Organic / Soils

Organic soils are the most forgiving way to grow indoors. A good soil already contains nutrition, holds pH steady on its own, and gives you days rather than hours to spot a problem – which is exactly what a first grow needs.

Light-mix or all-mix?

Nearly every brand sells two versions and the difference matters:

• Light-mix is lightly pre-fertilised – enough for one to two weeks. You take over feeding early, which means more control. This is the one to buy for cuttings, seedlings and any grow where you intend to feed.
• All-mix is heavily pre-fertilised – four to six weeks of food built in. Less work, less control, and it will burn young seedlings. Good for established plants going straight into their final pot.

If you are unsure, buy light-mix. Adding nutrition is easy; taking it out is not.

What makes a soil good indoors

• Structure that holds air. Garden compost compacts and drowns roots in a pot. Indoor mixes are built light, usually with perlite or bark already in.
• Biology. Organic nutrition only works if microbes are there to convert it – see beneficials and inoculants.
• Buffered pH. A healthy soil holds itself around 6.0-6.8 without you chasing it with pH down.
• Clean. Bagged indoor soil is heat-treated. Garden soil brings fungus gnats and worse – see fungus gnat control.

Watering soil

The most common way to kill a plant in soil is kindness. Water thoroughly, then wait until the pot is noticeably light before watering again – typically every two to three days. Constantly damp soil has no air in it, roots suffocate, and the symptoms look identical to overfeeding. Adding 20-30% perlite makes this much harder to get wrong.

What we stock

Biobizz Light-Mix and All-Mix, Plant Magic Soil Supreme, Plagron, BioTabs, worm castings and organic amendments. Feed with organic plant nutrients, and compare against coco on the growing media page.

Soil FAQs

Do I need to pH my water for soil?
Much less than in coco or hydro. A living soil buffers itself, and most UK tap water is fine straight out of the tap for organic soil growing.

How big a pot?
Roughly 11L per plant for a normal veg in a 1.2m tent, larger if you veg longer. See pots and saucers.

Can I use garden compost?
Don't. It compacts in a pot, has no air, and brings pests indoors with it.

Why buy soil from The Hydro Bros?

We are a hydroponics shop in Croydon and we stock soil by the pallet for counter sales, so it is fresh rather than dried out. Tell us your setup and we will tell you light-mix or all-mix. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.