A question of note that came up in the August 14, 2021 edition of the Talkin’ Dirt (webcast?) was:
What type of media do I use in my raised vegetable bed?
The easy answer is dirt. The second easy answer is potting soil. Both are right and both are wrong. The best answer is a combination of both, with amendments for nutrition and structure mixed in, and then we call it soil. But, we don’t recommend you go out and buy either and start mixing them. Soil scientists have taken the guesswork out of you having to mix your own raised bed media. They have both bagged this and sell it wholesale at many different nurseries and garden materials stores.
The reason that good quality soil (or media) is so important is that it is the basis for healthy plants. If your soil is not healthy, your plants will not be either. Good quality healthy soil provides access to nutrients, water, and air. It is neither super fluffy nor as hard as a brick. It supports and stabilizes the roots and it helps build natural resistance to pests and diseases.
Questions you have to ask yourself are:
1) How much do I need? - enough to fill up the box (container) but still have 3-4 inches of space so there is no run-off of water and soil. For some people this will be a few bags, for others, this might be a cubic yard or two. The nursery/garden materials store you go to will be able to help you figure out exactly how much you need. You can then take it home or schedule it to be delivered. You can also figure out how much you need by using a soil calculator.
2) Do I want to go organic? - we will always recommend this. It does not mean all of your future gardening must be organic but it is always best to start with top quality most nutritious soil media possible!
3) What is my media going to contain? - The media you pick should be loose and well-draining and have a combination of multiple things, often referred to as amendments. It should have good water penetration / good nutrition / good aeration and can consist of many different components: screened topsoil (loam), pumice stone or lava rock, compost, fir bark, coconut coir, or worm castings.
Feel free to ask questions of the people who are helping you and don’t take “I’m not sure” for an answer. Ask to speak to a supervisor or a manager if you don’t feel your questions are being answered. It is their job and their specialty to provide the best media for your vegetables to grow in and they want you to be pleased.
For an example of what a good organic vegetable blend would contain that you can find in the Bay area, you can look at this website: Lyngso Organic Vegetable Blend