# Should I feed every time I water?

> Whether to feed every watering depends on the medium. In coco, rockwool and hydro, yes: every irrigation carries nutrient solution at stage strength, about EC 1.2-1.8 mS/cm in veg and 1.6-2.2 in flower. In bagged soil, feed every second or third watering at EC 0.8-1.6 once the starter charge runs out. In living soil, water only and top-dress. Runoff EC tells you if the rhythm is right.

- Canonical: https://genetixbay.com/knowledge/answers/feed-every-watering.html
- Topic: Nutrients · Type: How-to
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Full article: [Building a cannabis feed by stage: ppm targets per element and how to hit them](https://genetixbay.com/knowledge/nutrients/feed-by-stage.md)
- Also asked as: Should I do feed, water, feed? | Do I add nutrients every watering? | Feed then plain water: is that right? | How often should I give nutrients in soil? | Do I feed every watering in coco?
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Short answer

It depends on the medium. In [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md), [rockwool](https://genetixbay.com/knowledge/glossary/rockwool.md) and hydro, feed every irrigation at stage strength. In [bagged soil](https://genetixbay.com/knowledge/glossary/potting-mix.md), feed every second or third watering at [EC](https://genetixbay.com/knowledge/glossary/ec.md) 0.8–1.6 [mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md) once the mix's own charge runs out. In [living soil](https://genetixbay.com/knowledge/glossary/living-soil.md), water only and feed the soil by [top-dressing](https://genetixbay.com/knowledge/glossary/top-dressing.md). *Grower practice*, built on how each medium holds nutrients.

## Why

Inert media hold almost no plant food, so the solution you pour in is the [root zone](https://genetixbay.com/knowledge/glossary/root-zone.md)'s entire supply [1]. Plain-water irrigations in coco or rockwool dilute it, then the next feed spikes it again.

Potting soil is different. Peat, compost and the starter fertiliser hold nutrients on exchange sites and buffer what you add, so a feed every second or third watering keeps up without stacking salts.

More is not better. In deep-flow hydro, doubling [feed strength](https://genetixbay.com/knowledge/glossary/input-ec.md) from 2 to 4 mS/cm raised solution nutrients but not yield or quality [2]. The aim is steady supply, not maximum strength.

[Runoff](https://genetixbay.com/knowledge/glossary/runoff.md) or [pour-through](https://genetixbay.com/knowledge/glossary/pour-through.md) EC is the check: it shows whether salts are building up or running short [3].

## The numbers

| Medium | Feed how often | Feed EC (mS/cm) |
|---|---|---|
| Coco, rockwool, drip | Every irrigation | 1.2–1.8 veg, 1.6–2.2 flower |
| [DWC](https://genetixbay.com/knowledge/glossary/dwc.md), [RDWC](https://genetixbay.com/knowledge/glossary/rdwc.md), [NFT](https://genetixbay.com/knowledge/glossary/nft.md) | Constant (reservoir) | Same ranges |
| Bagged soil | Every 2nd–3rd watering, after weeks 2–4 | 0.8–1.6 |
| Living soil | Never; water only | n/a (top-dress) |

## What to do

1. Identify your medium and pick the rhythm above.
2. Measure feed EC including your water.
3. Check runoff EC weekly in coco and monthly in soil.
4. Runoff more than ~0.8–1.0 mS/cm above input and rising: feed weaker or less often.
5. Runoff well below input: the plant wants more; raise strength slightly.

## Common mistakes

- Plain-water irrigations in coco.
- Hydro-strength feeds every watering in fertilised soil.
- Feeding a [seedling](https://genetixbay.com/knowledge/glossary/seedling.md) in fresh potting mix that already holds 2–4 weeks of food.
- Never measuring runoff, so [salt build-up](https://genetixbay.com/knowledge/glossary/salt-build-up.md) goes unseen.

## Related

- Full article: [Building a cannabis feed by stage](https://genetixbay.com/knowledge/nutrients/feed-by-stage.md)
- Answers: [full-strength feeding chart?](https://genetixbay.com/knowledge/answers/full-strength-feeding-chart.md) · [when soil runs out](https://genetixbay.com/knowledge/answers/when-does-soil-run-out-of-nutrients.md) · [how often to water](https://genetixbay.com/knowledge/answers/how-often-to-water.md)
- Articles: [runoff testing](https://genetixbay.com/knowledge/ph-ec/runoff-testing.md) · [coco](https://genetixbay.com/knowledge/systems/coco.md) · [soil](https://genetixbay.com/knowledge/systems/soil.md)
- Terms: [runoff EC](https://genetixbay.com/knowledge/glossary/runoff-ec.md) · [feed chart](https://genetixbay.com/knowledge/glossary/feed-chart.md)

## Follow-up questions

**Should I feed every watering in coco?** Yes, feed every watering in coco. Coco holds little usable nutrition, so plain-water irrigations starve the plant and swing root-zone EC and pH. Feed at stage strength, about EC 1.2-1.8 mS/cm in veg and 1.6-2.2 in flower, to 10-30% runoff each time. If runoff EC climbs well above input, lower feed EC slightly rather than skipping feeds.

**Is feed, water, feed right for soil?** Feed, water, feed is a sound soil rhythm once the potting mix's starter charge has run out, usually after 2-4 weeks. Feed at about EC 0.8-1.6 mS/cm every second or third watering and give plain pH-adjusted water in between. Check runoff EC monthly: if it keeps rising, feed less often or at lower strength.

**Can I just use a weaker feed every watering in soil?** Yes, a weaker feed every watering in soil works as well as feed, water, feed, as long as the total delivered is similar. Many growers run about half their normal soil strength each time. The rule is the same either way: watch runoff EC, and back off if it climbs more than about 0.8-1.0 mS/cm above what you pour in.

## Sources

1. Sonneveld C, Voogt W, 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6
2. Hershkowitz JA, Westmoreland FM, Bugbee B, 2025. Elevated root-zone P and nutrient concentration do not increase yield or cannabinoids in medical cannabis. Frontiers in Plant Science 16:1433985. https://doi.org/10.3389/fpls.2025.1433985
3. NC State University / NC Department of Agriculture and Consumer Services. The pour-through extraction procedure: a nutrient management tool for nursery crops. https://ncagr.gov/ncsu-pour-through-extraction-procedure/download