Feeding in Coco: Nutrients, EC & pH Made Simple

July 9, 2026

Coco coir is the best of both worlds — hydroponic speed with soil-like forgiveness. But it comes with three non-negotiables: coco-specific nutrients, CalMag, and pH 5.8–6.2. Get those right and it's honestly hard to fail. Here's the whole system on one page.

The 3 rules EC & pH targets Feed schedule Pick your base Run-off

The three rules of coco

Coco has zero food in it

Unlike soil, coco is an inert sponge — the plant eats ONLY what you pour in. That means every watering is a feed with a coco-specific base nutrient, from the first week to the flush.

CalMag with every feed

Coco fibre chemically holds back calcium and magnesium. Supplement it — every feed, not just when you see rusty spots (by then you've lost two weeks of growth).

pH 5.8–6.2, checked every time

Mix your feed, THEN pH it. Ten seconds with a pH pen is the difference between nutrients that get absorbed and nutrients that sit locked out in the pot.

Your EC and pH targets at a glance

EC (electrical conductivity) is just feed strength — your pen reads how much nutrient is in the water. The ramp looks like this:

No EC pen yet?

You can follow the bottle's ml-per-litre chart instead — start at half the recommended dose and work up. But a pH pen is not optional in coco. If you buy one meter, buy that one.

The week-by-week schedule

Stage	What to feed	Target EC	Notes
Week 1–2 · Seedling	Base A+B at ¼ strength + root stimulator	0.8–1.0	Light feeds, keep coco moist not soaked
Week 3–5 · Veg	Base A+B full veg dose + CalMag + silicon	1.2–1.6	Feed daily once roots fill the pot; 10–20% run-off
Week 6–7 · Early flower	Switch to bloom base + PK starts low	1.6–1.8	Add enzyme weekly from here
Week 8–10 · Peak flower	Bloom base + PK booster + CalMag	1.8–2.2	Watch tips for burn — back off 0.2 if scorched
Final 7–10 days · Flush	Plain pH'd water only	0.0–0.4	Improves final quality; coco drains fast so it's quick

This schedule works with any of the base ranges below — just swap the veg/bloom bottles at the flower flip and keep CalMag constant throughout.

Pick your base range (and stick with it)

Canna Coco A&B

from £14.95

The industry-standard coco base

Shogun Samurai Coco A&B

from £49.95

Multi-award-winning, SmartZen yield tech

Monkey Grow A+B

from £20.00

Coco-friendly two-part veg base

Monkey Bloom A+B

from £20.00

Flower-stage partner to Grow A+B

Then the supporting cast — the difference between an okay grow and a great one:

Shogun CalMag

from £7.95

Insurance policy for coco — use every feed

Canna Rhizotonic

from £11.95

Root stimulator for weeks 1–3

Canna Cannazym

from £7.45

Enzymes — keeps the root zone clean

Shogun Sumo Boost

from £11.95

Our favourite flowering booster

pH Down

£4.95

Hobby pH Pen

£19.95

You cannot grow in coco without one

Shop All Base Feeds

Run-off: coco's self-cleaning trick

Always feed until 10–20% of the volume drains out the bottom. That run-off flushes out the salt residue each feed leaves behind — skip it and salts accumulate until the EC in the pot is far above what you're mixing, and plants stall. Fabric pots on saucers make this easy: feed, let it drain, empty the saucers. If plants look overfed (dark, clawed tips), a plain-water rinse day resets the pot and you're back on track in 48 hours.

Starting from scratch?

The Canna Coco Starter Kit bundles the A&B base with the key additives in one box — pair it with Canna Coco Professional Plus 50L and a pH pen and you're fully equipped.

Quick answers

Which base nutrient should I use for coco?

Any two-part coco-specific base: Canna Coco A&B is the industry standard and almost impossible to get wrong; Shogun Samurai Coco A&B adds their SmartZen yield technology; Monkey Grow/Bloom A+B is a superb value UK-made option. Pick one line and stay with it — don't mix brands mid-grow.

Do I really need CalMag in coco?

Almost always yes. Coco fibre naturally grabs calcium and magnesium from your feed before the plant gets them. A dose of CalMag with every feed (especially with soft or RO water, or under LED) prevents the classic rusty leaf spots and slow growth.

What pH should my feed be in coco?

5.8–6.2, every single feed. Mix nutrients first, then adjust with pH Down (tap water in the UK usually starts around 7–7.5). Outside that window, nutrients lock out even though they're in the pot — most 'deficiencies' are really pH problems.

How often should I water coco?

Treat coco like hydroponics, not soil: little and often, always with feed, never letting it fully dry out. Small plants might need feeding every 2–3 days; by peak flower it's daily. Aim for 10–20% run-off out the bottom each time to stop salts building up.

Can I use soil nutrients in coco?

Not ideally. Coco-specific bases are formulated for coco's calcium/magnesium behaviour and its pH range. Soil ranges under-supply calcium in coco and you'll chase deficiencies all grow.