Our Testing Approach
We ran parallel Kratky grows of butterhead lettuce (same seed batch, same light, same system design) using five different nutrient formulas at manufacturer-recommended rates for leafy greens. Water source: Melbourne tap water (EC 0.2, pH 7.3) adjusted to pH 6.0. EC target: 1.4 mS/cm for all formulas.
We measured: days to transplant size, fresh weight at harvest, root development (rated 1–5), tip burn incidence (common with calcium-deficient formulas), and flavour (rated blind by 6 household tasters).
Key Findings
The results confirmed what commercial lettuce growers have known for decades: calcium availability is the critical variable for hydroponic lettuce. The formulas that explicitly account for calcium delivery — either through calcium nitrate additions or calcium-chelated formulations — produced uniformly superior results in both tip burn prevention and flavour.
The cheapest formula (Generic nutrient powder, $12) produced acceptable lettuce but with 40% tip burn incidence and measurably lower fresh weight than the top performers. The most expensive formula (Canna Aqua Flores, typically used for fruiting crops) was optimised for fruiting and performed no better than mid-range leafy green formulas for lettuce — proof that crop-matched formulas matter.
The best balance of performance, ease of use, and cost for Australian lettuce growers remains General Hydroponics MaxiGro — simple, effective, widely available, and specifically calibrated for leafy vegetative crops.