Filling up empty space may be the most obvious challenge in creating a new garden, but surely the challenge that keeps on giving the gardener headaches is bad soil. Some sites naturally have poor soil for gardening - like super-sandy areas near the Bay, or the potter's dream of pure red clay in some parts of our region. Other spots have human activity to thank for soil that's difficult to plant in - the compaction caused by being walked on over the years or worse, by being driven or parked on, or most commonly, by the use of construction equipment like backhoes. And those backhoes are notorious not just compacting the soil but also for removing all the topsoil and leaving a horrible mix of subsoil, bedrock and construction debris in its place. Some developers even do that deliberately in order to sell off the good topsoil to soil-dealers!
Plan A for Better Soil
So what did I discover beneath the surface of my own new garden? Clay, nothing but, and heavily compacted, too. So my original plan was to hire someone to till the entire property and mix in the requisite amount of compost, which would have created a great start for a new garden. But no dump truck could get close, and the hundreds of bags of compost would have cost a lot, as would the days of manpower required, plus the cost of the tiller - you get the idea. So on to Plan B, a plan that'll take years to implement but hopefully will suffice for growing good-enough plants. (Sounds like gardener's heresy, I know, but this is reality.)
Plan B for Better Soil
I did actually hire someone to remove lots of weeds and misshapen old shrubs, but the rest of the grunt work will be up to me. So here's the plan: to simply amend like crazy around every single plant that goes in the ground. So I dig extra-wide holes, sprinkle in some Espoma Biotone to spur good root growth, and add equal parts Leafgro to the backfill. The last step is getting rid of the discarded bad soil, but miraculously, I've found neighbors who want it.
Just as important is the organic mulch on top of the soil - always a good 2-3 inches. It'll break down over a few months and release some nutrients while improving the soil's texture, which is JUST as important as the amount of nitrogen, phosphorus and potassium in the soil.
Texture refers to the size of the soil particles. With sandy soils, the particles are large and water moves quickly through them. The opposite on the texture scale is clay, which has particles so tiny and packed together that it's hard for water to penetrate and then move through it, and thick clay is also lacking in space for air - or plant roots, for that matter. Ditto making room for the gardener's shovel to make much headway.
The happy medium is called sandy loam, the ideal condition for holding water and air but also leaving room for air, water and roots to move through the soil.
So, how do you change too-clayey soil into just-right sandy loam? NOT by adding sand, which is a recipe for cement. Similarly, the fix for sandy soil isn't to add clay. The fix for both these problems is the same - adding organic matter. Like the Leafgro I dig in while planting, and the organic mulch that breaks down over time and becomes part of the soil. Organic matter in soil allows movement of air, water, nutrients and roots, but also provides some nutrients and just as importantly, allows beneficial microbial activity to take place. Organic matter is truly the Miracle Cure for what ails the soil.