Organic Tomato Fertilizer


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To know what to add to the soil, you must first understand what you are missing!

One of the most common questions we get about growing tomatoes is, “What is the best organic tomato fertilizer to use?” That can be a hard question to answer because the organic tomato fertilizer you use completely depends on the needs of your soil. Anyone who recommends a one-size-fits-all solution for fertilizing tomatoes is not answering the question with the most accurate and sustainable answer.

To know what organic tomato fertilizer you need to add to your soil, you must first get your soil tested. Soil testing kits are available widely, but we recommend a quality test from a reputable lab, such as the laboratory soil tests offered on our website. It’s best to get your soil tested 4-8 weeks before the growing season so that you have time to fertilize correctly.

prepped fertilizer     

Once you know what your soil is missing, you can learn what tomatoes need. You can then add that to your soil, container, or planting mix. The extra step of getting your soil tested may seem like extra work and more money spent. But in the end, you’ll save yourself the cost of unnecessary fertilizer and have the environmental benefit of not overfertilizing.

What nutrients do tomatoes need to thrive?

Your organic tomato fertilizer should have all the necessary nutrients for the production of tomatoes.

Nitrogen: for leaf building

Potassium and phosphorous: for flowering and fruit set

Micronutrients (calcium, selenium, and zinc): add to the plant’s overall health and can contribute to the overall flavor

Beneficial bacteria: These, like the beneficial probiotics we need for healthy digestive systems, ensure that soil life is thriving and contributes to the health of all plants.

Once you’ve identified the essential nutrients missing from your tomato growing area, you can add an organic tomato fertilizer with the appropriate missing components.

What we use on our Farm and in our Garden.

We have been growing for more than a decade in San Diego’s less than desirable soils. Over the years we have learned what the soil needs and loves. Here are our star players in helping our gardens thrive.

Great Big Tomatoes Compost Tea does so much more than add nutrients to your soil. This product adds essential microbiology to containers, raised beds, and in-ground gardens for happy plants. It helps grow the fungal and bacterial links in soil that are naturally missing, particularly when using bagged soil products. We loved the results from this compost tea so much that we now use it whenever we grow tomatoes, whether in the ground or a container! It works great for peppers too! The idea is simple. Great Big Tomatoes Compost Tea works in the same way that we use probiotics for healthy digestive microbiology. It helps soil thrive with all the organisms we can’t see while making nutrients bioavailable to plants.

Neptune’s Harvest Fish Emulsion, a somewhat stinky but oh-so-effective fertilizer, is our go-to in the garden for a host of reasons. We like that it derives from a natural byproduct of the fish industry and helps to use commercial bi-products that would otherwise be wasted. This product is not mined or taken from environmentally fragile areas. Additionally, fish emulsion is very mild, will not burn your plant, and is absorbed by the leaves and roots. This means you can be a bit willy-nilly with applying the fertilizer without concern for burning your plants.

Organic granular fertilizer is essential for adding nutrients back into the soil stripped from gardening over time. We like to use Darn Good Fertilizer because it breaks down slowly, will not burn plants, and is less likely to be washed away. We apply granular fertilizers between growing seasons on our farm to replenish what we have taken out.

How much and how often do you add organic tomato fertilizer?

Fertilizing tomatoes or any crop requires choosing a fertilizer with the nutrients your soil is missing. Next, it’s important to read the product information to know how much to add to your planting. Every fertilizer company, brand, and kind has different recommendations depending on the product’s ingredients. Read the instructions to see the amount of product the manufacturer recommends. Their instructions will provide the most accurate use of the organic tomato fertilizer for your crop.

When do you add organic tomato fertilizer to your crops?

We fertilize at the following times on our farm:

Bed Prep or Before Planting

If soil test results show we lack a particular nutrient, we must add an organic granular fertilizer to our planting area before planting our tomatoes. Add an organic granular fertilizer like our Darn Good fertilizer to the soil in the ground, raised bed, or container where we’ll grow our tomato transplants. This fertilizer is slow to break down and will give a strong nutritional base for the plants to grow from.  Because it is slow to break down, it is good for long-term fertility needs but does not provide the instant boost of nutrition that small seedlings need.  For that we use a liquid fertilizer like our Neptune’s Harvest Fish Fertilizer

fertilizer in seed tray

During the Growing Period

During the first 4–8 weeks of growth, before flowers bloom on the tomato plant, our goal is to allow the plant to grow quickly, happily, and easily with access to plenty of nitrogen for plant growth. As you’ll learn in our tomato growing guide, nitrogen is like the carbohydrate of the plant world and helps to energize plant growth. We use Neptune’s Harvest Fish Fertilizer during the plant’s growing period. This liquid fertilizer is easy for the plant to absorb and can be taken up by the roots and the leaves.  This gives the plant the instant boost it needs! When we are growing our seedlings, we like to use the liquid fish emulsion every time we water at a 50% dilution rate. This allows the plant to grow quickly with robust root systems that will help them transplant better.

We all know the adage that more is not always better. In this particular case, it is very accurate. Adding excessive nitrogen to fuel tomato growth can lead to pest issues like aphids, whiteflies, and other insects. Additionally, you are likely to grow more plants than tomatoes — who wants that? So when using liquid fertilizer or granular fertilizer, always read the directions on the bottle and use what is recommended or less.

At Flowering

Fertilizing at flowering can ensure that your plants have the essential nutrients to grow happy, healthy tomatoes. Nutrients like calcium are important for the prevention of blossom end rot. By adding a fertilizer that contains readily available calcium for the plant at flowering, you can prevent the issue before it arises. It is very hard to stop blossom end rot once you notice it on your tomato plants. Just as we need our vitamins to stay healthy and prevent illness, so do tomatoes.

If you are looking to grow happy and healthy plants this year, make sure you get your Fully Loaded Fertilizer Bundle. All the products you need in one convenient product. Plus, by buying in the bundle, you save!



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