Ultimate Guide to Micronutrients

Plants need water, good soil, and clean air, but they also need trace elements to boost their nutrient content and promote living processes. What are micronutrients, and how can I work with them, you ask? Read on and find out!

Essential Plant Nutrients

Essential nutrients for growth include a combination of macro and micro-nutrients.

Macronutrients exist in the air plants breathe and the water they consume. These 3 elements (Carbon, Hydrogen, and Oxygen) are the foundational building blocks of plant growth.

Plants derive hydrogen (H) and Oxygen (O) from the air and water. Carbon (C) also comes from the perspective and the broken down matter that becomes soil.

Ultimate Guide to Micronutrients

Without these essential nutrients, plants cannot live out their life cycle. So providing plants with good clean air, water, and soil is foundational to good growth. But there is more they need.

What are Mineral Nutrients?

Plants want to thrive, and growers can provide an avenue for healthy growth with mineral nutrients. Mineral nutrients are those plant nutrients found solely in soil. Plants can live without them, but they may not live out their entire life cycle.

When we garden, we want to mimic plants’ natural habitat to give them the best possible growing conditions.

Certain mineral nutrients are naturally present in the soil. A soil test can help growers gain insight into how to enhance the presence of 1 mineral nutrient while ensuring that concentrations of some do not exceed amounts acceptable for plants.

Air, water, and mineral nutrients in soil combine to fortify plants with a strong foundation. Without 1 of these essential nutrients in the correct amount, growers will see stunted plants with discolored leaves and a lack of fruit and vegetable production.

To ensure a plant can live most securely and efficiently, growers apply fertilizers to change the plant’s nutrient content via soil drench or foliar application.

Even those who dip their toes in the plant care pool know of the 3 most common mineral nutrients available in fertilizer form: Nitrogen (N), Phosphorus (P), Potassium (K).

Different plants prefer different formulations of these nutrients, and commercial fertilizers will balance formulations for specific plants.

Ultimate Guide to Micronutrients

For instance, certain rose NPK fertilizers will use different elements to make a ratio of 4-8-4, which provides more Phosphorus for flowering than Nitrogen for root affixation or Phosphorus to move water through the plant ease.

Growers can also enhance soils with powdered forms of Sulphur (S), Calcium (Ca), Magnesium (Mg). Or, compostable solutions can be buried in garden beds. More on this in a bit!

What Are Micronutrients?

However, there are those nutrients that are not essential for plant life, but they support healthy plant growth. They have the power to change the way you garden, despite the fact they are only needed in tiny amounts (less than 1mg).

These are Manganese (Mn), Copper (Cu), Zinc (Zn), Molybdenum (Mo), Boron (B), Chlorine (Cl), and sometimes Iron (Fe). These micronutrients have specific functions in your growing space. They are as follows:

Building strong cell membranes: Boron and Zinc protect plant cells by fortifying cell walls and keeping free radicals that can weaken them.

  • Catalyzing enzyme activity: Iron, Manganese, Copper, Zinc, and Molybdenum work together to create and bolster proteins plants need to metabolize other nutrients.
  • Carrying electrons: Manganese bonds to essential nutrients to promote electron transport through mitochondria and the photosynthesis process. Electric!
  • Maintaining osmotic pressure: Chlorine regulates plant relationships to water and salt content, balancing and filtering out salt when needed.
  • Promoting healthy biosynthesis: compounds of several micronutrients assist plants in nutrient and water absorption.
  • Protecting plants from oxidative stressors: combinations of micronutrients in conjunction with essential nutrients protect plants from free radicals and pathogens.
  • Regulating nutrient uptake: Boron and Zinc assist plants in nutrient uptake either positively by promoting absorption of a nutrient or negatively by preventing or balancing cell death.
  • Ensuring healthy reproduction: multiple micronutrients help reproductive organs grow and proliferate on plants.

In this video, Brian discusses what are minerals, what do minerals do in the body, as well as minerals nutrition:

Gardening with Micronutrients

All this scientific jargon can be overwhelming, so how should one use micronutrients and observe their benefit in practice?

There are multiple ways to apply and understand micronutrients in the garden. It is easier to add micronutrients before planting.

Ultimate Guide to Micronutrients

But if you’re already growing, no problem. This guide will break down how to deal with micronutrient boosts on either side of the planting stage.

Pre-Planting Phase

Soil Tests

The first thing you want to do when determining how to amend the soil with the proper amounts of micronutrient content is based on an adage: Don’t guess! Test!

Find a local university or agricultural extension that can provide you with a free soil test. Generally, these give you several bags to sample multiple areas of your garden, which you can send into the extension lab where the soil is tested.

The lab will provide you with a full workup of the nutrient content of the soil. These tests can take up to 8 weeks sometimes. Allow yourself the time to test before sowing seeds or transplanting.

There are other options for soil tests. You can buy a simple pH tester from a local garden store, Amazon, or other outlets.

This tester will give you a general understanding of your soil’s pH and determine at the very base whether the soil needs to be amended.

However, this general overview does not give as drilled down of an outlook as a complete soil test. There are full spectrum soil tests for purchase at the exact locations you can find a pH tester if there isn’t a local agricultural extension in your area.

Experts suggest a combination of soil tests (both pH and nutrient tests) and plant observation. This full-spectrum approach gives you the best indicators of which micronutrients need to be added to the soil.

Tissue Tests

Say you are working in a bed that has plants growing in it. You are ready to pull up the old growth and plant new growth. This is an excellent time for a plant tissue test.

Ultimate Guide to Micronutrients

The plants already in your bed are in a mature stage, and you can test the plant matter to determine the general nutrient makeup.

There are commercial tests out there, but one drawback is that many of them require large amounts of plant tissue to provide reliable results. They are also expensive.

Some commercial plant tissue tests start at $150. The most significant benefit here, however, is many of these commercial tissue tests give you a full workup of all plant macro-and micronutrients.

Some tests will even provide nutrient-balancing recommendations based on your plant samples. Therefore, tissue tests are great if you have a backyard farm but may not be as effective for backyard gardening.

Compost

The absolute best solution for all micronutrient deficiencies is building a healthy compost system to draw from each season.

Amending soil with plant matter you have grown with green scraps from your kitchen, combined with brown matter from your land or backyard, will best mimic the healthiest parts of your surrounding ecosystem in the correct balance.

This is truly what plants need. And if you plan, you can add different matter to your compost to boost specific plants’ nutrients.

For instance, eggshells can be washed, dried, processed, and added to compost, providing calcium for your next season’s tomato crop. However, calcium is a macronutrient.

So what about micronutrients? Think about the way you feed your body nutrients. Very similarly, the soil breaks down greens, adding iron to your compost.

Soil Enhancers

There are also commercial soil enhancers that increase the nutrient content of your soil. Whether you decide to use a nutrient meal or a mineral supplement, soil enhancers’ applications generally occur when you are prepping for planting.

Ultimate Guide to Micronutrients

Some of these amendments, however, can be added to the soil for immediate use. These release into the soil slowly, providing plants with the nutrients they need over an entire growing season.

Post-Planting Phase

But what if your plants are already in the garden bed? There are still ways to add micronutrients via fertilizers and soil applications at this stage.

Fertilizers

Fertilizers should be applied out of the sun’s direct heat, usually at dusk, and never during cold weather when plants are in a stressed state.

Develop a relaxing routine on Saturday nights in spring, summer, and early fall, where you head out to your garden at dusk for plant feeding time.

Soil Drench

Many fertilizers prescribe what is known as a soil drench or the application of diluted fertilizer at the plant base. Fertilizer of this kind is mixed in a solution of water and poured into the soil, allowing the plant roots to soak up micronutrients.

Often these are sold in small to large jugs and last gardeners a long time as dilutions are necessary.

Non-diluted soil drenches for those who require dilution could burn the plants and give them too much of a good thing. So read the instructions carefully.

Foliar Applications

You can also apply certain soil drench fertilizers in spray form on leaves and flowers. Again, dilution is key, and some kind of sprayer is required for application.

Ultimate Guide to Micronutrients

Purchase sprayers at your local hardware store. Those on the lower end start around $12. Higher performing sprayers start at about $25.

If you are covering a small area, a regular spray bottle works for this task. Just ensure you clear out blockages between applications to make the process smoother.

These applications work their magic because leaves absorb nutrients from the soak. This is especially effective when micronutrients in the applied solution have a cell protection function.

Foliar applications help strengthen plant cell walls and prevent certain pests from proliferating.

On-Soil Applications

What if you have some great soil amendments or compost, but you only just realized that your plants need a boost. What if they are just getting established for the growing season?

You can still add soil amendments at this point, though the process requires much more careful attention, and nutrient absorption will take a little more time than if you completed the process ahead of growing.

To apply a soil amendment at this stage, make a small trough on either side or around your plants. Depending on the planting style, you can create troughs in a straight line or in a circle around each plant for those plants that require more spacing between them.

Just add some compost or greensand, meal, etc., in the trough and cover with garden bed soil. Water in, and wait a week or so for results!

Cover Crops

Say it is the end of a growing season, and you know based on leaf discoloration, stunted growth, a soil or tissue test, or a lack of production that your bed needs something.

Cover crops are the slowest method of adding nutrients to your soil, so planning is essential here. Cover crops work to restore nutrient content to the soil in varying ways gradually.

Ultimate Guide to Micronutrients

Grow cover crops to be chopped down with a scythe or clippers. Dead plant matter left on top of the bed feeds nutrients into the soil, much like hay or leaves in compost.

Different crops are planted at different seasons and are usually grains, grasses, or legumes. Check a list of cover crops and their benefits to determine the best crop for your purposes.

For instance, clover will help your bed affix nitrogen for future plants. And that’s not the only cover crop that affixes nitrogen. All of them do!

But some are more suited to specific nutrient deficiencies or balances than others. Do some research before deciding which crop to cover.

Let’s learn what important minerals you need and the foods that contain them:

Summing it Up

Understanding micronutrients in your garden is one of the best skills in your gardener tool belt. Deficiencies and imbalances cause stunted plant growth and slow the healthy processes of a plant’s life cycle.

No need to fear, though! Micronutrients re-balance soil health through several different methods in either pre-planting stages or after planting is complete.

By understanding the trace elements each plant needs, gardeners can master understanding micronutrients.

Author: Sarah Jay from sarahjaywriting.com

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Jill Sandy

Jill Sandy

Jill is a sustainable focus gardener. She loves decorating her home backyard with beautiful landscape design and creative garden care techniques she develops herself. You can reach her at jill.sandy@constantdelights.com

Chanh Ho (MD, MPH)

Chanh Ho (MD, MPH)

Chanh is our Head of Medical Review. He is a research physician at Oxford University Clinical Research Unit. After accomplishing the program of level 1 sub-specialty in Pediatrics, he was awarded the Chevening Scholarship for his Master’s degree of Public Health in the University of Edinburgh in 2019

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