Magnesium Sulphate 1 kg

The basis of photosynthesis, within reach of every grower. Granular magnesium sulphate, with a composition of 16% MgO / 32% SO₃, is the central macronutrient of chlorophyll – without magnesium, plants cannot photosynthesise efficiently, compromising all growth and production.

Sold in a 1 kg pack, it is ideal for supplementing or adjusting the magnesium in the nutrient solution of any hydroponic system – especially tomato crops, where magnesium deficiency is the most common nutritional disorder.

Technical Features

• Nutrient: granular magnesium sulphate
• Composition: 16% MgO (magnesium) / 32% SO₃ (sulphur)
• Pack: 1 kg
• Average dose: 400–650 grams per 1000 litres of water in the tank
• Form: granules – dissolve easily in water

What does magnesium do for plants?

Magnesium is the only macronutrient that is a direct part of the chlorophyll molecule – it is literally the central atom that captures sunlight for photosynthesis. But its roles go much further:

• Central component of chlorophyll – no efficient photosynthesis without magnesium
• Gives leaves their green colour – chlorosis (yellowing) is the first visible sign of deficiency
• Activates enzymes essential to the plant’s energy metabolism
• Improves fruit quality – reduces misshapen fruit and blossom-end rot
• Evens out ripening – plants with enough magnesium ripen more uniformly, making harvest easier
• Highly mobile in the plant – can be moved from old leaves to new ones if deficient

How do you control these parameters?

Nutrient solution

The plant consumes the solution, and every day the volume in the tank drops. This volume should be topped up every day with water, not with nutrient solution. Plants absorb much more water than nutrients, and since the nutrient solution is saline, topping up with solution every day salinises it until the dissolved salts exceed what the roots can tolerate. If this happens, plants stop growing – not from a lack of nutrients, but because of an excessively high osmotic potential at the roots.

Control the pH of the nutrient solution

As they take up nutrients, plant roots change the pH of the nutrient solution. The pH indicates how acidic or alkaline the nutrient solution is. Plants develop best between pH 5.5 and 6.5, and as they grow they change the pH of the solution. That is why the pH should be measured every day after topping up the solution with water. If it is outside the 5.5–6.5 range, adjust it with acid if above 6.5, or with base if below 5.5.

Control the electrical conductivity of the nutrient solution

As plants grow, the nutrients in the solution are used up and the solution becomes depleted. Eventually the solution can no longer supply the nutrients the plants need. At that point the solution should be replaced. One of the biggest problems is knowing when to change it.

A solution containing salts (nutrients) can conduct electric current. The higher the concentration of dissolved salts, the greater this conductivity. So a drop in electrical conductivity tells you when the nutrient solution needs changing. The easiest way to know the nutrient concentration is to use a conductivity meter.

One of the main reasons growers choose water-culture systems is that growth and maturity are usually 15–25% faster. Growers can still reach the desired plant size with a short vegetative period. So to get optimal early production from these systems, using the right nutrient mix and having the right conditions matter far more.