Frequently asked questions

• What is Dutch Pro's CalMag and when do I need it?

  It's a specialised calcium and magnesium supplement designed to prevent and correct deficiencies in these two critical secondary macronutrients. Even though base nutrients already contain calcium and magnesium, circumstances such as RO water or poor substrates call for extra supplementation.

• How do I recognise a calcium or magnesium deficiency?

  A lack of calcium shows up as deformed new leaves, aborted flowers or blossom-end rot. A magnesium deficiency causes yellowing between the leaf veins, known as interveinal chlorosis, while a nitrogen deficiency shows up as loss of vigour and slow growth.

• What dose of CalMag should I use?

  The range goes from 0.1 ml per litre as light maintenance with hard water or a rich substrate, through 0.5 ml per litre as the standard dose for most cases, up to 1 ml per litre for a full correction. With RO water or very soft water, it's recommended to use 0.8 to 1 ml per litre continuously.

• When is it worth going up to the maximum dose?

  When you see visual signs of deficiency, for 2 or 3 weeks, and during heavy flowering from weeks 4 to 7, when flower demand increases. Also during recovery from heat or water stress, since magnesium uptake gets blocked under stress.

• What is CalMag's composition?

  It provides calcium and magnesium as its primary ratio, in soluble, chelated form for maximum availability, with an optimised Ca:Mg balance. It also includes 5% nitrogen to support protein synthesis, with only trace amounts of phosphorus and potassium so it doesn't interfere with your base nutrients.

• What other Dutch Pro additives does it combine well with?

  With Silica Von Liebig, since silicon improves calcium absorption, and with Explode during flowering to maximise flower production. Also with Amino Strength, whose amino acids improve the transport of calcium and magnesium within the plant.