Understanding NPK Fertilizers.

At this time of year, some of the plants in your garden are really starting to grow, while others are still in the early stages of growth and are turning strange colors like yellow or purple. You might ask, "What does it all mean?!?" Well, on the Garden Club blog, we want to help you figure out these nutrient mysteries so you can grow plants that are big, tasty, and healthy.

The classic triad of NPK, which stands for nitrogen, phosphorus, and potassium, is well known to most gardeners. We're going to explain these to you today. I strongly suggest that every gardener (especially those who plant directly in the ground or have large gardens) get their soil tested every spring. buy npk fertilizer At your local garden centre, you can buy a cheap test that will give you a general idea of what's going on in your soil. A & L labs is a great place to do this on a larger scale and for a higher price. They accept soil samples sent in by mail and give great explanations along with the results.

When you get the results of your soil test, you'll know where your soil is strong and where it needs improvement. With that information, you can make a plan to add the needed nutrients to the soil in solid (think boxes of granulated fertilizer or 50-pound bags of powdered gypsum) or liquid (spray-on) form.

How do you know which ratio of NPK fertilizers to use?

It's important to remember that the three numbers on bags and boxes of fertilizer show the percentage (by weight) of the three main nutrients plants need to grow well. Nitrogen, phosphorus, and potassium are always in that order (NPK). When in doubt, add a "balanced" Fertilizer to your garden, such as 5-5-5. This means that the three numbers are close to each other.

If you know that your soil doesn't have enough of a certain nutrient, look for the number for that nutrient to be much higher than the other two. Before you plant, you might want to work fertilize deep into the soil to help the roots grow strong. A ratio of about 3-20-20 would work well for this.

Also, a plant needs a lot of nitrogen early in its life to grow big, so look for the first number that says "nitrogen" to be higher (16-6-4 is a common ratio for a nitrogen-rich fertilizer).

When your plants are ready to flower, you can switch back to the 3-20-20 fertilizer to help them grow during this stage.

All of these types of fertilizer are available in organic versions. Organic fertilizers are strong, effective, and don't have any harsh chemicals. They are often made with things like blood meal, bone meal, rock phosphate, kelp, and oyster shell flour. Ask about organic options at your local garden store.

Let's look at these three macro nutrients and what they do for your plants in a little more detail.

Understanding NPK Fertilizers: Nitrogen

Nitrogen is at the front of the "NPK" line because it is so important to a plant's growth and development. Nitrogen is a part of every protein in plants, and it is used in almost every process that plants do during their life cycle. The process of making big leafy canopies and tall green stems is most dependent on nitrogen. We all remember from middle school science that chlorophyll is what gives plants their green colour and helps them do photosynthesis. Well, nitrogen is also an important part of chlorophyll.

As nerdy gardeners, we know that something is "nitrogenous" if it is green, leafy, soft, and moist. (This is often compared to "carbonaceous" materials, which are brown and dry and take longer to break down when building compost piles.

In the early stages of a plant's growth, nitrogen is often very important, and it's good for the plant to grow a big frame before it sets fruit. At that point, nitrogen, or too much of it, can actually stop the plant from growing the part you want to eat. Last year, I was very proud of the Padron peppers I grew in a low tunnel greenhouse. They started to grow big, tall plants, which I helped along with a few doses of blood meal, which is high in nitrogen. Well, to my surprise, by September I had pepper plants that were shoulder-high and a beautiful deep green, but they didn't have many peppers on them. I used too much nitrogen, which slowed down or stopped the plant from moving from its vegetative (green growth) stage to its reproductive (flowering) stage (when it grows fruit that will eventually produce seed). Oops.

When plants need it: From planting until they flower, but especially in the beginning of their lives. Compost and cover crops are great sources of nitrogen that is released slowly, which is always good for a plant. But the kind of nitrogen in fertilizers that works quickly should only be used until a plant is ready to flower.

How to tell if you don't have enough: A yellow colour where there should be green, few fruits, or small, stunted plants. Too much nitrogen, or too much nitrogen at the wrong time in a plant's life cycle, can make the plant grow big, but it may take longer for it to flower.

How to add it: Compost, organic matter, fish and kelp solutions, compost tea, and manure are all good sources of nitrogen.

Understanding NPK Fertilizers: Phosphorus

Phosphorus is also an important part of photosynthesis and helps a plant make its sugars, starches, and oils. It makes sweet fruits taste sweeter and is a key part of how plants make seeds and make protein. It also helps a plant's immune system. A plant with a lot of phosphorus is better able to handle stresses from the environment than a plant with little phosphorus. Nitrogen helps a plant grow big, healthy leaves, while phosphorus helps it grow strong roots and then helps it bloom once the flowers have formed.

When plants need it: It's best to put it in when you plant the seeds or a few days before.

How to tell if you don't have enough: If a fruit looks healthy but isn't sweet, it could be because it doesn't have enough phosphorus. Phosphorus deficiency can also show up as short plants, few fruits and flowers, and flowers that look strange and weak. Too much phosphorus makes it hard for a plant to take in zinc and other nutrients. This means that if your soil test said you should add more phosphorus, you should also make sure to balance out other nutrients that are related.

Understanding NPK Fertilizers: Potassium

Potassium is important for plants because it helps them store, use, and control their energy. Potassium also helps control the amount of water pressure inside plant cells. Throughout its life, a plant needs to learn how to store and use energy and water to help it deal with stress (derived from heat or cold, poor soil conditions, improper handling by impatient gardeners, or munching from critters). Potassium helps plants respond to and get over this stress in all of the ways it works. Potassium is a very important part of my cut flower farm. Stems that are long and stiff need a lot of potassium.

When plants need it: All the time, but it's best to add it before you plant them.

How to tell if you don't have enough: Potassium deficiencies can be seen in low yields and leaves that are curled, spotted, weak, or burned. If a plant has too much potassium, on the other hand, it may look big and beautiful, but its structure will be very weak.

Calcium and magnesium are also very important.

I would be wrong not to give a shout-out to calcium and magnesium, who are also very important. Calcium is another nutrient that helps plants get stronger. It is also important because it helps plants absorb and use all of these other nutrients. Even if the macro nutrients are all right, plants that grow in soil that is high in one nutrient but low in calcium may have clear deficiencies. It also makes the soil easier to work with. Heavy clay soils often need more calcium, and gypsum is often the best way to get it.

Another important micro nutrient is magnesium, which helps plants use a lot of other nutrients. To make carbohydrates and sugars, enzymes in plants need magnesium. Also, seeds, flowers, and fruits need the right amount of magnesium to be healthy.

It takes a lifetime to learn about soil nutrients, but we hope this overview will help you try to fine-tune your soil. Do you still have questions about how to use NPK fertilizers? Ask them in the section below, and we'll do our best to help!