What Fertilizer Ratio Should You Use When?

What Fertilizer Ratio Should You Use When?
What Fertilizer Ratio Should You Use When?

What Fertilizer Ratio Should You Use When?

As a soil scientist I am passionate about the idea of delivering specific nutrients at certain times. Knowing what fertilizer ratio you should use when in the garden is important for ensuring maximum fruit and vegetable harvests. This is even more true when it comes to people living in cold climates or gardening in Canada.

Choosing a fertilizer based on the plants stage of growth is a great way to save money & have better results. Certain nutrients are known to stimulate different types of growth. Tailoring your fertilizer based on the plant’s health is also a great way to help a plant through a bug attack. You can even use specific nutrient ratios to ensure better results when transplanting or trimming.

How To Read Fertilizer Labels

We have all seen the three letters N-P-K, which are usually translated into a number. For example 5-7-4, which is the percentage of the product that has each value. This means the higher the values the less filler there is in the product. An example of a product with a higher percentage of nutrient value is miracle gro all purpose. This product rings in at 24-8-16, this means in every 10 lbs of products we will find, 2.4 lbs of Nitrogen, 0.8 lbs of Phosphorus and 1.6 lbs of Potassium. The remainder of the product being filler to help aid in solvency, slow release, and stabilization in solution.

What Does Nitrogen Fertilizer Do

Nitrogen (N) is the fuel to vegetative growth above ground. Nitrogen is the key ingredient behind chlorophyll which we all know is essential to photosynthesis. Nitrogen in exces can result in rapid growth and thin leaves. These thin leaves can encourage pests and disease to take route. That means more is not always a good thing. 

Nitrogen is applied as a fertilizer regularly throughout the growing season because nitrogen is easily lost from the soil. The main mechanisms that nitrogen leaves the soil is via leaching and volatilization. These are both fancy words for saying through gravity and into the air respectively.

What Does Phosphorus Fertilizer Do

Phosphorus (P) is essential for roots and flowers. Do to this it is important to increase the level of phosphorus when expecting flower development. This is not as important in the seed starting stages. 

What Does Potassium Fertilizer Do

Potassium (K) activates enzymes. These enzymes help the plant handle stress such as transplant shock, changes in temperature and soil moisture. This is the ideal supplement to give after transplanting outdoors.

What Does Calcium Fertilizer Do

Calcium (Ca) is important in transporting information around the plants. A great example of this is the Tel Aviv plant study where they measured increases in calcium to an injured area of the plant. Beyond that it is important to the plant’s cell structure.

What Does Magnesium Fertilizer Do

Magnesium (Mg) is used in enzyme reactions within the plant which are essential to chlorophyll. Without Magnesium photosynthesis can not occur.

What Does Sulphur Fertilizer Do

Sulfur (S) is the foundation to the plant’s immune system.

What Fertilizer Ratio Do You Use During the Seedling Stage?

When the plant is a seedling the main focus is on roots and shoots. Therefore you want to go with a fertilizer with higher nitrogen and phosphorus. Click here to check out my entire blog post on fertilizing seedlings.

This is a list of the fertilizers to use for seedlings:

Organic Fertilizer Options For Seedlings

BudJuice – Nitro

Gaia Green Blood Meal

Inorganic Fertilizer Options For Seedlings

Miracle Gro All Purpose

What Fertilizer Ratio Do You Use After Transplanting?

If we have hardened off our plants properly then our main focus will be roots and treating stress. This means our main nutrients will be phosphorus, potassium and if possible sulphur.

This is a list of fertilizers to use after transplanting:

Organic Fertilizer Options For Seedlings

BudJuice 0-0-15

Inorganic Fertilizer Options For Seedlings

Promix Fertilizer

What Fertilizer Ratio Do You Use For Flowering Plants?

If you are trying to encourage a plant to flowers or already have flowers emerging then you will want to supply the plant with higher levels of phosphorus. If you are having an issue with flowering it mostly likely is due to over applying nitrogen to the soil.

This is a list of fertilizers to use with flowering plants:

Organic Fertilizer Options For Seedlings

BudJuice 2-14-0

Gaia Rock Phosphate

Inorganic Fertilizer Options For Seedlings

Miracle Gro Bloom Formula

What Fertilizer Ratio Do You Use For Stressed Plants?

A stressed plant is any plant that has gone through a heat wave, a cold snap, transplanting, or from pest/disease pressure. This means higher levels of potassium and sulphur when possible.

This is a list of fertilizers to use on stressed plants:

Should you be using liquid or dry fertilizers? 

The quick answer to this is liquid, however dry has its time and place. For more info on the differences between the two check out my blog post here.

There you have it an in depth guide from a soil scientist going over exactly what fertilizer to use when. You are now prepared to give your plant the nutrient it needs when it needs it. Let me know in the comments below which fertilizers you enjoy and why. For more info on garden science check me out on YouTube.

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