Module 13: Adding Nutrients To The Potting Soil

Vegetable plants need a lot of nutrients to develop foliage, roots, flowers, and fruits. You’ll need to feed the potting soil regularly.

Nutrients Vegetable Plants Need

The important nutrients you need to provide are NPK (Nitrogen, Phosphorus, and Potassium). Nitrogen helps in the foliage growth of the plant. Phosphorus helps in root development. Potassium helps in overall growth and health of the plant.

When the vegetable and herb plants are growing, you need to provide these nutrients depending on the plant and growth stage.

What Can You Feed Plants?

You can provide nutrients to the plants using compost and/or fertilizer that you add to the potting soil. 

Compost: is organic matter formed by decomposing organic materials such as grass clippings, straw, dried leaves, vegetable waste, wood chips, etc.

Fertilizer: is material that contains nutrients in varying ratios. It can be organic or synthetic. I recommend using only organic fertilizer because it’s safer for the plant and the environment. You can get fertilizer in solid or liquid form. 

Solid fertilizer: These are in granules or pellets form. You add the solid organic fertilizer to the potting soil and it slowly releases nutrients into the soil.

Liquid fertilizer: is available to dilute with water and spray on the plant. You can add the liquid organic fertilizer into the potting soil or you can directly spray it on the foliage. Liquid fertilizer takes effect faster than solid fertilizer as the nutrients are immediately available.

What Fertilizer Should You Use?

Foliage growth: When the vegetable is growing foliage, you want to use a nitrogen-rich fertilizer. This will encourage growth of the stem, leaves, and branches of the plant. This is especially useful to grow leafy vegetables where you want more foliage.

Some nitrogen-rich fertilizers are seaweed extract, Fish emulsion, Blood meal, Neem cake powder, Cow manure, Chicken manure.

Burpee Organic Blood Meal Fertilizer

Root growth: If you’re growing root vegetables or just want good overall development of a plant, you can choose a balanced fertilizer. It will have the right amounts of Nitrogen, Phosphorus, and Potassium.

Down to Earth Organic Vegetable Garden Fertilizer

Flower and fruit growth: If you’re growing fruiting vegetables such as tomatoes, there will be a time when it starts to flower and fruit. You’ll need to stop using nitrogen-rich fertilizer as you don’t just want foliage. And you’ll need to start using potassium-rich fertilizer.

An example of potassium-rich organic fertilizer is potash.

Easy Peasy All- Natural Muriate of Potash

I’ve created a list of different vegetables and you can find their fertilizer requirements there.

Container Plant Information List

When To Feed Nutrients?

You can start feeding compost and fertilizer after you have transplanted the seedling into the container outdoors. You don’t need to feed nutrients while the seed germinates and is developing its true leaves. The seed already contains sufficient nutrients for the plant.

After the transplant, you can start adding compost and/or fertilizer once every 15-20 days to the potting soil.

During the foliage growth stage, you can add the nitrogen-rich fertilizer. During the flower and fruiting stage, you can add potassium-rich fertilizer.

How To Add Nutrients To Soil

The amount of fertilizer you need to use depends on the instructions provided with the fertilizer packet. Don’t use more than the suggested quantity. If there is no instruction on the packet, then you can use a 1-inch layer of the fertilizer.

You can do the same if you’re using compost. Place a 1-inch layer of the compost on the potting soil.

Once you’ve placed the layer of compost or organic fertilizer, mix it into the potting soil. Use a trowel to mix it 1-2 inches deep.

After adding the compost or fertilizer, give the potting soil deep watering. Use the watering can to water the soil until it drains out from the drainage holes.

Repeat this process of adding nutrients once every 15-20 days as the plant is growing.

Precautions When Adding Nutrients

• Avoid using nutrients when starting seeds. You only need to add fertilizer once the seedlings are transplanted and a few days have passed.
• Use fertilizer in the right dosage as mentioned on the package. Avoid over-fertilizing the potting soil even with organic fertilizer. You risk damaging the plant roots.
• Use the right fertilizer during the appropriate plant growth stage. Avoid using nitrogen-rich fertilizer when the plant is flowering and developing fruits. It will stunt their growth.
• My recommendation is to use organic fertilizer. Avoid using synthetic fertilizer that can harm the plant and the ecosystem.

Action Steps

• Buy the compost and necessary fertilizer for the vegetables and herbs you want to grow.
• Apply the compost and/or fertilizer every 15-20 days after transplant.
• Follow instructions on the fertilizer package on the dosage you should use.
• Mix the compost and/or fertilizer 1-2 inches into the potting soil.
• Give the potting soil a deep watering after adding the compost and/or fertilizer.