BioTabs Feed Chart – Organic Grow Guide Doses
BioTabs' own published Organic Grow Guide schedule. Tablets and powders at potting, then single feeds week by week, each in the unit BioTabs use.
- Liquidsper litre of water
- BioTabs1 to 5 tablets per pot
- pH and ECnothing to adjust
Each row carries its own unit. BioTabs tablets are counted per pot. Startrex is grams mixed through the potting soil. Mycotrex is grams sprinkled into the planting hole. Bactrex, Orgatrex, Bio PK 5-8 and Boom Boom Spray are dissolved in water, per litre.
Getting it right
- Start with the right soil. BioTabs ask for a bio light-mix or a lightly fertilised organic potting soil. Not an all-mix.
- The pregrow pot is optional. If you use one, mix 5g of Startrex into each litre of soil, sprinkle 1g of Mycotrex into the planting hole and plant. Give the first watering only with 0.5g of Bactrex and 5ml of Orgatrex in a litre of water.
- The final pot is where the tablets go. Mix 50g of Startrex into every 10 litres of soil, sprinkle 5g of Mycotrex into the planting hole, plant, then press the BioTabs 10cm deep. First watering only: 1 litre of water with 1g of Bactrex and 10ml of Orgatrex.
- Tablets by pot size. 1 tablet for a 5-litre pot, 2 for 10–15 litres, 3 for 20–25 litres, 4 for 30–35 litres and 5 for 50 litres.
- No scales? BioTabs count four tablespoons as 50g and one teaspoon as 5g.
- Flower 3 is the one mid-season feed. 1g of Bactrex and 20ml of Orgatrex in 1 litre of water, given to each plant once that week.
- Bio PK 5-8 goes in three times. 10ml in 1 litre of water per plant, once in Flower 2, once in Flower 4 and once in Flower 6.
- Boom Boom Spray goes on the leaves. 5ml per litre, sprayed until the leaves drip, at the pregrow pot, the final pot and Grow 1. Use the mix within 6 hours.
- A dash means water only. Between the feeds on the chart, water when the plant needs it. BioTabs ask for dechlorinated water.
- Long veg? If your vegetative stage runs past two weeks, press one extra tablet 10cm into the soil in the third week of veg.
- Using AutoPots? Put the tablets 10cm from the bottom of the pot, then fill with soil from the top and make your planting hole.
Everything on the chart
BioTabs tablets
From £14.49
1–5 per pot, final pot
BioTabs Mycotrex
From £35.85
1g pregrow, 5g final pot
BioTabs Bactrex
From £25.95
0.5–1g at potting, 1g at Flower 3
BioTabs Orgatrex
£71.45
5–10ml at potting, 20ml at Flower 3
BioTabs Bio PK 5-8
£149.05
10ml, Flower 2, 4 and 6
Boom Boom Spray
From £19.95
5ml leaf spray, potting to Grow 1
Common questions
Do I need to check pH or EC?
BioTabs say there is no need to adjust pH or EC when you feed with their tablets. Use dechlorinated water throughout, as BioTabs ask.
Is Startrex sold here?
Not at the moment, so there is no card for it below.
Where is PK Booster Compost Tea?
It is not on this chart. BioTabs' 2026 grow guide uses Bio PK 5-8 at Flower 2, 4 and 6. PK Booster has its own manual from BioTabs.
Can I use this in coco or hydro?
This guide is written for organic potting soil, and BioTabs give no coco or hydro doses on it.
Why does the chart restart at 1 for flowering?
Growers count flowering from the switch to 12 hours of light. BioTabs' two veg weeks are Grow 1 and Grow 2, and their nine flowering weeks are Flower 1 to Flower 9.
Figures as published by BioTabs in their Organic Grow Guide, version 2026.01, biotabs.nl. Always read the label on the bottle you own. BioTabs is a trade mark of its owner.