Making your own custom-made soil

• A good soil mix should include between 25% and 35% clean concrete sand (medium, coarse).
• Other inert materials such as perlite and vermiculite (found in nurseries and garden shops) can be a part of the other 65% to 75%.
• Clean organic materials can also be used – alone or in combination – such as sawdust, peat moss, and rice hulls, or ground-up pine needles, tree bark, and coconut coir.
• Sawdust from most wood is safe to use, even fresh from the saw. Avoid walnut as it is harmful to tomato and other nightshade plants.
• Do not use wood shavings. They are too coarse, do not hold or provide water and nutrients, and they sometimes turn sour.