Adult Soil Mix and Seedling Mix Amendment

This is my basic soil mix. It’s a bit like cooking- nothing is exact. A little of this and a bit of that.

1 bag- Fox Farm Ocean Forest Potting Soil

Other potting mixes will work but this particular brand is formulated with organic, slow release nutrients and buffering agents that are optimal. It is recommended that this mix be screened through 1/4 inch mesh hardware cloth.

To this mix, add pumice at approximately 1/3 of total volume. This provides drainage and proper soil structure preferred by cacti. Perlite may be substituted for pumice but its lighter weight makes it the mix less stable so it is not preferred.

3 cups of powdered gypsum and/or agricultural lime (not hydrated lime). This is important for proper mineral and nutrient absorption.

Approximately 4 cups of washed sand may be added to total which helps with soil structure, but this is optional.

When making soil mix for adult plants (not for seedlings) a low NPK organic powdered fertilizer (1-1-1 up to 4-4-4 NPK ratios) can be lightly mixed in.

When making a mix specifically for seedlings, it is preferred to add fine screened vermiculite at approximately 20% of volume. The size of vermiculite should resemble gritty sand, not the common larger particle type commonly available at garden centers, although small bags of fine vermiculite are often available at Lowe’s or Home Depot.