The soil mix should just feel damp to the touch.

It may simply need to be repotted in a fresh soil mix with more generous space.

Fresh soil mix in a clean pot every year helps.

So extra sand can be added to their soil mix.

The soil mix can be used again and again for years.

This creates air channels and allows the soil mix to breathe.

These plants also need careful planting in a wide deep hole, which has been improved with a good soil mix.

The soil mix should be rather light and well drained.

Fill the box about two-third full with your chosen soil mix.

And as for the soil mix, the sandier the better.