Hydroponic Nutrient Schedule Generator | Free Tool
A nutrient schedule is one of those things that sounds complicated until you realize it is just a repeating pattern: feed, check, adjust, repeat. The hard part is knowing what that pattern should look like for your specific plant, system, and growth stage. This generator takes your inputs and builds a week-by-week schedule you can actually follow, so you are not guessing at EC targets or wondering if your seedlings are getting too much too soon.
If you have been eyeballing your nutrients or copying someone else’s schedule and hoping for the best, this tool gives you a baseline tuned to your setup.
How to Use the Nutrient Schedule Generator
- Select your plant type: different crops have different demands. Leafy greens run lower EC than fruiting plants like tomatoes or peppers.
- Choose your hydroponic system: DWC, NFT, Kratky, and flood-and-drain each handle nutrient delivery differently, and reservoir size affects how often you will need to top off or change solution.
- Enter your reservoir size: this determines the quantity of concentrate to mix per change, not just ratios.
- Set your starting week: if you are transplanting established seedlings at week 3, enter 3 so the schedule shows only the weeks ahead of you.
- Review your output: the generator returns a week-by-week table showing target EC, suggested PPM range, nutrient ratios, and notes. Use it as a starting point, then dial in based on how your plants respond.
Frequently Asked Questions
How often do you add nutrients to hydroponics?
It depends on your system and reservoir size, but in most recirculating setups you are topping off with plain water between changes and doing a full nutrient change every 7 to 14 days. In a Kratky or passive system, you add fresh solution when the reservoir drops rather than flushing on a set schedule. For a more detailed breakdown by system type, the guide on how to feed hydroponic plants walks through timing for each setup.
What PPM should my hydroponic nutrient solution be?
Seedlings: 100 to 400 PPM. Vegetative stage: 400 to 800 PPM depending on crop. Fruiting and flowering: 800 to 1,400 PPM for heavy feeders. These are not hard ceilings, but if you are running tomatoes at 1,800 PPM and seeing tip burn, you have gone too far. The General Hydroponics PPM chart gives specific targets by brand and growth stage if you are using GH nutrients.
How do I know when to change my hydroponic nutrients?
Every 7 to 14 days is the standard recommendation, but the real answer is: when your EC drifts out of range or you cannot bring it back to target by topping off. Smell is also a reliable signal, especially in recirculating systems. If the reservoir smells sour or off, change it regardless of schedule. You can read more about the specific signs in the post on when to change hydroponic nutrients.
Do different plants need different nutrient schedules?
Yes. Leafy greens like lettuce and basil want lower EC and higher nitrogen relative to phosphorus and potassium. Fruiting crops flip that ratio during flowering, pulling hard on phosphorus and potassium while nitrogen needs drop. Running a lettuce schedule on your tomatoes during flowering is one of the most common reasons home growers get poor fruit set.
How often should I flush my hydroponic system?
For most systems, a plain water flush every 4 to 6 weeks helps prevent salt buildup in lines, growing media, and net pots. Some growers flush the week before switching from vegetative to flowering to reset the solution before increasing phosphorus. If you are seeing white crust on your hydroton or rapid EC swings between top-offs, flush sooner.
Once you have your schedule, use the hydroponic nutrient calculator to convert your target EC and reservoir size into exact milliliter measurements for each part of your nutrient concentrate. For a complete set of tools to manage every variable in your system, the hydroponic tools collection covers everything in one place.