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.

What is a good DLI for cannabis?

For cannabis, a good DLI is: Seedlings: 10–15, Veg: 20–30, Flower: 30–50+ mol/m²/day.

How do I increase DLI?

To increase DLI, raise your PPFD (light intensity) or extend your daily light hours.

What if my DLI is too high?

If your DLI is too high, reduce your light intensity or shorten light hours. Watch for signs of light stress like leaf curling or bleaching.

What kind of grow light should I use?

We recommend full-spectrum LED grow lights for efficient and uniform light delivery.

DLI Calculator

Light. Data. Growth. Smarter cultivation starts here.

DLI Calculator for Cannabis Growers

Use this tool to calculate your Daily Light Integral (DLI) based on your average PPFD and daily light hours.

Average PPFD (µmol/m²/s) [?] Hours of Light per Day [?]

Grow Journal

Plan, track, and reflect on your grow. The Grow Journal helps you organize tools, notes, schedules, and specs — all in one place.

Learn About the Grow Journal Open Dashboard

What is DLI?

DLI (Daily Light Integral) is the total amount of light your plants receive in a day, measured in mol/m²/day. It combines light intensity (PPFD) and hours of exposure.

Ideal DLI Ranges

Seedlings: 10–15 mol/m²/day
Veg: 20–30 mol/m²/day
Flower: 30–50+ mol/m²/day

Helpful Tools

PPFD Calculator – Estimate µmol/m²/s for your light setup
Wattage Calculator – Estimate light output needs
Light Distance Calculator – Dial in hanging height

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