Ratios Of Soil

Question

So, I am wanting to do a raised garden bed this year. The dimensions of the bed are 6ft. x 8ft x 33.5 inches (I imagine I might only go to 28 inches to leave some room at the top). Which comes to a little over 4 cubic yards of soil that is needed. I am trying to figure out the best soil to buy. I’ve read that a good ratio is 1/4 garden soil, 1/4 compost material, 1/4 peat moss, and 1/4 vermiculite or perlite. A couple of questions. 1. Should I do 1/8 vermiculite and 1/8 perlite? 2. I read that perlite expands up to 20 times its size, so would I need an entire cubic yard of perlite, or will it expand and I really can get less? 3. If my options are a cubic yard of leaf compost or a cubic yard of mushroom compost, which would be more preferable (trying to buy in bull to save money) 4. Any other suggestions you may have?

Answer 1

Other than most standard raised bed mixes, I only have two small preference differences.

1. I prefer vermiculite over Perlite, but Perlite is much cheaper in bulk. Either will work just fine.

2. Mushroom compost is a good mix that skips a step in composting. It is already in a form that plants can use, and if there are any surviving spores or mycelium they can help clean and break down the soil further. I produce my own mushroom compost and use it as often as I need to. It is a superb amendment.

Make sure to mix well, and it is best to let it sit for a few weeks before planting. If you can't wait, it will be fine. It is just best to let the mixed soil sit for a bit.

Here are some articles that will help:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/mushroom-compost.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/best-soil-raised-garden-beds.htm

https://www.gardeningknowhow.com/special/organic/the-importance-of-soil-for-an-organic-garden.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/improving-garden-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/compost-as-soil-amendment.htm