Gardening Growing Tomatoes How To

How to Pick & Use the Best Tomato Fertilizer for Containers

Fertilize your container tomatoes are not the same as your garden tomatoes. There are a lot more issues that will come to you when you are going to feed your potting tomatoes.

Garden tomato plants spread their roots as much as they can to search for foods from the ground. On the other side, container tomatoes get limited space and can’t spread their roots to find foods from the ground.

As a result, your container tomatoes fully depend on you to provide them enough nutrients to grow and produce fruits. So, fertilizing your container tomatoes is a little bit tricky and very important to get a healthy harvest.

In this article, I will tell you some helpful tips to get the best tomato fertilizer for containers and how to apply them for the best output.

Types of Fertilizer for Potting Tomatoes

Tomato plants need different types of nutrients in different stages of their plant’s growth. Usually, you can apply two types of fertilizer for your potting tomatoes such as:

  • Slow-release granular organic fertilizer
  • Liquid or water-soluble fertilizer

How to Apply Granular Slow-Release Organic Fertilizer for Container Tomatoes

Tomato plants are heavy feeders. Besides your container soil may able to preserve a certain amount of nutrients due to space limitation. So, you should use some slow released granular organic fertilizer to feed them longer. 

This fertilizer consists of animal or poultry manure, quality compost, mineral-based ingredients, and other macro and micro additives. It may also vary on the brand you choose. Besides their N-P-K ratio have some variation such as 10-10-10 or 5-10-15 or 5-10-5 or something similar.

However, most of the potting mixes can provide nutrients to your tomato plants around two weeks. After that gradually your potting mix loses its strength but your plants want more nutrients.

So, once you add some additional granular fertilizer in your potting mix it may continue providing nutrients later on. But it releases the nutrients very slowly and some of the nutrients may drain out due to regular watering.

How to Apply Liquid Tomato Fertilizer for Containers

Due to the proper drainage system, the nutrients inside the potting mix may drain out quickly before the plants get them. As a result, only providing slow-release fertilizer for container tomatoes won’t fulfill your tomato plants’ needs. So, you need some water-soluble fertilizer to feed them well.

There are a lot of liquid fertilizers available in the gardening store or online store such as fish emulsion, Epsom salt, compost tea, kelp meal, and so on. 

Start feeding your container tomatoes with liquid fertilizer after two weeks of planting them in pots. Then apply these liquid fertilizers every one or two weeks later based on the plant’s growth. Before using them measure the NPK ration of the fertilizer which should be mentioned on the pack label.

Water-soluble fertilizer feeds the tomato plants quickly than granular fertilizer and your tomato plants can absorb them easily.

However, if you are a creative gardener and have patience then you can make the liquid tomato fertilizer at home and save your money. 

Best Fertilizer Ratio for Container Tomatoes Based On the Growing Stages

Usually, you can fertilize your container tomatoes in three different stages. In each stage, you need to apply a different proportion of fertilizer based on the plant’s growth.

State 1: Before Flowering

From planting up to flowering, tomato plants need to develop their root system, plant stems, and foliage. At this stage, you should apply a balanced fertilizer with a 10-10-10 ratio that can develop the overall plant growth in containers.

Here balance fertilizer means with an equal proportion of NPK where N stands for Nitrogen, P stands for Phosphorous, and K stands for Potassium.

You may find 1-1-1 or 3-3-3 or 20-20-20 or other similar proportion of NPK fertilizer in the gardening stores.

Mulch your container tomatoes with grass clippings. This is a good source of nitrogen that your tomato plants need at the beginning stage of their plant growth. Besides it also keeps your potting soil moisten for longer.

Stage 2: During Flowering

During your tomato plants start flowering they need more phosphorous and potassium to produce flowers. So, at this stage, you need a fertilizer with a 5-10-10 ratio.

However, you should also apply some micronutrients such as magnesium, sulfur, and calcium to your container tomato plants to fulfill the other nutrients deficiency and develop their disease resistance capacity.

Stage 3: During Fruiting

When the tomato plants start setting fruits, they need a fertilizer with a 5-10-15 ratio. Besides you need also to apply a little portion of magnesium, sulfur, and calcium for better results.

Container Tomatoes Need Regular Fertilization with A Little

Both over-fertilization, as well as less fertilization, may harm your tomato plants. Besides, this may also drain out quickly and doesn’t work for a long time.

So, apply liquid fertilizer for your container tomatoes often with a little to get the best output.

Other Reasons That Bias Containers Tomato Fertilization

Container tomato fertilization not only depends on the fertilizer type and quality but also depend on the following factors:

Quality of the Potting Mix

Using good quality potting mix is very important for your container tomatoes. They contain some fertilizer and other helpful additives. Besides it also ensures proper drainage and good aeration system which is very important for container tomatoes.

Tomato Varieties

Usually, determinate tomato varieties are the best suit for containers. And once they start ripening you don’t need to fertilize them anymore. Because they start and finish ripening all at once within two weeks.

On the other hand, if you intend to grow indeterminate tomatoes in containers then you need to continue fertilizing your tomatoes till the end of the season.

Tomato Container Size

Bigger containers hold enough potting soil, more water, and food for tomato plants. So, once you fertilize in large containers, they can hold them for a longer time. 

On the flip side, small containers can hold less soil, water, and food for plants. So, they need frequent nutrients supply then large containers.

Tomato Plant Size

Small tomato plants absorb fewer nutrients. But once they grow up, they need more. Besides dwarf, determinate and indeterminate tomato varieties need a different proportion of fertilizer due to plant height.

Weather Condition

Weather condition plays an important role in the fertilization process.Usually, container soil dries out quickly in hot and dry weather conditions.

So, they need more frequent watering and this may drain out potting soil nutrients. In that case, your tomato plants need more frequent fertilization.  

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John Michael
John Michael is a self-help writer and a hobby gardener. He has a bachelor's degree in Library Science. Michael’s passion in writing is to inspire the beginner gardeners to not just “hang in there” or “make it through” but to thrive. He does this through blogging at ofags.com. He began writing in 2017.

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