I wanted to check what is the best natural fertilizer for container vegetables. Below is a list of the best natural fertilizers I found and how I should use them.
Natural fertilizer is a plant food that contains organic nutrients that have not been processed. They are usually slow-release as the organic matter decomposes in the soil and releases the nutrients.
Eggshells are a good source of calcium for your container plants.
The best way to use eggshells is to powder them and mix them in with the potting soil when starting the plants. You can also spread the powder over the soil which acts as a slow-release fertilizer.
Another option is to leave the eggshells in water for a week and then use the tea as a fertilizer in your container soil.
Coffee grounds are another nitrogen-rich source of natural fertilizer for your container plants. They contain about 2% nitrogen which makes them beneficial for your leafy vegetables.
You should let the coffee grounds dry before using them in your containers. The best way to use them is to apply on the soil as a layer of mulch.
You could also soak them in water for a week and then use the diluted tea to feed the soil in containers.
You can get coffee grounds for free from coffee shops that would like to dispose of them.
Bananas are a great source of potassium for your plants. You can use both the bananas and the peels as a slow-release fertilizer.
The lazy method is to just plant the banana in the soil. You can do better by chopping up the banana peels and mixing it in with the potting soil.
You could also puree the banana or the peels in a blender and pour that over the potting soil in the container.
If you have an aquarium at home, the aquarium water is a good natural fertilizer to use for your container plants.
The aquarium water contains nutrients that are released by decomposing fish waste and fish food. This water is rich in nitrogen that is beneficial for your leafy vegetables.
This method of using the nutrients released by fish is used in a method known as Aquaponics where plants and fish are grown together to create a nutrient delivery cycle.
Just make sure you are using freshwater fish in the tank and not saltwater as that is not suitable for the plants.
Green tea is a rich source of nutrients for your acid-loving plants. You can use one tea bag in two gallons of water.
You can also compost the green tea leaves and use the grounds as a fertilizer.
Cooking water is a good source of nutrients for your container plants. You can use water you boiled eggs, potatoes, vegetables, or pasta in.
Do not use water that is used to cook meat or water that contains salt in it. Cool the water before adding it to your container soil.
Epsom salt can be a good source of magnesium and sulfur for your container plants. You need to dilute a tablespoon of Epsom salt in a gallon of water.
Then spray the mix on your plants and soil every month.
If you have a fireplace you can use the wood ash that collects as a good source of potassium. Make sure the ash does not contain lighter fluid or charcoal as that will harm the plants.
Wood ash works well if you want to increase the alkaline levels of the container soil.
Gelatin is a good source of nitrogen for your container plants. Mix the gelatin with 1 cup of hot water and stir well. Then mix it with 3 cups of water to get a nutrient solution.
You can pour this solution in your container soil every month to give your vegetable plants a dose of nitrogen.
Hair is a good source of nitrogen for your container plants. You can collect your own hair or ask your local barbershop or beauty salon for some.
You can also collect your dog or cat’s hair and that works fine as well.
Matches are a good source of magnesium for your plants. The best way to use them is to soak the matches in water.
Then you can use the tea that forms as a fertilizer for your container plants.
Powdered milk can be used as a source of calcium for your container plants. You can mix this with the potting soil when starting.
Or you can spread the powder over the soil and it will seep into the soil with watering. The plant’s roots will absorb the nutrients from the soil.
Molasses are a good source of nutrients for your plants. It contains a mix of potassium, magnesium, iron, calcium, sulfur, copper, and a ton of other nutrients.
It’s useful for increasing the beneficial microorganisms that are present in the soil. The best way to use this is to dilute it with compost tea and spray it on the soil.
Kelp is not a strong fertilizer as it contains the NPK values of 0-0-1. But it does a great job supplementing other fertilizers.
It helps the plant develop heat and drought resistance and helps protect them from other problems. If the plants are having poor growth and yellowing of the leaves, adding a liquid kelp fertilizer will help.
Alfalfa meal is a natural fertilizer that is made by fermenting alfalfa plants. It’s a good source of nitrogen for your container plants.
Cow manure is a good fertilizer that gives your container plants good nitrogen, phosphorus, potassium, and other nutrients.
You need to use aged cow manure and not the fresh dung as that contains high levels of ammonia that can burn your plants. And it can contain pathogens as well.
Limestone is more of a conditioner than a fertilizer. You can use it in your containers when you want to increase the soil pH levels.
If you are raising chickens, this is a good source of natural fertilizer for your container plants. Or you can get some from your family or neighbors if they are raising chickens.
It’s high in nitrogen and has a good amount of phosphorus and potassium. You need to use aged chicken manure as the fresh ones can burn your plants.
Compost is a great source of nutrients and beneficial microorganisms for your container plants. It usually has a good amount of nitrogen, phosphorus, and potassium.
You can mix compost in your potting soil while starting the container plant. Or you can put a layer of it on the soil once the plants are growing.
Worm castings are another rich source of nutrients and beneficial organisms for your container plants. It is even more potent than compost.
You can get an NPK of 5-5-3 with worm castings which gives a good amount of nitrogen, phosphorus, and potassium for your plants.
Compost tea is a good natural fertilizer you can brew at home. This is made using compost which means the tea contains the beneficial nutrients and organisms found in compost.
You can spray this diluted fertilizer on your container soil and plant foliage as part of your watering schedule.
Just make sure the water you use to dilute the tea is free from chemicals like chlorine found in tap water. Otherwise, you end up killing the organisms in the compost tea.
The fertilizer will still contain the beneficial macro and micronutrients but will be lacking the organisms that could create a healthy environment in the soil.
This is a fertilizer that is made by grinding animal bones into a fine powder. It provides a rich source of phosphorus, calcium, and protein to your container plants.
This is a fertilizer that is rich in nitrogen that makes it suitable for leafy vegetables. You can use it to raise the acid levels in the soil for plants that grow in acidic soil.
Rock phosphate is obtained by mining clay deposits and contains a rich source of phosphorus. You can use it for your fruit vegetables to grow faster and better fruits and flowers.
Fish emulsion is made by using the byproduct of processing fish. It’s the fish waste that is liquefied in a blender.
This is a good source of nitrogen for your container vegetables as it has NPK values of 5-1-1. You can use this natural fertilizer for your leafy vegetables to grow good and healthy foliage.
You can mix the fish emulsion with other fertilizer that is rich in phosphorus for root and fruit growth. And with one that is rich in potassium for overall plant strength and health.
Cottonseed meal is a by-product of manufacturing cotton. It is a rich source of nitrogen and potassium for your container plants.
It helps improve the soil texture and helps build humic acid in the soil.
Granite meal is made by grinding granite rock into a fine powder. This is a good source of slow-release potassium for your container plants.
Why is it important to fertilize container vegetables?
Like all living organisms, plants need nutrients to grow. When you grow the plants in the garden soil, they can spread their roots deep and wide.
This helps them seek out the nutrients and absorb them for their needs. The nutrients in the garden soil get depleted and replenished with the natural cycles that take place in the environment.
But when you grow plants in pots, they are quarantined in how deep and wide they can spread their roots. They are limited in how much nutrients they get from the soil.
The potting soil that is used in containers is mostly sterile. This makes it great for the air, moisture, and nutrients to reach the plant’s roots. But the soil itself does not contain nutrients.
That’s why you need to periodically add these nutrients yourself. And that is the reason to fertilize your container vegetables.
You have to mimic the role of nature and provide your container vegetables with the nutrients they seek out.
There are situations when you should not be using fertilizer for your container vegetables. Most herbs prefer low nutrient conditions and it’s not advisable to add fertilizer to their containers.
If the container vegetables are stressed due to the weather, pests, or diseases, it’s not a good idea to add fertilizer to the container.
What are the benefits of using natural fertilizers for container vegetables?
You can choose to use natural fertilizer or chemical fertilizer for your container vegetables. But I would recommend going with the natural ones.
The natural fertilizers are slow-release as they are based on organic material that breaks down and releases nutrients slowly in the soil. This means your plant’s roots are protected from an overdose of the fertilizer.
When you use a chemical fertilizer, you need to be precise in the amount you need to use. Otherwise, you risk the tender tissue of the plant suffering from chemical burns.
The natural fertilizers contain organic material that breaks down and improves the soil-web structure of beneficial organisms in the soil. The chemical fertilizers provide nutrients to the plant but damage the soil-web structure.
Natural fertilizers are biodegradable and sustainable which makes them good for the environment. Chemical fertilizers don’t have these characteristics making them a bad choice over the long term.
Natural fertilizers improve the soil over the long term and do not leach harmful materials into the soil. When you keep adding chemical fertilizers and watering the plants, the chemicals leach into the soil and eventually make it toxic.
What kind of natural fertilizer should you use for your container vegetables?
To use the natural fertilizer for your container vegetables, you need to know the basics of what the fertilizer contains. The most important components of fertilizer are NPK values.
N stands for nitrogen, P stands for phosphorus, and K stands for potassium. Each of these macronutrients plays an important role in the development of a plant.
Nitrogen is beneficial for the growth of the plant foliage. That makes it a beneficial nutrient for leafy vegetables and herbs.
Phosphorus is essential for fruit and flower development. This makes it a good nutrient to add for your fruit vegetables like tomatoes, cucumbers, and peppers.
Potassium is an important nutrient that develops a strong root system. It’s a beneficial nutrient for your root vegetables like carrots, beets, and radishes.
A balanced fertilizer contains an equal percentage of all three macronutrients. So you can find a fertilizer with NPK values as 5-5-5 which means 5% nitrogen, 5% phosphorus, and 5% potassium.
Depending on which vegetables you’re growing in the container, you can select a natural fertilizer that is high in the particular macronutrient content.
For herbs and leafy vegetables, you can choose a natural fertilizer that is rich in nitrogen. For fruit vegetables, you can choose one that is rich in phosphorus. And for root vegetables, you can choose a natural fertilizer that is high in potassium.
How to use natural fertilizer for container vegetables?
The potting soil that you use for your container vegetables usually will not contain nutrients. This is different from garden soil that contains a ton of organisms and nutrients moving around.
One way you can attempt to mimic nature in your containers is to add compost to the potting soil when planting. This will help the beneficial organisms to move into the container and create a micro soil web.
This helps introduce a natural nutrient cycle in your soil and you will need to add a lot less fertilizer to your container vegetables.
How to apply the natural granular fertilizer
The natural fertilizer you can add to your containers could be granular fertilizer or liquid fertilizer. The granular fertilizer sits in the soil and releases nutrients when the potting soil is watered. This helps release the nutrients as the plants need it.
You can mix the granular fertilizer with your potting soil when you’re starting your containers. Follow the manufacturer’s instructions on how much natural granular fertilizer to use.
If there are no instructions, you can apply a handful to a 5-gallon container. You can adjust the quantity based on whether the container is larger or smaller.
You need to add such fertilizer just once or twice during the growing season of the plants. You should just add it to the top of the soil and mix it in the top 1-2 inches. This helps prevent disturbing the roots and the organisms in the soil.
The granules are coated with a resin that releases the nutrients on getting moist. The problem is that these covers remain in the soil and make it difficult to know whether you need to apply more fertilizer.
How to apply the natural liquid fertilizer
The other type of natural fertilizer you use is liquid fertilizer. You dilute this with water as per the recommendations and spray it on the soil and the foliage.
This is a fast-acting fertilizer that instantly provides nutrients to the soil and the plant. You need to use this fertilizer every two weeks as a thumb rule.
But when plants like tomatoes start growing fruit, you need to use it every week for good plant and fruit growth.
You could even dilute the liquid fertilizer with more water and use it every alternate day as part of your watering schedule.
Find out how much of the liquid fertilizer you need to dilute with water. This instruction should be available by the manufacturer.
If the information is not available, as a thumb rule, you can dilute 2 tablespoons of liquid fertilizer per gallon of water.
To apply the liquid fertilizer, you again need to check the manufacturer’s instructions. If there are none available, the thumb rule is to spray 1 ounce of diluted liquid fertilizer per gallon of the container soil.
So if you have a 5-gallon container you need to spray 5 ounces when fertilizing the container soil.
If the containers are small, you can just give them a splash of the liquid fertilizer.
You can find out more about the basics of container gardening including using organic fertilizer and what type you can use.
Here are some of my favorite container gardening tools
Thank you for reading this post. I hope it helps you with your gardening needs. I’ve listed some tools below that can help you with container gardening. These are affiliate links so I’ll earn a commission if you use them.
Gardening Gloves – I find the Pine Tree Tools Bamboo Gardening Gloves really good for both men and women. It’s made from bamboo so helps absorb perspiration. They are also comfortable and fit very well.
Containers – You know picking the right container is crucial for your container gardening. I’ve written a detailed post on the best containers you can choose from. If you’re happy with a plastic container, you can check out the Bloem Saturn Planter.
Watering Can – This is a must-have tool when you’re growing plants in pots or grow bags. It helps to water the potting soil without splashing on the foliage. The Kensington Watering Can is stylish, strong, and can provide precision when watering potted plants.
Trowel – Garden Guru Trowel is my favorite because it’s durable and comfortable to use. My gardening friends really love having a trowel because they use it for digging soil, mixing fertilizer, moving seeds, leveling out the soil, mixing compost or mulch, and also dividing tubers
Bypass Pruner – I really like the Corona Bypass Pruner because it’s durable and gives a clean cut that helps plants recover faster. If you’re looking for something cheap, get the Fiskars Bypass Pruner that is really good as well.
To see an extensive list of the best container gardening tools gardeners recommend, check out this resource that I made for you.
Kevin is the founder of Gardening Mentor, a website that aims to teach people to grow their own food in a limited space. As a self-taught gardener, Kevin has spent several years growing plants and creating gardening content on the website. He is certified in Home Horticulture and Organic Gardening by expert gardeners from Oregon State University.