“I have some large compost bins, which produce a lot of compost. Can I plant things in pure compost, or do I need some “dirt” with inorganic materials for the best results? How much inorganic material do I need?” Question from Naomi or Oakdale, California
Answer: Congratulations on your composting success! Compost is one of the best garden amendments available. You can plant in straight compost, but I suggest incorporating it into your sandy garden soil or mixing it with other additives if you want to use it for container plantings.
Compost as a Garden Amendment
When using compost to fortify gardens, incorporate it evenly into your natural soil. Add it liberally if your soil is of very poor quality–especially if you want to grow crops that need fertile soil, like fruits and vegetables. You might also consider building raised beds to make the most of your compost bounty.
Compost as a Potting Mix Additive
If you plan to use your compost for container plantings, include other additives to encourage better root growth in the long term. These include Black Gold Canadian Sphagnum Peat Moss, perlite, and vermiculite. The peat moss with lighten the mix and give it more structure and porosity, while the perlite will help increase drainage. Vermiculite holds water, adds porosity, and holds and distributes nutrients. A well-rounded potting mix would include 40% compost, 30% peat moss, 20% perlite, and 10% vermiculite.
I hope that this helps, and keep composting!
Black Gold Horticulturist