Mr Pumice Planting pumice

Pumice makes great medium for succulent growing. You can mix pumice with various things (according to availability in your place) to make potting mix. For soil, you'd want clean, sterilized, commercially made soil (cactus soil/medium). If you want to make the mix yourself, you can try mixing soilless materials with compost such as : peat moss, grain husks, burnt husks, dried fern roots, or coco peat. Make sure you don't mix with garden soil, as this might contain pests or disease agents.

Pumice allows good drainage for your pot/planter as well as povide better aeration for roots and allowing the roots to attach themselves to the medium easier. It is preferable to use pumice of size about 3–6 mm for better effects. Here is a brief examples of how much pumice you'd need and what you're going to mix it with :

For small pots with small drainage holes, use half part pumice (50%) and another half (50%) mix of compost and peat/husks. Pots with smaller drainage need more pumice, you can add more pumice to improve the drainage. Some succulents can even thrive with about 80% pumice in the medium. This is preferable to root new or smaller plants.

For larger pots with good drainage, use one third part of pumice (33%) mixed with one third part of compost (33%) and the rest either peat or husks. Burnt materials (husks or peats) tend to stay longer before decomposing into soil than dried ones.

For outdoor beds, use one fourth part of pumice (25%) and another three-fourth (75%) materials like husks or peats. Add compost afterwards accordingly.

Top dressing is used to reduce water splash when watering, discourage weeds, increase the aesthetics, and retain moisture. For top dressing, you can add a thin layer of pumice in the pot/planter. Another alternatives are rock pebbles and crushed gravels. Try to avoid using limestones as this might increase alkalinity.