If you thought people were the only ones who needed iron, then consider this an eye-opener! Since there are so many vegetables high in iron, it’s only logical that they also found this nutrient in the soil.
But why do we need to have iron in the soil? How does it impact our plants?
Today, we’ll be checking out why iron is important, and which fertilizers we can use to pump up the iron levels in the soil!
Let’s get started.
Why is iron important for plants?
Iron is often called the “greening nutrient” because it helps plants thrive and flourish. Let’s start with how iron affects plants in the process of photosynthesis.
Photosynthesis helps plants turn sunlight, water, and carbon dioxide into energy. Chlorophyll, a green pigment in plant cells, is at the core of this process.
Iron is essential for chlorophyll, and without it, photosynthesis can’t work properly. When plants lack iron, their leaves turn pale yellow due to a lack of chlorophyll.
Iron Deficiency Signs and Symptoms
Too often we can ignore how iron, no matter how minute, affects our plants. Here are some things you need to look out for to check if your plants need more iron in their diets.
Yellowing Leaves (Chlorosis)
This is where their youngest leaves turn yellow due to impaired chlorophyll production.
Interveinal Chlorosis
Veins remain green while the areas between them turn yellow.
Stunted Growth
Iron-deficient plants don’t grow as well.
Leaf Drop
Severe cases lead to premature leaf shedding.
Poor Flower and Fruit Development
Iron deficiency affects the quantity and quality of flowers and fruits.
Types of Fertilizers with High Iron Content
Now that we know what to watch out for in case of iron deficiency in plants, it’s time to check for fertilizers that are high in iron.
Iron Chelates
| Factor | Description |
| Expertise Level | Moderate ●●○○○ |
| Suitable for | Plants in alkaline soils with iron deficiencies |
| Benefits | Corrects iron deficiencies, enhances plant growth |
| Possible Risks | Overuse will lead to iron toxicity, should be used as directed on the product label |
Iron chelates are organic compounds that contain iron in a form readily available for plant uptake. Chelates protect the iron from binding with other elements in the soil, ensuring it remains accessible to the plant’s roots.
How to Use Iron Chelates
1. Apply at the right time.
Apply iron chelates during the growing season, ideally in the morning or evening when it’s not too hot. Avoid applying in the middle of the day.
2. Follow the instructions on the label.
Always read and follow the instructions on the product label. This includes dosage, frequency, and safety info.
3. Pick your preferred application method.
Foliar Spray: If you need a quick fix, mix the recommended amount of iron chelate with water and spray it evenly on the plant’s leaves. Make sure to cover them well but avoid excess runoff.
Soil Drench: For a longer-lasting effect, mix the iron chelate with water as directed and pour it into the plant’s root area. This lets the roots absorb the iron.
4. Don’t overdo it.
Be careful not to use too much iron chelate, as too much iron can harm plants. Stick to the recommended amount and schedule.
5. Keep an eye on the progress.
Watch your plants after applying. It might take a bit for the iron chelates to work. If needed, reapply as suggested by the manufacturer.
6. Store properly after use.
Store iron chelate products in a cool, dry place, away from sunlight, and out of kids’ and pets’ reach.
Iron Sulfate
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | Acid-loving plants (e.g., azaleas, rhododendrons, blueberries), soil pH adjustment |
| Benefits | Provides iron in a form easily absorbed by plants, corrects iron deficiencies, will lower soil pH when needed |
| Possible Risks | Overuse will lead to iron toxicity, may lower soil pH excessively and affect other plants if not used carefully |
Iron sulfate, also known as ferrous sulfate, is a water-soluble iron fertilizer. It provides iron in the sulfate form, which is readily taken up by plant roots.
How to Use Iron Sulfate
1. Choose the right plants.
Iron sulfate works best for plants that love acidic soil, like azaleas, rhododendrons, and blueberries. Double-check that your plants fit into this group.
2. Apply at the right time.
Use iron sulfate during hours when your plants are growing and taking in nutrients. Usually, this happens in the morning or evening.
Avoid applying iron sulfate in extreme heat or when your plants are stressed.
3. Pick your preferred method to apply.
For the Soil: To get long-term results, sprinkle iron sulfate granules evenly around the base of your plant on the soil surface. Refer to the instructions on the product label for how much to use.
For the Leaves: Mix iron sulfate with water as the label suggests and spray it on your plant’s leaves. Make sure you cover the leaves evenly but avoid any spray runoff.
4. Follow the instructions on the product label.
The product label will tell you how much to use, how often, and any safety advice. Follow the instructions so you can avoid damaging your plants.
Using too much will harm your plants. It will also make your soil too acidic.
If you’re using iron sulfate to lower your soil’s pH, keep an eye on it with a soil test kit. Add more if needed, but don’t make it too acidic.
5. Watch your plants for reactions.
After using iron sulfate, be patient. It might take a while to see the results. If necessary, use it again as the label suggests.
Store iron sulfate in a cool, dry place, away from sunlight, and where kids and pets can’t reach it.
Iron EDTA
| Factor | Description |
| Expertise Level | Moderate ●●○○○ |
| Suitable for | A wide range of plants |
| Benefits | Provides a long-lasting source of iron, versatile and suitable for various plants |
| Possible Risks | Overuse will lead to iron toxicity, follow label instructions for proper application |
Iron EDTA (ethylenediaminetetraacetic acid) is another chelated iron fertilizer. It is particularly stable and provides a long-lasting source of iron for plants.
How to Use Iron EDTA
1. Check plant needs.
Before using Iron EDTA, look for signs of iron deficiency. These include yellow leaves with green veins on your plants.
Pick an Iron EDTA product suitable for your plants.
2. Pick the right application time.
Apply Iron EDTA during the growing season, preferably in the morning or evening when it’s not too hot.
3. Follow label instructions.
Always read and follow the instructions on the product label for dosage, frequency, and safety precautions.
4. Determine the right application method.
Foliar Spray: Mix Iron EDTA with water and spray it evenly on the plant’s leaves for quick absorption. Make sure to cover the leaves but avoid excessive runoff.
Soil Application: For long-term effects, mix Iron EDTA with water as instructed on the product label and apply it to the plant’s root zone for root absorption.
Whicher application method you choose, don’t exceed the recommended dosage and application frequency to prevent iron toxicity. Stick to the guidelines on the label.
5. Check your plant regularly.
Be patient and check your plants after applying Iron EDTA as it might take some time to see results. If needed, reapply following the manufacturer’s recommendations.
Keep Iron EDTA products in a cool, dry place, away from direct sunlight, and out of the reach of children and pets.
Iron DTPA
| Factor | Description |
| Expertise Level | Moderate ●●○○○ |
| Suitable for | Plants in slightly alkaline soils where other chelated iron fertilizers may lose effectiveness |
| Benefits | Effective in a broader pH range, corrects iron deficiencies |
| Possible Risks | Overuse will lead to iron toxicity, should be used as directed on the product label |
Iron DTPA (diethylenetriaminepentaacetic acid) is a chelated iron fertilizer that remains effective in a broader pH range than some other chelates.
How to Use Iron DTPA
1. Check if your plants do have iron deficiency.
Look for signs like yellow leaves with green veins.
2. Pick the proper product.
Select an Iron DTPA product suitable for your specific plants. Follow the manufacturer’s instructions for recommended application rates and timing.
3. Time the application properly.
Apply Iron DTPA during the growing season, preferably in the morning or evening when temperatures are mild. Avoid applying it during the hottest part of the day.
4. Follow product application instructions.
Always read and follow the instructions on the product label. This includes details about dosage, frequency, and safety precautions.
Don’t overapply Iron DTPA, as too much iron will harm your plants. Stick to the recommended dosage and application schedule.
5. Determine the appropriate application method.
Foliar Spray: For quick results, use a foliar spray. Mix the recommended amount of Iron DTPA with water and evenly spray it on the plant’s leaves.
Make sure that there’s good coverage without excessive runoff.
Soil Drench: For longer-lasting effects, go for a soil drench. Mix Iron DTPA with water as directed and pour it directly into the plant’s root zone, allowing the roots to absorb the iron.
6. Monitor your plant’s health.
Keep a close watch on your plants after applying Iron DTPA. Remember that it might take some time for the iron to address the deficiency.
If needed, reapply following the manufacturer’s recommendations. Store Iron DTPA products in a cool, dry place, away from direct sunlight, and out of reach of children and pets.
Iron Fertilizer Spikes
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | Trees, shrubs, and larger plants with established root systems |
| Benefits | Convenient slow-release iron source, ideal for larger plants |
| Possible Risks | Risk of over-application if not used as directed |
Iron fertilizer spikes are convenient, slow-release options for providing iron to plants. They consist of compact spikes that are driven into the soil.
How to Use Iron Fertilizer Spikes
1. Choose the right product.
Select iron fertilizer spikes that match your plant’s type and size. Good-quality fertilizer spikes will indicate the right plant type for the spikes.
2. Prepare the soil.
Make sure the soil around your plant is moist but not overly wet. Don’t use the fertilizer spikes in very dry or very wet soil.
3. Insert the spikes.
Place the iron fertilizer spikes in the soil around the plant’s roots as indicated on the product label. The placement may vary depending on the plant’s size and spike design.
Use the recommended number of spikes. Too many will harm the plant by over-applying iron.
4. Space the spikes properly.
Space the spikes evenly around the plant’s drip line to help the iron distribute evenly. Insert the spikes at the recommended depth.
Most of the time, it’s usually just a few inches into the soil. Avoid placing them too close to the plant’s base to prevent root burn or damage.
5. Cover the holes.
Go over the holes with some soil to cover them and secure the spikes in place.
6. Water the soil lightly.
Give the area around the spikes a light watering. This will activate the slow-release process of the fertilizer spikes.
7. Watch your plants.
Monitor your plant’s health over time. It may take a few weeks for you to see any progress or improvements.
Keep any remaining spikes in their original packaging in a cool, dry spot away from sunlight and away from children and pets.
Greensand
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | Gardens emphasizing organic and sustainable practices |
| Benefits | Enhances soil structure, provides slow-release iron, contains potassium and magnesium |
| Possible Risks | Excessive use may alter soil pH, slow-release nature may require patience |
Greensand is a naturally occurring mineral known for its high iron content. It’s a slow-release source of iron and also contains other essential minerals such as potassium and magnesium.
How to Use Greensand
1. Assess your soil.
Before using greensand, assess your soil. You can use soil testing kits to find out if it lacks iron or other essential minerals.
2. Time the application well.
Greensand can be used any time during the growing season. Having said that, we recommend applying it in the spring before planting or as part of your annual garden maintenance routine.
3. Choose the right greensand.
Get high-quality greensand from a reputable supplier, either locally or online. Make sure that your supplier provides you with the right greensand material to balance out your garden’s deficiencies.
4. Determine the application rate.
Follow the application rate on the product label. The rate will vary based on your soil’s condition and the plants you’re growing, so make sure to double-check your soil needs.
5. Incorporate greensand into your soil.
For garden bed preparations, mix the greensand well into the soil and make sure it’s distributed well. When adding new plants, put greensand in the planting hole and blend it with the soil to be used as backfill.
For existing plants, apply greensand as a top dressing around the plant’s base. Make sure to spread it evenly and all over the soil surface.
After applying greensand, water the area well to help it settle into the soil.
While greensand is generally safe, using too much can affect the soil pH. Stick to the recommended application rate to avoid any negative effects.
Keep any unused greensand in a cool, dry place, sealed tightly to prevent moisture exposure.
6. Monitor your plant.
Just remember that greensand slowly releases nutrients, so be patient and keep an eye on your plants and soil. It might take several weeks or even months to see the full benefits.
Blood Meal
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | Leafy green vegetables and iron-hungry plants |
| Benefits | Rich source of organic nitrogen, slow-release nutrient enrichment, high iron content |
| Possible Risks | Overapplication will harm plants, strong odor during application |
Blood meal is a rich source of organic nitrogen and iron derived from dried animal blood. It releases nutrients slowly, making it suitable for long-term soil enrichment.
How to Use Blood Meal
1. Identify the right plants for application.
Blood meal works best for leafy greens and plants needing extra iron and nitrogen. Make sure your chosen plants fit this category.
2. Time the application properly.
Apply blood meal during the growing season, usually in spring or early summer. Avoid use in extreme heat or drought conditions.
3. Determine the right amount.
Check the product label for recommended usage. Blood meal is potent, so avoid overuse to prevent plant damage.
4. Pick your preferred application method.
Sprinkling: For mature plants, evenly spread blood meal around the base, avoiding direct contact with stems. Don’t pile it up to prevent overuse.
Incorporation: When planting new seedlings or transplants, mix blood meal into the soil as advised. This provides a gradual nutrient release.
Watering: After applying blood meal, water the area well to activate the nutrients and protect plant roots from burning.
Store blood meal in a cool, dry place, tightly sealed to prevent moisture. Ensure it’s not accessible to kids or pets.
Blood meal has a strong smell and it’s not for people who are sensitive to odors. Remember this when choosing the application time, as some may find it unpleasant.
5. Monitor plant growth.
Keep an eye on your plant’s health. If you spot signs of over-fertilization like burnt leaves or stunted growth, reduce blood meal in future applications.
Compost
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | All types of plants; improves soil structure and nutrient availability |
| Benefits | Enhances soil fertility, improves soil structure, provides trace amounts of iron and other nutrients |
| Possible Risks | None when used appropriately and in moderation |
Compost is a well-rounded soil conditioner that contains trace amounts of iron among other nutrients. While it may not be as concentrated as other iron sources, it contributes to overall soil health.
How to Use Compost
1. Get good compost.
Find or make high-quality compost. Good compost is dark, crumbly, and smells earthy.
Avoid compost that’s still breaking down or has impurities.
2. Check your soil.
See if your garden soil needs compost. Signs of poor soil include low fertility, bad drainage, or it’s too packed.
3. Prepare the area.
If you’re starting fresh, mix compost into the soil at a 1:2-3 ratio (1 part compost to 2-3 parts soil). It boosts soil quality and gives vital nutrients.
For established ones, spread a 2- to 3-inch layer of compost on the surface. Don’t bury the plant stems.
3. Blend the compost with the soil.
Use a rake or garden fork to gently mix the compost into the top few inches of soil. This ensures it’s well integrated.
We recommend applying compost in early spring or late fall for best results, but it works anytime. After blending, think about using it as mulch around your plants to keep moisture in and weeds out.
4. Replenish as needed.
Make applying compost routine to keep soil fertility. Once or twice a year usually does the trick for most gardens.
5. Monitor your plants.
Keep an eye on your plants’ growth and health. Compost makes nutrients more available, leading to healthier plants.
Planter’s Tips
If you’re making your compost, learn the basics for a steady supply. Balance green and brown materials, turn the pile often, and keep it moist.
How much compost you need depends on your soil. Start with a moderate amount and adjust as needed for your garden.
Manure
| Factor | Description |
| Expertise Level | Easy to Moderate ●●○○○ |
| Suitable for | Vegetable gardens and fruit-bearing plants |
| Benefits | Provides essential nutrients including iron, enhances soil organic matter content |
| Possible Risks | Overapplication will lead to nutrient imbalances in the soil |
Animal manure from cows, horses, pigs, and chickens contains iron and other essential nutrients. Manure also enhances soil organic matter content.
How to Use Manure
1. Choose good-quality composted manure.
Look for quality manure from a reliable source in your area. Plus, the composting process removes harmful elements and weed seeds in the manure while breaking down nutrients for easier plant use.
2. Time the application.
Apply manure in the spring or fall when preparing for planting. Don’t use fresh manure during the growing season to prevent plant damage due to its high ammonia content.
3. Prepare the garden bed.
Get rid of weeds and debris. Make sure the soil is loosened enough to be well-draining and aerated.
4. Assess how much you need.
Calculate the amount of manure based on your garden bed’s size and your plants’ nutrient needs. Generally, you’ll need to apply about 1 to 2 inches of composted manure.
5. Layer on the manure and mix.
Spread the manure evenly across the garden bed, avoiding piles around the plant bases to prevent root issues and nutrient imbalances.
Gently mix the manure into the top few inches of soil using a garden fork or tiller. This ensures nutrients are incorporated into the plant’s root zone.
6. Monitor your plants.
Keep an eye on your plants for signs of nutrient problems. Adjust your manure usage in the following seasons based on your plant’s performance.
For safety, wear gloves when handling manure and wash your hands really well afterward to reduce the risk of contamination. Avoid using manure from animals treated with antibiotics or other medications.
Planter’s Tips
If you have fresh manure, compost it for a few months before using it in your garden. Store any leftover manure in a covered container or pile to prevent it from drying out or becoming too wet.
What causes iron deficiency in plants?
Plants usually lack iron due to three main reasons: high soil pH, low iron content in the soil, and nutrient imbalances affecting iron absorption. Let’s look at both in greater detail.
Iron Deficiency Due to High Soil pH
A high soil pH makes iron less available as the pH level goes up. High soil pH happens when you use too much lime without considering factors like your soil type (clay, loam, sand), its current pH, and your desired pH.
Using water with a high pH count for extended irrigation also raises soil pH. You can lower soil pH by adding sulfur or using iron sulfate to increase iron levels in your soil.
Iron Deficiency Due to Insufficient Iron in Soil
When crops are grown without using crop rotation and nutrients aren’t replenished through compost and fertilizers, the soil will have iron content issues. Overwatering makes this problem worse by washing away the water-soluble nutrients.
Some plants like azaleas, rhododendrons, and blueberries tend to suffer from iron deficiency due to this situation.
Iron Deficiency Caused by Nutrient Imbalances
Having too much of one nutrient messes up the absorption of another. If there’s too much phosphorus in the soil, it stops the plants from getting iron, even if iron’s already in the soil.
Most of the time, this happens because of homeowners using too many high-phosphorus fertilizers. This is especially glaring if your nitrogen-phosphorus-potassium (NPK) ratio has a high phosphorus number.
Having too much phosphorus also stops the production of phytochelates, which are needed for iron to be absorbed. That’s why when choosing a fertilizer, go for one with less phosphorus.
Can excessive iron harm plants?
Yes, plants can suffer from iron toxicity when there’s an excess of iron in the soil. Symptoms include leaf discoloration (bronzing) and stunted root growth.
Excessive iron content in your soil causes issues in nutrient absorption, even when the nutrients are available. You can do a soil test before adding supplements to confirm an iron deficiency.
A soil test can identify if your soil is too acidic (low pH) or too alkaline (high pH), guiding your supplement choices.
