Irrigation Cycle Planner Calculator

Irrigation Cycle Planner

Three tools in one: find your daily irrigation frequency, calculate the right shot size per event, and get exact pump run times — for coco, rockwool, perlite, and clay pebbles. Need help choosing a timer or drip system? Talk to a Grow Expert.

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Irrigation Cycle Planner

Choose a tool: Cycle Frequency — how many times per day  ·  Shot Size — how much per event  ·  Run Time — how long to run the pump.

Tip: Select your medium and growth stage to get a recommended daily irrigation schedule — including suggested times throughout the day.
How to use this planner
  1. Tab 1 — Cycle Frequency: Select your medium, growth stage, photoperiod, and VPD to get a recommended number of daily irrigations and suggested event times.
  2. Tab 2 — Shot Size: Enter container volume and target runoff % to get the right volume per irrigation event. Use the cycle count from Tab 1 for daily totals.
  3. Tab 3 — Run Time: Plug in your shot size (from Tab 2), emitter GPH, and emitters per plant to get your pump run time in minutes:seconds.
  4. Set your timer: Program a repeat-cycle timer with your run time and interval. For first runs, check runoff percentage and adjust shot size up or down by 10%.

Key principle: More frequent, shorter irrigations outperform fewer longer ones. Smaller shots maintain better oxygen in the root zone and prevent nutrient channeling.

Runoff targets: Maintenance 10–15% · Salt flushing 20–30% · Early propagation 0% (no runoff until roots establish)

📅 24-Hour Irrigation Schedule — Visual Timeline Timeline ▾

Lights-on window

Irrigation event

Dryback period

Run the Cycle Frequency calculator above to see your daily schedule plotted across a 24-hour period.

Irrigation Quick Reference — By Medium

Starting points only. Adjust based on observed runoff, plant size, VPD, and growth stage. Always verify with a calibration bucket.
Medium Cycles/Day (Veg) Cycles/Day (Flower) Shot Size Target Runoff Dryback Target
Coco coir 3–5× 5–8× 10–15% container vol 10–20% 15–25% overnight
Rockwool / Stonewool 4–6× 6–10× 6–10% slab vol 10–20% 20–30% overnight
Perlite / Perlite-coco 4–6× 6–9× 10–15% container vol 15–25% 25–35% overnight
Clay pebbles (Hydroton) 6–12× 8–14× Until saturation 20–30% Significant — dries fast
Soil / Promix 1–2× 1–3× Until 10–15% runoff 10–15% Near dry before rewater

Frequently Asked Questions

How many times a day should I irrigate coco coir?
Coco coir typically needs 4–8 irrigation events per day during peak flower, with shorter more frequent shots outperforming fewer long ones. In early veg, 2–4 times per day is sufficient. The goal is to maintain 35–65% volumetric water content and achieve 10–20% runoff per event. Higher VPD days (above 1.3 kPa) may require an extra cycle to keep up with transpiration demand.

What is the correct shot size for drip irrigation in hydroponics?
Shot size should deliver 10–20% of your container volume per event, targeted to produce 10–20% runoff. For a 3-gallon coco bag, that's roughly 48–77 oz (1.4–2.3 L) per irrigation. Start at 10% and increase if runoff is below target. Smaller, more frequent shots maintain better dissolved oxygen in the root zone than large infrequent floods.

How long should my drip irrigation pump run per cycle?
Run time = shot volume ÷ emitter output. If you need 48 oz per plant with a 2 GPH emitter, that's (48 ÷ 128) ÷ (2 ÷ 60) = 11.25 minutes. Always verify with a calibration test — fill a measuring cup for 60 seconds then multiply by 60 to confirm actual GPH. Line pressure variations can cause real output to differ from rated GPH by 15–20%.

Should I irrigate during lights-off?
Generally no. Plants stop transpiring in the dark period, so the medium stays wet longer and dissolved oxygen levels drop. Most growers start their first irrigation 1–2 hours after lights on (once transpiration demand picks up) and end their last event 1–2 hours before lights off to allow a controlled overnight dryback. Rockwool and perlite users typically target 20–30% dryback by lights-on the next day.

Automate your irrigation schedule.

Shop repeat-cycle timers, drip emitters, manifolds, and complete fertigation systems.
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