make your garden flourish.   Our Mission   BonjourGreen.com is more than just a gardening website; it’s a community of gardeners who share a common love for nurturing the Earth. Our mission is to empower you with the knowledge and resources to create beautiful, sustainable gardens that bring joy and tranquility to your life.   Join Us on This Green Journey   We invite you to explore BonjourGreen.com and embark on your gardening journey with us. Whether you’re seeking advice on planting techniques, pest control, landscaping ideas, or the latest gardening trends, you’ll find it all right here.   Connect with us, ask questions, and share your gardening stories. Together, we’ll cultivate a thriving community of gardeners and help each other make the world a greener, more beautiful place.   Let’s dig in and grow together at BonjourGreen.com, where gardening dreams bloom!

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