What is fertilizer, and why do cannabis plants need it?

Fertilizer provides essential nutrients like nitrogen, phosphorus, and potassium to help cannabis plants grow strong, healthy, and produce high yields. In most grow setups, regular feeding is required to avoid deficiencies and promote optimal growth.

What nutrients are essential for healthy cannabis growth?

Cannabis needs macronutrients like nitrogen, phosphorus, and potassium, plus secondary nutrients like calcium, magnesium, and sulfur. Micronutrients such as iron, zinc, and boron are also vital for plant health and development.

When should I start feeding cannabis plants nutrients?

Start feeding once your cannabis seedlings develop their first true leaves. In coco or hydro, feeding may begin as early as day 7–10. In soil, wait until the plant shows signs of slowed growth or pale lower leaves.

What do NPK values mean on cannabis fertilizer?

NPK stands for Nitrogen (N), Phosphorus (P), and Potassium (K), the three primary macronutrients. Ratios like 3-1-2 or 1-4-5 guide what stage of growth the fertilizer supports—veg or bloom.

How do I know if my cannabis plant is overfed or underfed?

Check the EC/PPM of your runoff water. If it's much higher than your input, nutrients are building up—overfeeding. If it's much lower, your plant may be hungry—underfeeding.

PAR Map Visualizer

Light. Data. Growth. Smarter cultivation starts here.

PAR Map Visualizer

Enter your PAR readings to generate a heatmap of your grow area. [?] PPFD Calculator ↗

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Grow Journal

Track light coverage, note hot spots, and save your readings with the Grow Journal.

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What is a PAR Map?

A PAR map shows how evenly light is distributed across your grow space.

How to Take PAR Readings

Use a PAR meter at each grid point (3×3, 4×4, etc.)
Keep the meter at canopy height
Record values at consistent spacing

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PPFD Calculator
DLI Calculator
Wattage Calculator

Tool by GrōHaus — helping growers dial in their light, space, and yield.

PAR Map Visualizer

PAR Map Visualizer

Grow Journal

What is a PAR Map?

How to Take PAR Readings

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