A cannabis nutrients schedule is a week-by-week feeding plan that adjusts nutrient strength and NPK ratio to each stage of growth. Seedlings get a quarter-strength feed, vegetating plants get nitrogen-heavy grow nutrients, flowering plants switch to phosphorus and potassium, and the final one to two weeks are plain water. Matching the schedule to the stage prevents both nutrient burn and nutrient lockout.

What does a basic week-by-week cannabis nutrients schedule look like?

Most growers divide the cycle into four feeding phases: seedling, vegetative, transition, and flower. Each phase changes the concentration of the same base nutrients rather than requiring a completely new product line. A general-purpose grow and bloom pair covers the whole cycle.

• Week 1-2 (seedling): plain water or a quarter dose of grow nutrients. The plant lives off its seed reserves at first.
• Week 3-6 (vegetative): full-strength grow nutrients with a nitrogen-forward ratio. Feed at every other watering.
• Week 7 (transition): blend grow and bloom nutrients at roughly half of each. Stretch and pre-flower begin here.
• Week 8-12 (flower): bloom nutrients with added phosphorus and potassium. Reduce nitrogen as buds stack.
• Final 7-14 days (flush): pH-adjusted water only. This clears residual salts from the root zone.

What NPK ratio should you use at each stage?

NPK numbers on the label describe the percentage of nitrogen, phosphorus, and potassium by weight. Vegetative formulas usually sit near a 3-1-2 ratio, while bloom formulas run closer to 1-3-2 or 1-4-4. Cannabis also needs calcium, magnesium, and micronutrients like iron and zinc, which most base nutrient lines include.

Do you need extra calcium and magnesium?

Under LED lights or in coco coir and reverse osmosis water, a cal-mag supplement is often necessary. Coco coir holds calcium tightly, so plants can show deficiency within weeks without a supplement. Add it from the vegetative stage onward unless your base nutrients already supply enough.

How strong should the nutrient solution be?

Growers measure strength as electrical conductivity (EC) or parts per million (PPM). A useful starting range is 0.6 to 1.0 EC for seedlings, 1.2 to 1.8 EC during vegetative growth, and 1.6 to 2.4 EC in mid-flower. Landrace and CBD-dominant cultivars often prefer the lower end of each range.

Increase the dose by about 10 to 15 percent per week instead of jumping to full strength. Watch leaf tips for browning, which signals the mix is too hot. A quick runoff EC check tells you whether salts are building up in the medium.

What pH should nutrient water be?

Nutrients are only available to roots within a narrow pH window. Soil growers should target 6.0 to 6.5, while hydroponic and coco growers should aim for 5.5 to 6.2. Always measure pH after mixing nutrients, since concentrated formulas shift the reading.

How often should you feed cannabis?

In soil, a feed-water-water rotation prevents salt buildup and gives roots a break. In coco or hydroponics, plants can be fed at every irrigation because the medium drains freely. Adjust frequency by runoff EC and by how quickly the medium dries back.

Do CBD and hemp plants need a different schedule?

Hemp and high-CBD cultivars follow the same stage logic but generally tolerate lower nutrient concentrations. Many CBD-dominant genetics are grown for flower, so a slightly reduced nitrogen load in late flower supports resin development. Start at 75 percent of a standard schedule and adjust from there.

Common cannabis nutrient mistakes

• Feeding full strength before the plant has a developed root system.
• Mixing nutrients in the wrong order, which can cause precipitation and lockout.
• Ignoring pH after adding supplements.
• Skipping the flush, which leaves a harsh taste in the finished flower.
• Changing multiple variables at once, making problems hard to diagnose.

Should you follow the bottle label or your plants?

Manufacturer charts are starting points, not fixed rules. Plant response, medium type, light intensity, and cultivar all shift the correct dose. Keep a simple log of EC, pH, and dose each week so you can repeat what worked.