Hydroponic Additives & Supplements

What an additive does that a base nutrient does not

A base nutrient is complete: NPK plus the trace elements, balanced for a whole growth stage, and on its own it will finish a crop. An additive is deliberately incomplete and does one job hard — lift calcium and magnesium, deliver silicon, push PK through peak flower, feed the biology in the root zone, or strip the system out before harvest.

That is why additives stack and base feeds do not, and why the ones you need depend on your water, medium and light rather than on the label.

Our range of additives and supplements

Cal-mag and secondary minerals

What a base feed most often runs short of, and the first thing to check when new growth pales or leaf edges crisp. The cal-mag range spans Athena, Canna, Flairform CMX, FloraMax Ca-Mg-Fe, Green Planet Pro Cal, Med Tek and Plant Mechanics Super N+, from 250mL up to 18.9L.

Silica

Two different products sold under one word. Silicate supplements in the silica range — Growth Technology GT Silica, Cyco, FloraMax, Flairform Silika Majic, Hy-Gen Budlink — come in litre bottles, dosed by the millilitre. Mono-silicic acid concentrates such as Plant Mechanics Super Si and Bio Diesel Pathway 40% arrive in 100mL bottles, dosed in drops. Never carry one dose rate across to the other.

Flowering, PK and bud boosters

The largest group on this page. Flowering additives run from straight PK lifts — Canna PK 13/14, Green Planet PK Spike, Athena PK, Cyco Potash Plus — through resin and carbohydrate products like Green Planet Rezin and FloraMax Resin-XS, to House & Garden Top Booster, Shooting Powder and Atami Bloombastic.

Vegetative and grow-stage additives

Veg-stage products push leaf and stem rather than flower. Grow additives include Professor's Grow Fast and Go Green, Cyco Grow XL, FloraMax Growth-XS, Plant Mechanics LED Fuel, and Growth Technology's single-element liquids — Nitrogen, Potash, Phosphorus, Iron and Trace Elements — which correct one element without moving the rest of the feed.

Root stimulants and propagation

These go in at transplant or into a cloner. The root stimulator range includes House & Garden Roots Excelurator, Canna Rhizotonic, Growth Technology Rootzone and Clonex, Atami Rootbastic, FloraMax Root-XS and Cyco Ryzo Fuel.

Microbes, enzymes and system cleaners

Biology rather than chemistry. Microbes and beneficial bacteria covers mycorrhizal inoculants (Xtreme Gardening Mykos, Plant Success Great White, SNT Mycobiome), bacterial products (Impello Tribus Original, Mammoth P, BBA Max Roots, Azos) and trichoderma, plus enzymes — Canna Cannazym, House & Garden Multizyme, Cyco Zyme.

Foliar sprays and soil amendments

Some additives never reach the reservoir. Foliar sprays — Optic Foliar Transport and Switch, Growth Technology GT Foliar Spray, Accent Green-Up, Bloom Florigen — go on the leaf. Soil additives are worked into the medium: SNT worm castings and insect frass, De-Ozzy soil conditioner, BIOCARBON biochar in 3L, 9L and 25L bags.

How to choose an additive

1. Fix the deficiency before chasing the yield. A cal-mag or silica gap costs you more than a bloom booster will ever add. Sort the base feed first.
2. Match it to your medium and your water. Coco and rainwater raise cal-mag demand; soil on hard tap water often does not. Enzymes and cleaners suit recirculating hydro more than hand-watered soil.
3. Read what your base feed already contains. Several two- and three-part sets already carry a PK lift or added calcium. Stacking another on top is how growers reach lockout instead of bigger flowers.
4. Add one at a time. One new additive per run. Three at once tells you nothing about which one worked.
5. Check the size ladder before you commit. Most lines here run 250mL, 1L, 5L and 20L; Athena runs 0.9L, 3.8L and 18.9L. Buy small for the trial run and step up once it earns a place.

Where to start

Three additives cover most first-time problems: a cal-mag, a silica, and a root stimulant. Add a flowering booster once those are dialled in. Still choosing a base feed? Start with the full nutrient range and The 5 Best Hydroponic Nutrients Australia. Yellow Leaves on Plants? covers the deficiencies these additives are usually bought to fix; Organic vs Synthetic Nutrients covers the organic-versus-mineral choice.