A hydroponic schedule is really two schedules running together: the plant’s life stages and your reservoir routine. Get both on a calendar and most hydro problems become easy to catch early. This guide lays out a week by week plan for autoflowers and photoperiod plants, then shows how to test, adjust and troubleshoot your nutrient solution.

How the stages line up

The University of Saskatchewan’s cannabis guide, a Canadian university guide we use here for growing basics, gives the basic timeline. Seeds usually germinate in “between two and seven days,” and the seedling stage “usually lasts for about three weeks.” Photoperiod plants stay in vegetative growth until they get about 12 hours of uninterrupted darkness. Autoflowers start flowering by age, and the same guide notes many are “ready to harvest in 70-90 days.”

Stage	Autoflower	Photoperiod
Germination	Days 1 to 7	Days 1 to 7
Seedling	Weeks 1 to 3	Weeks 1 to 3
Vegetative	Weeks 3 to 5	Weeks 3 to 8 or longer, your choice
Flowering	Starts by age, about weeks 4 to 5	Starts after the switch to 12 hours on, 12 off
Harvest	Often 10 to 13 weeks from seed	About 8 to 10 weeks after the switch for most varieties, per USask

These are typical ranges. Your strain’s listing gives its own breeder stated flowering time.

Week by week feeding schedule

The University of Missouri Extension notes that “the optimum pH for most hydroponic crops is 5.5 to 6.5.” Purdue Extension, writing about soilless substrates rather than reservoirs, notes that “all nutrients are readily available at a pH of 5.4 to 6.2,” so treat that as a reference for growing media, not a reservoir target. The weeks in the table below follow a photoperiod plant with a short veg. Autoflowers move into flower earlier, around weeks 4 to 5, so shift them to the flower rows sooner. The EC column is an editorial example range only. Your nutrient brand’s label is the authority, and Missouri Extension warns that EC “does not confirm the concentration of individual nutrients.”

Week	Stage	pH target	Example EC (mS/cm)	Notes
1	Seedling	5.8 to 6.2	0.4 to 0.8	Quarter strength or less
2 to 3	Seedling	5.8 to 6.2	0.8 to 1.2	Raise slowly as new leaves appear
4 to 5	Vegetative	5.6 to 6.0	1.2 to 1.6	Grow formula
6 to 7	Early flower	5.8 to 6.2	1.4 to 1.8	Transition to bloom formula
8 to 9	Mid flower	5.8 to 6.2	1.6 to 2.0	Peak feeding if plants look healthy
10 and on	Late flower	5.8 to 6.2	Taper	Lower feed as harvest nears

For photoperiod plants, stretch the vegetative rows as long as you keep plants in veg, then start the flower rows from the light switch.

How to set up and run your hydro schedule

1. Test your source water. Missouri Extension lists optimum source water at pH 5.5 to 7, EC 0.2 to 0.8 dS/m (the same as 0.2 to 0.8 mS/cm, since 1 dS/m equals 1 mS/cm) and alkalinity 40 to 160 ppm. Purdue Extension, writing about soilless substrates, notes that high alkalinity “can increase substrate pH over time.”
2. Read your nutrient label. Missouri Extension’s process starts with researching your crop’s needs and calculating amounts before you mix.
3. Mix concentrates separately. If your nutrients come in two parts, add Part A to the water, stir, then add Part B. Missouri Extension explains that mixing the concentrates together can make calcium precipitate.
4. Measure pH and EC after mixing. Use a meter. Missouri Extension advises against pH strips for this work.
5. Adjust, then measure again. Change pH in small steps and retest each time.
6. Check oxygen and temperature. Missouri Extension notes that warmer water holds less oxygen, lists dissolved oxygen above 6 ppm as optimum, and says deep water culture growers must monitor oxygen and temperature.
7. Log every reading. Purdue Extension’s advice is to “track your values over time on a graph. This is the real value of testing.”

Meter care

Missouri Extension recommends calibrating weekly with pH 4 and pH 7 buffers, rinsing the probe with distilled water, and storing it in storage solution, never in plain water. It notes a pH probe lasts about 1 to 2 years and an EC probe about 2 to 5 years. Purdue Extension recommends meters with automatic calibration and temperature compensation and storing solutions and meters at room temperature.

Reservoir routine

• Daily: check water level, temperature and plant color.
• Every few days: measure pH and EC and write them down.
• Weekly: calibrate the pH meter.
• Regularly: drain and refresh the reservoir on the schedule your nutrient label suggests, and clean it between grows.

Harvest, drying and curing

Your schedule does not end just because the reservoir comes down. The University of Saskatchewan guide notes that most growers judge ripeness by the trichomes, which turn from clear to cloudy to amber, and that the best harvest window is short, about five days. It suggests drying in a dark room at about 61 to 73°F (16 to 23°C) with 50 to 60% relative humidity for about 10 to 14 days, until stems snap rather than bend. For curing, it describes sealing buds in jars and opening them two to three times a day for the first week, then once or twice a week for another two to four weeks.

Put those dates on the same calendar as your feeding weeks. Knowing when the dry room must be free is part of planning the next run, and it keeps your hydro system from sitting idle between grows. Clean and sanitize the reservoir, pump and lines while the harvest dries, following the equipment and sanitizer label directions, so the next seedlings start in a fresh system.

Troubleshooting

Symptom	Possible cause	What to do
pH drifts up every day	High alkalinity in source water	Test source water and adjust. Purdue notes alkalinity can raise substrate pH over time
EC climbs while water level drops	Plants drinking more water than nutrients	Top off with plain pH adjusted water
EC falls fast	Plants feeding heavily	Raise strength in small steps, within label limits
Roots brown and slimy	Warm water and low oxygen	Cool the reservoir and add aeration. Missouri notes warm water holds less oxygen
Leaf tips burned	Solution too strong	Check pH, source water and the nutrient label, then lower EC if the mix is too strong
Readings jump around	Meter out of calibration	Calibrate with pH 4 and 7 buffers and replace an old probe

To pick strains with known timing for your calendar, see our indica autoflower comparison at https://kindseed.com/top-10-indica-autoflower-strains-on-kindseedcom/, and for terms see our cannabis glossary at https://kindseed.com/cannabis-glossary/.

Sources: University of Missouri Extension G6984, Hydroponic Nutrient Solutions (https://extension.missouri.edu/publications/g6984). Purdue Extension HO-237, pH and Electrical Conductivity Measurements in Soilless Substrates (https://ag.purdue.edu/department/hla/extension/extension-publications-library/ext-pubs/ho-237-w.html). University of Saskatchewan (Canadian university guide), Gardening at USask: Cannabis (https://gardening.usask.ca/gardening-advice/sorted-by-plant/cannabis.php).

FAQ

What pH should a hydroponic cannabis reservoir be?

University of Missouri Extension gives 5.5 to 6.5 as the optimum pH for most hydroponic crops, and Purdue Extension’s 5.4 to 6.2 range applies to soilless substrates, not reservoirs. Many growers aim near the middle of Missouri’s range.

How often should I check pH and EC?

Check every few days and log the readings. Calibrate your pH meter weekly with pH 4 and pH 7 buffers, as University of Missouri Extension recommends.

What EC should I use for cannabis in hydro?

Follow your nutrient label. The EC numbers in this guide are example ranges, and University of Missouri Extension notes EC does not confirm the concentration of individual nutrients.

Is a hydroponic schedule different for autoflowers?

Yes. Autoflowers start flowering by age, often around weeks 4 to 5, so their vegetative rows are short. Photoperiod plants flower after you switch to 12 hours of light and 12 of uninterrupted darkness.

Why are my hydroponic roots turning brown?

Warm water and low dissolved oxygen are common causes. University of Missouri Extension notes warmer water holds less oxygen and lists above 6 ppm as optimum.