In real-estate, the mantra when buying a house is “location, location, location”. When growing a garden and especially growing tomatoes the equivalent advice about gardening is that “it’s the soil, soil, soil”. In San Diego, unless you are extremely fortunate or you live where someone else has amended the soil, lurking under that first few inches of topsoil is the nastiest, hardpan clay that when mixed with the right amount of water is nearly as good as cement. For the untutored, tomatoes do not grow well in cement.
I have been growing tomatoes for a number of years, and when friends and acquaintances find out about my avocation they ask what are the “secrets” for growing good tomatoes. I can talk to them about buying plants or growing from seed, what fertilizers to use, how to spot insect or disease infestation, but in the end, it always comes down to what is the condition of your soil. Sometime this winter, try this experiment. Put on some boots or heavy soled shoes, get some gloves, a shovel and pick a spot in your garden where you would normally plant tomatoes. Dig a trench approximately 6” to 8” across and 18” to 24” deep for a length of about 2’-3’.
Generally, and certainly in 99% of San Diego back yards, you will dig to a depth of 4” to 6” and you will begin to encounter a hard substrate. This is that nasty clay I spoke of earlier. You will find that your shovel does not cut through the clay as it is too dense and hard. At this point you will need a pick axe. I didn’t tell you about the pick axe earlier as I did not want to scare you. A quick note about tomato characteristics is that a fully developed tomato plant will have a root system that will extend 2.5’ to 3.5’ below the tomato plant. Roots will extend in a rough circle approximately 18” to 24” around the plant. Now I have a question for you. If you could not penetrate the soil of your garden below 6” to 8” with a shovel, how do you expect your tomato plant to do so?
The best advice I can give to anyone contemplating growing tomatoes is to enrich and amend your soil to a depth of at least 24” and 36” if possible. I speak from experience when I tell you this is hard, back breaking sweaty work whether you do it yourself or hire someone to amend the soil. The bottom line is that there is no better way to ensure good tomatoes than improving the soil they grow in. In future blog posts, I will provide some tips about amending your garden’s soil. Remember, “it’s the soil, soil, soil”.