All soil isn’t created equal.
Soil is the first and perhaps most critical part of creating and sustaining a healthy and bountiful garden. It’s much more than just the base that anchors plants to the ground; it’s a complex mix of physical, biological, and nutritive components that must be properly prepared and cared for not just once, but year after year—or you’ll soon find your garden suited for only growing weeds.
On the flip side, well-structured soil with plenty of organic matter is one of your best allies against weather, bugs, and disease. The ideal blend contains the proper balance of nutrients, organic matter, air, water, pH, and more for the plants you’re growing.
But first, you need to determine what type of soil you have.
Sift Out the Truth
There are three types of soil: sand, silt, and clay. Grab a handful and rub it between your fingers to find out what you have.Sand has the largest particles, clay the smallest. Sandy soil is coarse, gritty, and falls apart easily; it also drains well, usually too well, losing moisture and nutrients quickly. Silty soil feels like silky flour when it runs through your fingers—you can form it into mud balls when wet.
Both of these soils will benefit from the addition of compost, peat moss, and aged cow manure. You can make your own or buy it in bags at a garden supply store. At the end of the season, top the garden with shredded leaves (run the lawnmower over them to mulch them), and turn the dried plants under to return their nutrients to the soil.
Clay soil is a unique situation; it’s sticky to the touch when wet, and it holds water—usually too well, leading to “wet feet,” root rot, and diseases. You can easily spot it, as it gets cracks when it dries out. Clay soil tends to be lifeless, and therefore needs a good amount of compost—organic matter already broken down by bacteria and perhaps worms (“vermicomposting”)—to create a biodiverse ecosystem.
It will also benefit from the addition of peat moss, shredded leaves, and, in particular, gypsum. Gypsum adds nutrients and makes the tiny clay particles clump together more so they form into larger particles like loose sand. This in turn improves gypsum’s structure, reduces compaction, and enhances drainage.
Loam is the ideal, balanced combination of sand, silt, clay, and organic matter. But even it will benefit from regular toppings with leaves, straw, and grass clipping if you have them. You’ll want to cover bare soil with some sort of mulch, if only to improve water retention and reduce the need for watering, particularly during dry spells.
All-Important Soil Tests
Sometimes, despite our best efforts, leaves turn yellow, fruits and vegetables are undersized, or other unplanned things occur. A soil test helps head off problems before they happen, and there are four tests you can easily do yourself.First, take a handful of your newly amended soil and squeeze it. Does it form a ball when pressure is applied? If so, that’s good; if not, more of the above-recommended amendments should be added depending on your soil type.
The second test is to dig a six-inch hole and fill it with water. Allow it to drain and then fill it again. If it drains very quickly, the soil is too sandy/silty. If it takes more than 4 hours to drain, the clay needs more amendments.
For the next test, you want the temperature to be warmer than 55 degrees F. Dig out a 12-inch square section of soil, making it one foot deep. Sift through it and count the earthworms. Ten or more is a good sign; worms are a great indicator of biodiverse, active soil. If not, add more organic matter.
The other cause of a lack of earthworms may be soil that is too acidic or alkaline. A home pH test (our fourth easy test), will provide the answer. There are two options: a testing meter or a kit with vials.
With a testing meter, you simply insert the probes into the soil and read the results. This is useful if you need to check many individual planters in a container garden or want to check the soil repeatedly throughout the season.
For the vial method, dig five holes six inches deep, take a soil sample from each, mix them together, and then allow them to dry. The soil must be dry or it can skew the results. A typical vial kit contains around 40 tests.
More advanced kits, which are still relatively affordable, will test for the all-important nutrients nitrogen, phosphorus, and potash (aka potassium), as well as pH. These are great at the start of the season, allowing you to tailor the soil in each area to the plant’s specific needs, and are very helpful when you’re getting lackluster results without an obvious cause.
Don’t worry if you can’t diagnose the problem yourself. Reach out to the nearest university’s cooperative extension; they should be happy to help.
