How Much Do I Water & Feed My Plants When Growing In Coco Coir?
One of the most common questions in hydroponic growing is:
How much should I water and feed my plants?
The answer depends on several factors, including:
- The hydroponic growing medium
- Pot size
- Plant size
- Environmental conditions
- Plant consumption rates
In this guide we cover one of the most popular hydroponic growing media used in run-to-waste (RTW) systems:
- Coco Coir
- Coco Coir Perlite mixes
This tutorial focuses on hydroponic coco coir feeding techniques and daily nutrient management in RTW hydroponic systems.
Coco Coir Feeding Basics
Coco coir is not soil, so it cannot be treated like soil.
Coco coir should remain moist almost all the time. If coco coir dries out excessively it can inhibit root development and slow root-zone expansion.
This is often confusing for new hydroponic growers, especially those transitioning to coco coir-based hydroponic systems.
Run-To-Waste (RTW) Feeding Explained
For this example we will use a run-to-waste hydroponic feeding method.
Run-to-waste simply means that when feeding nutrient solution, a small amount of run-off exits the pot. This indicates the hydroponic medium has been evenly saturated without becoming waterlogged.
The goal is to keep the root zone oxygenated while supplying consistent hydroponic nutrients.
Everything Is Relative to Pot Size & Plant Growth
Feeding Seedlings in 100mm Pots
100mm pots are commonly used for seedlings during the first 2–3 weeks before transplanting into larger hydroponic pots.
At this stage:
- Plants do not consume large amounts of nutrients
- Plants still require daily feeding
- Root development is the priority
This is where micro-feeding becomes important.
Small daily feeds encourage root-zone development, which improves nutrient transport and increases nutrient uptake as the plant grows.
Coco Coir Feeding Schedule for Seedlings
Step 1 – Seed Germination
- Seed planted
- Seedling emerges
- Transplant into a 100mm pot filled with coco coir
Step 2 – Initial Feed
Prepare:
- 1L water
- 0.5–1ml rooting solution
Gently water approximately:
- 300–400ml nutrient solution
Feed until the coco coir is thoroughly saturated.
Daily Micro-Feeding in Coco Coir
After the initial saturation feed:
- Feed daily
- Use the same nutrient strength
- Apply approximately 50–120ml per feed
This smaller volume should still achieve light run-off similar to the original watering.
The purpose is to maintain moisture in the coco coir while encouraging rapid root development.
Increasing Feed Volume as Plants Grow
At the beginning of each new feeding week:
- Increase nutrient strength slightly
- Continue daily feeding
- Increase solution volume gradually as plant consumption increases
As root mass expands, plants will uptake more hydroponic nutrients and dry the pots faster.
This increase in nutrient consumption is a sign of healthy root-zone development.
Once the root system becomes well established and the plant rapidly consumes nutrients, transplant into a larger pot and repeat the same feeding principles.
The only major difference is the amount of nutrient solution being applied.
Vegetative Stage Coco Coir Feeding
During the vegetative stage:
- Coco coir plants require daily feeding
- Coco coir should never be allowed to remain dry for long periods
Most hydroponic growers using RTW coco coir systems feed:
- 1–2 times daily
- During the 18-hour light cycle
Feed frequency depends entirely on:
- Plant size
- Root mass
- Environment
- Pot size
- Dry-back rate
Monitoring how quickly the plant consumes nutrient solution is one of the most important hydroponic growing skills.
Flowering Stage Coco Coir Feeding
Flowering plants require more interaction and monitoring.
The same rule still applies:
Feed Every Day
In hydroponic coco coir systems, flowering plants commonly require:
- 1–4 feeds per day
The exact number depends on:
- Pot size
- Root-zone size
- Environmental conditions
- Nutrient uptake rates
Early Flower Feeding
During the first 2 weeks of flowering, plants translocate sugars produced during vegetation growth.
At this stage, plants often consume significantly more nutrient solution.
Mid Flower Feeding
Consumption commonly slows for approximately 2 weeks, meaning growers can often reduce feeding frequency to:
- 1–2 feeds daily
Full Flower Feeding
Once plants fully transition into flower, nutrient demand can increase rapidly again for another 2–3 weeks.
During this stage, hydroponic nutrient uptake can become extremely aggressive.
Understanding Plant Consumption
Hydroponic feeding is always influenced by the growing environment.
Every plant is unique, and hydroponic growers must learn to observe:
- Pot weight
- Dry-back speed
- Root-zone health
- Nutrient uptake
- Environmental conditions
Feeding schedules are guides only. Successful hydroponic gardening requires observation, adjustment and consistency.
Summary
Healthy hydroponic coco coir growing comes down to balancing:
- Moisture
- Oxygen
- Nutrient availability
- Root-zone health
Understanding how quickly your plants consume nutrient solution will help you determine the ideal hydroponic feeding frequency for your system.
*This tutorial serves as a guide. Closely monitor your plants and adjust feeding frequency as necessary.
