IONIC Tonic | Calcium & Magnesium Plant Feed by Growth Technology

IONIC Tonic – Calcium & Magnesium Plant Feed – Growth Technology

£21.99

Type: Mineral
Mineral feeds are dissolved minerals your plant can use straight away. They're fast-acting and precise, but it is possible to overdo them, so stick to the dose.

The Two Minerals Everybody Forgets

Ask most growers what plants need and they'll say nitrogen, phosphorus and potassium. Calcium and magnesium rarely make the list, right up until the leaves start yellowing between the veins or new growth comes through spotted and weak. By then the plant has been short for a while.

IONIC Tonic is the calcium and magnesium top-up in the 2026 IONIC range. A small, measured dose keeps both minerals available through the hungriest parts of the grow, and puts them back quickly when plants run short.

Why It Works

Calcium for structure: builds strong cell walls and sturdy new growth.
Magnesium for green: sits at the heart of chlorophyll, keeping leaves deep green.
Quick top-up: a targeted dose when Ca or Mg runs short.
Tiny dose: just 0.5–1ml per litre.

For Houseplant & Garden Growers

Watering with rainwater, filtered water or soft tap water? Growing in coco, or under LED lights? All of these can leave plants short of calcium and magnesium. A small splash of IONIC Tonic in the watering can puts them back.

For Growers

Use alongside any IONIC base feed. The dose depends on your medium:

Soil and soft-water hydro: 0.5ml/L from week 6 through flowering (weeks 6–10).
Coco: 1ml/L as a routine top-up from week 3 (weeks 3–10), because coco binds calcium and magnesium.
Hard water hydro: not part of the routine schedule. Use only if leaves show signs of running short, at 0.5ml/L for one week.

Rose's Pro-Tip: Add Tonic to your water on its own and stir before the base feed goes in. Concentrated calcium and other nutrients don't mix well neat.