In the world of cultivation, some nutrients steal all the spotlight… (yes, we’re looking at you, NPK). Meanwhile, others quietly play a crucial role behind the scenes.
That’s exactly the case with calcium and magnesium: two key macronutrients that are frequently underestimated but can make a huge difference to plant health, growth, and overall crop quality.
In this blog, we explain why they are so important, when they may be lacking, what symptoms they cause and, above all, how to prevent deficiencies with ATA CALMAG and VGN CALMAG, Atami’s additives designed to meet precisely these needs.
Contents
1. Functions of Calcium in Plants and Signs of Deficiency
2. Functions of Magnesium in Plants and Signs of Deficiency
3. Why Calcium and Magnesium Deficiencies Happen in Modern Cultivation
4. Why You Should Use ATA CALMAG or VGN CALMAG
Functions of Calcium in Plants
Did you know that calcium acts like the “cement” of your plants?
Even though it doesn’t directly participate in photosynthesis, calcium is essential for maintaining the structure and overall health of your crop. It’s far from a filler nutrient — it plays a critical role in ensuring that plant cells function properly and can defend themselves against stress.
What does calcium do for plants?
• Cell structure: Calcium is a key part of plant cell walls, giving them rigidity and strength. A plant without calcium is, quite literally, a soft plant.
• Root development: It supports the formation and elongation of young roots, improving water and nutrient uptake.
• Cell division and elongation: No calcium, no growth.
• Enzyme activation: Many internal plant reactions require calcium to kickstart key biological processes.
• Stress resistance: Well-structured plants are better equipped to handle drought, heat stress and pathogens.
Calcium deficiency symptoms in plant leaves
Unlike magnesium, calcium is not very mobile within the plant. That’s why the first signs of deficiency appear in new growth and at shoot tips:
• Deformed new leaves, often with curled or sticky edges
• Necrosis on leaf margins; brown, dry spots that spread from the edges
• Burnt or dead leaf tips
• Stunted growth in young shoots
• In fruits: blossom-end rot (especially in tomatoes), cracked skins, or visible deformities
Learn more about calcium deficiency and functions here.
Functions of Magnesium in Plants
What does magnesium do for your crop?
Magnesium (Mg) is one of those nutrients that often goes unnoticed… until it’s missing. And when it’s missing, your plants feel it fast.
Here are its key roles:
• Central component of chlorophyll
It’s quite literally the heart of the molecule that allows the plant to photosynthesise. Without magnesium, your plant can’t turn light into energy.
• Involved in sugar and protein production
Magnesium activates many enzymes related to metabolism, energy transfer and the formation of carbohydrates essential for plant growth.
• Helps phosphorus uptake
Phosphorus is crucial for developing strong roots, flowers and fruits — but its absorption is limited if magnesium is lacking.
• Supports internal nutrient transport
Magnesium helps move other nutrients throughout the plant, promoting balanced development and healthy growth.
Magnesium deficiency symptoms in plant leaves
• Interveinal chlorosis: Leaves turn yellow between the veins, while the veins themselves remain green.
• First appears on older leaves: Since magnesium is a mobile nutrient, the plant redirects it to new growth, leaving older leaves visibly affected — as you can see in the image below.
• Advanced deficiency can lead to necrosis and premature leaf drop.
• Reduced yield and quality, especially in demanding plants or during late flowering.
Learn more about magnesium deficiency and functions here.
When can calcium and magnesium deficiencies occur?
There are several situations where these secondary nutrients become absolutely critical:
• Fast-growing or high-yielding crops: Vigorous plants with rapid growth or heavy fruiting (like tomatoes, peppers or flowering potted plants) often consume more calcium and magnesium than a standard base fertiliser can provide.
• Coco-based substrates: Coco has low buffering capacity for calcium and magnesium, making supplementation essential to avoid deficiencies.
• Irrigation with reverse osmosis, distilled or rainwater: These types of water contain very low levels of minerals — especially calcium.
• LED lighting: Under LED grow lights, plants photosynthesise more efficiently and have faster metabolism. This increases their demand for calcium and magnesium, particularly during the flowering stage. When LED growing, adding a calcium and magnesium supplement becomes a must.
• Nutrient competition: An excess of certain elements can interfere with uptake:
o High potassium levels can block magnesium absorption.
o Too much phosphorus competes with calcium.
o Sodium in hard or saline water also makes nutrient uptake more difficult.
• Acidic or heavily leached soils, where magnesium is easily washed away.
💡 The key is prevention
Even if your base fertiliser includes calcium and magnesium, these conditions often require an extra boost. These elements don’t accumulate easily, and their deficiency quickly impacts plant health.
Using targeted supplements like ATA CALMAG or VGN CALMAG helps cover this increased demand and prevents nutrient lockouts or imbalances.
These are CalMag products for plants designed to restore balance and boost your crop’s health.
Why use ATA CALMAG or VGN CALMAG? The calcium and magnesium your crop needs for a healthy and abundant harvest.
When your plants get enough calcium and magnesium, they grow stronger, develop greener leaves, produce healthier flowers and yield tastier fruits. These two nutrients are essential for:
• Vigorous vegetative growth
• Smooth flowering without deficiencies
• Improved nutrient uptake and energy production
That’s why supplementing with a calcium and magnesium product is often a smart move — especially if you’re growing fast, under lights or in coco.
At Atami, we make it easy for you with two CalMag solutions tailored to different growing styles:
A fast-acting mineral boost with calcium, magnesium and iron. A versatile solution that tackles three common deficiencies in one go.
Perfect for:
• Growing in coco or hydroponic systems, where calcium and magnesium retention is limited.
• Using reverse osmosis, rainwater or soft water, which are naturally low in minerals.
• The vegetative phase, especially if plants are weak or under stress.
Recommended dosage: 0.1 – 1 ml/L, depending on water quality and deficiency level.
Fully compatible with all Atami mineral feeding programmes.
A 100% organic CalMag additive with no nitrogen, part of Atami’s new VGN range — perfect for growers seeking a natural, sustainable boost.
Perfect for:
• Organic farming and living soils.
• Systems that support beneficial soil microbes.
• The flowering phase, thanks to its nitrogen-free formula.
Recommended dosage: 1 – 2 ml/L, depending on crop type and stage.
Certified organic. Zero nitrogen. Respects the soil’s natural balance, what more could you want?
When to apply CalMag?
• Preventively, in demanding crops, under LED lighting, in coco substrates, or when watering with low-mineral water.
• To correct deficiencies, when early symptoms appear (chlorosis, dry tips, poor vigour).
• As an occasional boost, if nutrient uptake isn’t as strong as it should be.
Final thoughts: Complete nutrition starts with the essentials
Calcium and magnesium are more than just secondary nutrients — they’re the invisible support structure that keeps your plants healthy, strong and productive. Without them, photosynthesis, cell division and nutrient absorption can’t function properly.
That’s why if you grow in coco, use soft water or rely on LED lighting, CalMag supplementation isn’t optional — it’s a smart investment in your crop’s success.
👉 ATA CALMAG and VGN CALMAG are essential allies in avoiding the nutrient deficiencies that could hold your grow back.
Start using them today and give your plants the extra edge they need to thrive.
Your plants (and you) will thank you.
