Best Hydroponic Nutrients for Lettuce (2026)

Lettuce is forgiving, but bad nutrients still ruin a crop. Tip burn, bolting, weak heads — almost always nutrients (or the pH of the nutrient mix). These three are what we actually use across our systems.

The short answer

• Easiest: General Hydroponics MaxiGro — one scoop, done.
• Best yield: General Hydroponics Flora Series (3-part).
• Cheapest per gallon: Masterblend 4-18-38 + cal-nitrate + epsom — the lettuce-farm staple.

Lettuce nutrient targets

• EC: 1.0–1.4 mS/cm. Push past 1.6 and you'll see tip burn.
• pH: 5.8–6.2. Below 5.5 and calcium uptake crashes.
• Temp: Keep reservoir under 72°F. Warm water + lettuce = root rot.

The rookie mistake

Don't keep topping up with plain water as the reservoir drops. The salt concentration climbs every cycle and you'll get tip burn by week three. Every two weeks: drain, rinse, refill with fresh nutrient solution.

Do I need Cal-Mag?

Only if you're using RO or distilled water. Tap and well water usually have plenty of calcium and magnesium. If your leaves cup downward and the new growth looks pale, add 1 mL/gal Cal-Mag and the problem disappears in days.

Related guides: Hydroponic Nutrients Explained · pH and EC for Hydroponics · how-to-grow-lettuce-hydroponically

What a lettuce-only feeding schedule looks like

Lettuce is one of the few crops where you can run a one-bottle nutrient for the entire life of the plant without sacrificing yield. After three years of side-by-side trays, our standard recipe is dead simple: General Hydroponics MaxiGro at 1.0 g per litre from transplant through harvest, with a top-up to 0.6 g/L whenever the EC drops below 1.0.

The temptation as a beginner is to push EC higher because "more food = more growth". Lettuce punishes that instinct with tip burn and bitter leaves. We have measured noticeably bitter heads at sustained EC above 1.8, and our blind taste-tests confirmed it every time.

Masterblend versus MaxiGro for home growers

Masterblend 4-18-38 is the darling of commercial lettuce farms because it works out at pennies per gallon. For one or two trays at home, the saving is rounding error — under £10 a year — and you pay for it in faff: three separate components, careful order of mixing to avoid lockout, and a precision scale to weigh sub-gram quantities. We use Masterblend when we run a six-tower test rack, MaxiGro for everything else.

The Cal-Mag question for soft-water cities

If your tap water tests under 100 ppm (much of Scotland, parts of Wales, large stretches of the US Pacific Northwest), your lettuce will eventually show pale new leaves and curled edges — classic calcium and magnesium deficiency. Add 0.5 ml/L of any Cal-Mag supplement and symptoms reverse within a week. Hard-water cities (London, much of the US Midwest) can usually skip it.

Frequently asked questions

Keep reading