Here is the basic crash course in area prep and planting in southern California soils:
Our soil is young and rich; all the minerals it need are there. Some are suppressed because the soil is alkaline, but nitrogen is soluble and always fairly low. You counteract the low nitrogen by adding (mildly) nitrogen rich compost or manures (not really that high in nitrogen, but possibly high in salts as well), or growing ‘green manures’ – nitrogen fixing beans, peas, clover, etc.
You can add agricultural sulfur to the soil before you work it up to slightly change the pH; this is a slow but long term treatment. Other sweetening amendments or mulches include pine needles or peat moss (note: peat moss comes at a an environmental cost – I’m trying to move away from it). Lawn and garden chemical fertilizers also acidify the soil, soil if you are just going organic, your soil is probably good as it is.
Here is the theory: You start off correcting compaction through working amendments into the ground to get the soil particles loose enough to allow air into the soil. You create whatever sort of raised bed you want (they help keep root zones from getting saturated), cover them with mulch and / or compost, and put in the plants. After that, the roots penetrate the soil further loosening it, and the mucilage they secrete binds the soil into clumps giving it what is referred to as ‘structure’. Worms are attracted to the growing areas and the dead roots from previous crops, and as they loop up to the surface and feed on the bottom of the mulch layer, they carry than material back into the deeper part of the soil.
In its extreme form, called ‘permiculture’, you NEVER till the soil – you let the roots, bacteria, fungi and worms do all the work. I work mine up every few plantings, and then only to work in more compost or reshape the beds. As long as you NEVER walk on the beds, especially when they are wet, they will develop a light fluffy consistency all on their own.
Now that you have a good garden soil, transplanting the baby plant from the pots or 6-packs is pretty easy. Garden plants fall into two categories, either potatoes and tomatoes, or everything else. Potatoes and tomatoes grow extra roots from their stems, and can be cover to the bottom of the first leaves (in the case of tomatoes) or progressively up the stems (in the case of potatoes).
All other plants get planted with the soil level of the container at or above the soil line. Do not dig the holes deeper than the root ball. All that does is let the root crown sink below ground level. Put the plant in the hole, scoop the excess dirt in around it and (gently) firm it down around the root ball. Water them well to allow the back-fill to settle into firm contact with the transplant.
Do not add any amendments to the back-fill material. Plant the root balls directly in their new native soil. Amendments in the back-fill just add a layer of insulation that prevents the newly plated roots from getting the moisture in the soil.
For more how-to information, please visit my web site, gardening-coaches.com