Iron Deficiency (usually pH Lockout)

New / upper growth is pale yellow to almost white while older leaves stay green. Iron is immobile - the newest growth shows the shortage first. Indoors this is almost always a pH lockout rather than a real iron shortage. Fix pH and uptake usually recovers within a few feeds.

What usually causes it

• pH above 6.5 in soil or above 6.2 in coco/hydro (Fe becomes unavailable as pH rises)
• Root rot or anaerobic root zone preventing uptake
• Very cold root zone (below 18 C) slowing transport
• High phosphate or excess Cu/Mn antagonising Fe
• Genuine Fe shortage in unbuffered RO water (less common)

Related product categories

• pH Adjusters
• Additives & Boosters
• Root Stimulators & Beneficials

Terms worth knowing

• pH

Walk the questions if you are not sure this is the match. The notes above are the same ones the tool ends on.