Question
Good Friday Morning Mike:
My grandson, DAVIDE, wants his own veggie garden. Size of are:
11.5 ft. x 12.5 ft. I want to pile about 12 inches of triple mix soil + compost on top of a clayish foundation.
1st ?:
Is 12 inch depth of new soil OK for the first year of growing veggies? How many inches deep would you recommend?
2nd ?:
Would you add any other topsoils to the triplemix + compost?
And what percentages of each type of soil would you recommend, please.
Thank you.
Juro

Answer
Juro, it is far from an exact science. As long as you have an equal mix of organic materials such as shredded leaves, aged manure, peat, and compost, the plants will thrive.

In regard to depth, my raised beds vary between 8" and 12" high. When growing root crops such as carrots and beets, the deeper the better. But a minimum of 8" is ideal for most plants.

I always recommend framing a raised bed.  You can use treated lumber or a non-rotting natural wood such as cedar. Either of these woods will last up to 20 years.

If you choose to use treated lumber, make sure to ask for wood treated with ACQ.  This wood is treated with borax preservatives.  Borax is non-toxic to humans and will not adversely affect your plants, even in the first year.  Recent studies have shown that it is best to stay away from wood treated with arsenic (CCA Wolmanized) or woods treated with creosote.  The chemicals can leach into your soil and have ill effects on both you and your plants.

The down side to using unframed raised beds is that the sides constantly need to be raked in after a hard rain.  If left untended, the plants on the sides can eventually wash away.  The decision is certainly yours.  But my recommendation is to take the time and build the structures.  Over the long term, you抣l be happy you did.

Good luck, and have a great weekend.

Regards,

Mike