Magnesium (Mg) is an important element for plant growth, but Minnesota doesn’t put much emphasis on using it in fertilizer programs. This lack of attention is understandable for most of the state; most Minnesota soils have enough magnesium to meet crop needs when they are managed correctly. If Mg is limited in the diet, animals can develop grass tetany. Therefore, some special consideration is given to the Mg status of forage crops.
As a gardener, you likely know the importance of providing key nutrients like nitrogen, phosphorus, and potassium to help plants grow strong and healthy. But did you know that magnesium is another mineral that’s vital for plants? Many gardeners are now turning to magnesium supplements as an easy and affordable way to give plants a nutritional boost.
In this article, we’ll explore the benefits of using magnesium tablets for plants, provide tips on safe and effective application, and answer common questions about this gardening hack. Let’s dive in!
Why Plants Need Magnesium
Magnesium plays several crucial roles in plant growth and development:
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It’s a key component of chlorophyll, the green pigment essential for photosynthesis. Without adequate magnesium, plants cannot properly carry out photosynthesis.
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It helps activate important plant enzymes needed for growth processes
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It contributes to the structural development of plant proteins, DNA, and RNA.
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It aids in the uptake and transport of other key nutrients like phosphorus
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It helps plants synthesize and metabolize nutrients absorbed from the soil.
Signs of Magnesium Deficiency
Plants lacking sufficient magnesium typically show these deficiency symptoms:
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Interveinal chlorosis – yellowing between leaf veins while veins remain green
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Stunted growth and smaller leaves
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Leaf tips and margins turn reddish, then brown
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Leaves curling or cupping
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Poor flowering and fruit set
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Increased susceptibility to stress and disease
Why Use Magnesium Supplements?
With those key roles in mind, ensuring adequate magnesium for your plants is crucial. While magnesium is found naturally in many soils, levels can deplete over time. And sandy or acidic soils are prone to magnesium deficiencies.
Fertilizers also don’t always contain significant magnesium. This is where magnesium tablets can be helpful!
Reasons to consider magnesium supplements:
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Convenient and affordable source of magnesium
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Allows precise control over magnesium levels applied
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Can quickly correct magnesium deficiencies
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Useful for container plants prone to mineral depletion
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An organic gardening option
Choosing a Magnesium Supplement
When shopping for magnesium tablets, look for 100% magnesium oxide or magnesium citrate formulas. Avoid formulas with added fillers, flavors, dyes, or other additives.
For easy mixing and application, powdered magnesium supplements are ideal. Tablets can be crushed into a powder as well.
The most suitable magnesium supplements will be labeled as highly soluble in water. This ensures the mineral can dissolve and be taken up by plants.
Finally, verify the magnesium concentration listed on the label. A higher percentage is better.
How To Apply Magnesium Tablets to Plants
Once you’ve chosen a suitable magnesium supplement, application is easy:
1. Mix with Water
Start by dissolving the magnesium powder (or crushed tablets) in water. Use a ratio of 1 teaspoon per gallon of water. Mix or shake well to dissolve.
2. Optional Acidification
You can add several drops of mild acid like lemon juice or vitamin C to the water. This slightly lowers the pH which helps magnesium dissolve and become plant-available.
3. Water Plants as Usual
Use your magnesium-infused water to irrigate plants as usual. The dissolved magnesium will be taken up by roots and leaves.
4. Repeat Regularly
Plants need a constant supply of magnesium. Repeat applications every 1-2 weeks.
5. Avoid Overdosing
Only apply at recommended rates, as too much magnesium can also harm plants.
6. Combine with Balanced Fertilizer
For overall nutrition, use magnesium tablets as a supplement to balanced fertilizer, not a replacement.
Magnesium Tablets for Garden Plants
Magnesium tablets can benefit plants in both outdoor garden beds and containers:
For gardens – Mix tablets into water and apply through irrigation systems or a watering can. Target magnesium-loving plants like tomatoes, peppers, and brassicas.
For containers – Container plants are especially prone to magnesium deficiency since they have limited soil. Dissolve tablets in water then use to water containers.
For lawns – Magnesium improves grass strength and color. Dissolve tablets in a tank sprayer and apply uniformly over the lawn.
For hydroponics – Add powdered magnesium supplements to your hydroponic nutrient solutions. This allows precise control over magnesium levels.
Magnesium Tablet Tips
Follow these tips for best results with magnesium supplements:
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Read and follow label directions carefully
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Test soil before applying to determine if magnesium is deficient
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Water in immediately after applying to prevent powder from blowing away
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Monitor plants and adjust rates accordingly
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Combine with other nutrients like nitrogen and phosphorus
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Apply at base of plants or leaves to promote rapid absorption
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Use more for magnesium-loving plants like tomatoes and brassicas
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Avoid applying to plants showing heat or water stress
Frequently Asked Questions
Here are answers to some common questions about using magnesium supplements from tablets in the garden:
Are magnesium tablets safe for all plants?
Magnesium is safe for most edible and ornamental plants. However, get guidance before applying to acid-loving plants like azaleas which prefer lower magnesium levels.
When should I apply magnesium to plants?
Early spring and throughout the active growing season are best. Avoid applying during dormancy or times of stress.
How often should I use magnesium tablets on plants?
Most plants need magnesium every 1-2 weeks. Monitor for deficiency signs and apply more or less frequently based on plant response.
What’s the best way to use magnesium on container plants?
Dissolve the recommended amount of magnesium powder or crushed tablets in water. Use this magnesium-rich water whenever you irrigate containers.
Can I use Epsom salts instead?
Yes! Epsom salt (magnesium sulfate) also provides magnesium in a water-soluble form that plants can use. Use similar mixing and application guidelines.
What concentration of magnesium should I use?
Avoid exceeding 5-10 ppm (parts per million) magnesium concentration in your plant watering solution. Start lower and increase within this range based on results.
Can too much magnesium harm plants?
Yes, magnesium toxicity can occur if over-applied, causing leaf burning, poor growth, and reduced flowering and fruiting. Excess magnesium interferes with calcium uptake.
How do I know if plants need more magnesium?
If you see interveinal leaf yellowing and stunted growth, especially on magnesium-loving plants, try supplementing with magnesium tablets.
Final Thoughts
Magnesium deficiency is easily corrected with magnesium supplements, allowing your plants to reap the many benefits of this mineral. Tablets and powders make it easy to precisely control magnesium levels.
Follow the tips in this guide to safely and effectively use magnesium tablets from your medicine cabinet or local pharmacy to boost your garden plants. The small upfront investment will pay off with healthier plants and improved yields!
Relationship of magnesium to calcium in soils Figure Magnesium deficiency in corn. The striping extends the full length of the leaf.
Some people think that soils should have a certain “ideal” amount of calcium to magnesium, and if they don’t have it, one of these two nutrients should be added to the fertilizer, Several studies in the Corn Belt that have looked into the importance of ratios have never found proof that this “ideal” ratio is needed. Different amounts of calcium and magnesium were added to soils in Wisconsin as part of a fertilizer program. This changed the ratio of calcium to magnesium in the soils from two to eight. This variation had no significant effect on alfalfa and corn yield. When fertilizer guidelines are made, the focus should be on making sure that soils have enough magnesium instead of keeping a certain ratio of one nutrient to another.
Magnesium is a mobile element in the plant and deficiency symptoms will occur first in the oldest leaves.
The loss of a healthy green color can be the first indication of a Mg deficiency. Color loss reflects the shortage of chlorophyll in the plant. The deficiency gets worse when the space between the leaf veins turns yellow while the veins stay green. In corn, each leaf has a clear stripe that runs the length of it and shows up first on the lower leaves (see Figure 2).
Magnesium in the soil
Magnesium is abundant in the earths crust. It is found in a wide variety of minerals. Magnesium becomes available for plant use as these minerals weather or break down. The majority of the soils in western Minnesota have naturally high levels of Mg. If dolomitic limestone is added to the crop rotation in the eastern counties’ acidic soils, it should provide enough Mg for plant growth.
Magnesium is held on the surface of clay and organic matter particles. Although this exchangeable form of Mg is available to plants, this nutrient will not readily leach from soils. The general relationship between forms of Mg in the soil is illustrated in Figure 1. Figure 1. A generalized soil magnesium cycle that shows where magnesium can be added to or taken away from the soil every year
In Minnesota, Mg deficiency has only been observed on very acid soils. These soils usually have a sandy loam, loamy sand or sand texture. A Mg deficiency is not likely to occur until the soil pH drops below 5. 5. In Minnesota, the acid sandy soils occur in the central and east-central part of the state.
Soils with low levels of Mg can happen when potatoes are grown on sandy, acidic soils or when corn is grown after potatoes. Grass tetany, a disease in animals caused by not getting enough magnesium in their food, has been seen in places where grass pastures have been treated with a lot of potash. But tests have shown that adding magnesium to a fertilizer plan for these pastures has not made them produce more forage. For these situations, it is less expensive to supplement the animal diet with a salt that contains Mg.