Plant Soil Guide — Which Potting Mix Should You Use?

Using the wrong soil type causes problems no amount of careful watering can fix. Here's a guide to soil components and the right mix for every plant type.

Soil is not just an anchor for roots — it determines how water drains, how much air reaches the roots, and what nutrients are available. Getting the mix wrong creates problems that are difficult to diagnose and slow to fix.

Key Soil Components and Their Roles

• Potting mix — the base for most houseplants; contains nutrients and organic matter.
• Perlite — white volcanic granules; improves drainage and aeration; prevents compaction.
• Vermiculite — retains moisture; used in seed-starting mixes.
• Peat moss — acidic; retains moisture well; ideal for acid-loving plants.
• Coco coir — sustainable alternative to peat moss; excellent moisture retention.
• Coarse sand — improves drainage; used in succulent and cactus mixes.

Recommended Mixes by Plant Type

• General houseplants — 70% potting mix + 30% perlite.
• Succulents/cacti — 50% potting mix + 30% perlite + 20% coarse sand.
• Orchids — specialist orchid bark mix (not standard potting soil).
• Ferns/Calathea — 60% potting mix + 20% coco coir + 20% perlite.
• Seed starting — 50% vermiculite + 50% coco coir (no nutrients needed yet).

Replace Old Soil

Potting mix breaks down over 1–2 years — it compacts, loses structure, and becomes depleted of nutrients. Always use fresh soil when repotting. Reusing old soil from a plant that died is particularly risky.

Adding just 20–30% perlite to standard potting mix significantly reduces the risk of root rot from overwatering — one of the simplest improvements you can make.