Hydroponic Nutrient Schedule: Simple Week-by-Week Feeding Chart

A clear hydroponic nutrient schedule is the difference between confused guesswork and consistent harvests. Instead of wondering how much to feed and when, you follow a chart. This guide gives you simple, tested feeding schedules for the three most common beginner crops — lettuce, herbs, and tomatoes — plus everything you need to know about adjusting them for your specific setup.

If you have ever asked “how much nutrient do I add this week?” or “when should I increase the dose?” then a proper hydroponic nutrient schedule answers those questions for you. Print it, stick it next to your growing area, and stop overthinking.

Why do you actually need a hydroponic nutrient schedule?

A nutrient schedule exists because plants do not need the same nutrition throughout their life cycle. A tiny seedling can be killed by full-strength nutrients that would be perfect for a mature plant. A flowering tomato needs more potassium and phosphorus than a leafy lettuce. Without a schedule, beginners typically make one of two mistakes:

• Overfeed seedlings at full concentration, causing nutrient burn and stunted growth
• Underfeed mature plants still using seedling-level concentrations, causing slow growth and yellowing leaves

A simple hydroponic nutrient schedule eliminates both problems by telling you exactly what to do at each stage.

What is the simplest hydroponic nutrient schedule for lettuce?

Lettuce is the easiest crop to schedule because its needs are modest and consistent. Here is the complete week-by-week hydroponic nutrient schedule for growing butter lettuce in a Kratky or DWC system using Formulex (a one-part nutrient).

Week	Stage	Formulex Dose	pH Target
Week 1	Germination (no nutrients yet)	0ml — plain water	N/A
Week 2	Transplant (seedling)	2.5ml per litre	5.8-6.0
Week 3	Establishment	3.5ml per litre	5.8-6.0
Week 4	Active growth	5ml per litre	5.8-6.2
Week 5	Maturation	5ml per litre	5.8-6.2
Week 6	Harvest	No top-up needed	N/A

For Kratky systems, you mix the full nutrient solution once at week 2 and do not add more until starting a new grow. For DWC systems, you replace the entire reservoir every 2 weeks with a fresh batch at the appropriate stage concentration.

What is the best hydroponic nutrient schedule for herbs?

Herbs like basil, mint, and coriander are nearly identical to lettuce in their nutrient needs but tolerate slightly higher concentrations once mature. This basil-focused hydroponic nutrient schedule works for all common kitchen herbs.

Basil and other herbs differ from lettuce in one important way: they continue producing for months after the first harvest. This means your hydroponic nutrient schedule for herbs is open-ended — you keep feeding at the mature plant rate as long as the plant produces.

What is the hydroponic nutrient schedule for tomatoes?

Tomatoes are more demanding than leafy greens because they go through three distinct growth phases: vegetative (leafy growth), flowering, and fruiting. Each phase needs a different nutrient ratio. For tomatoes, a three-part nutrient system like General Hydroponics Flora Series works much better than a single-bottle nutrient.

Stage	FloraGro	FloraMicro	FloraBloom
Seedling	1ml/L	1ml/L	1ml/L
Vegetative	3ml/L	2ml/L	1ml/L
Early flower	2ml/L	2ml/L	3ml/L
Heavy flower/fruit	1ml/L	2ml/L	4ml/L
Ripening	0ml/L	1ml/L	3ml/L

Notice how the ratio shifts from grow-heavy (high FloraGro) during vegetative growth to bloom-heavy (high FloraBloom) during flowering and fruiting. This is the key principle of any hydroponic nutrient schedule for fruiting crops: shift towards more phosphorus and potassium as the plant transitions from leaves to flowers and fruit.

Intermediate level: how to use EC instead of dosage

Once you have run several successful grows using the dosage-based hydroponic nutrient schedule above, you can upgrade to using EC (electrical conductivity) measurements for more precise control. An EC meter (£15-30) measures the actual concentration of dissolved minerals in your water rather than relying on the dosage chart.

Crop	Target EC (mS/cm)	Target PPM
Lettuce	0.8-1.2	560-840
Herbs (basil, mint)	1.0-1.6	700-1120
Tomatoes (vegetative)	1.8-2.5	1260-1750
Tomatoes (fruiting)	2.5-3.5	1750-2450

What next? Refining your nutrient schedule

Once you are comfortable following a basic hydroponic nutrient schedule, here are the natural next steps to improve your results:

• Add a Cal-Mag supplement if growing in soft water areas. £5-10 from any hydroponics shop.
• Track nutrient consumption in a notebook to learn how each crop responds in your specific conditions
• Experiment with bloom additives like PK 13/14 boosters during the heavy fruiting phase of tomatoes and peppers
• Try the Masterblend 2:1:2 dry formula for serious cost savings on larger grows
• Build a custom schedule for unusual crops based on the principles in this guide

Frequently asked questions about hydroponic nutrient schedules

Do I need a different hydroponic nutrient schedule for each crop?

Not necessarily. Most leafy greens (lettuce, spinach, kale, pak choi) and herbs (basil, mint, coriander, parsley) can use the same simple lettuce schedule with excellent results. Only fruiting crops (tomatoes, peppers, strawberries, cucumbers) need a different schedule with bloom-phase adjustments.

How often should I change the nutrient solution?

For DWC systems, replace the entire reservoir every 1-2 weeks. For Kratky systems, you only mix nutrients once at the start of each grow — no replacement needed because the plant uses the entire batch as it grows. Recirculating systems like NFT typically need refreshing every 2-3 weeks.

Can I follow a hydroponic nutrient schedule with tap water?

Yes, in most areas. UK tap water typically works fine for hydroponic growing as long as you adjust pH to 5.5-6.5 after adding nutrients. The exception is very hard water areas with high mineral content (above 200 PPM at the tap), where you may want to use filtered water or RO water for sensitive crops.

What happens if I deviate from the nutrient schedule?

Small deviations are fine — hydroponic nutrient schedules are guidelines, not rigid rules. Going slightly under (using 4ml instead of 5ml) usually causes no problems. Going significantly over (using 10ml instead of 5ml) causes nutrient burn. When in doubt, dose lower rather than higher. You can always add more, but you cannot easily remove excess.

Should I top up nutrients between scheduled changes?

For DWC systems, top up the reservoir with plain pH-adjusted water (no additional nutrients) when the level drops. The plant absorbs water faster than nutrients, so adding pure nutrient solution would gradually concentrate the minerals to dangerous levels. For Kratky systems, never top up at all — let the water level drop naturally.

Why does my nutrient schedule recommend half strength for seedlings?

Young seedlings have small root systems that are easily damaged by concentrated nutrient solutions. Starting at half strength gives the plant time to develop a robust root system before exposing it to full nutrient concentration. After 7-10 days at half strength, the plant is ready to handle stronger nutrients without risk of burn.

How do you adjust a hydroponic nutrient schedule for your specific setup?

The schedules above are starting points, not absolute rules. Several factors might mean you need to tweak your hydroponic nutrient schedule slightly for your specific situation. The good news is that small adjustments are easy and your plants will tell you whether you have the balance right.

What if your water is very soft or filtered?

Soft water and reverse osmosis (RO) water lack the natural calcium and magnesium that hard tap water provides. If you use either, your nutrient schedule needs an additional Cal-Mag supplement at 1-2ml per litre across all stages. Without it, you will see calcium deficiency symptoms (curled new leaves, blossom end rot in fruiting crops) regardless of how perfectly you follow the main schedule.

What if your room is unusually warm or cold?

Warmer rooms (above 24°C) cause plants to drink and feed faster, depleting nutrients more quickly. In warm conditions, refresh your reservoir more frequently — every 7-10 days instead of every 14 days. Cooler rooms (below 18°C) slow nutrient uptake significantly, so plants need less concentrated solutions. Consider reducing dosages by 25% during cold weather growing.

What if your plant looks unhappy despite following the schedule?

The most common cause of unhappy plants on a perfect hydroponic nutrient schedule is pH drift. Even with the right nutrient concentration, plants cannot absorb anything if pH is outside the 5.5-6.5 range. Test pH every 2-3 days and adjust as needed. Schedule problems are rarely the actual cause of issues — pH problems pretending to be schedule problems are extremely common.

Related posts you might find useful

• Hydroponic Nutrients for Beginners — Start here if you are new to mixing nutrients
• Hydroponic Nutrient Deficiency Chart — Identify and fix nutrient problems by leaf symptoms
• Hydroponic Lettuce Week-by-Week Guide — See how the schedule applies to a real grow cycle