The first step in winterizing a lawn or garden is to not be enticed by seductive marketing.
Advertising schemes in the gardening industry use terms such as "turf builder" and "winter guard," or positioning phrases like "fertilize in fall for healthy trees and lawn in spring." The lie hidden in all of those terms is based in each person's subconscious susceptibility to want something but not necessarily need something. Our susceptibility is enabled by the long-standing societal norm of accepting any company's product claim as being true as the gospel. The turf industry has done considerable research into fertilizer composition and application technology over the past half-century. However, most of the turf research has been done by universities where the research is funded by fertilizer manufacturers, the turf maintenance industry or Big-Ag. A rather self-serving arrangement for bedfellows whom regularly work together under the guise of research, but it's really product development. Fertilizer and plant research has revealed that some, but not all, of the fertilizer applied in the fall will be metabolized and stored in plant roots for use by the plant in the following spring. The science has been exploited for profit at the expense of our environment and your wallet.
There are some serious environmental consequences of fall fertilization of lawn or garden plants, especially in our Pacific Northwest climate. Firstly, we live in a region that receives high rainfall in the autumn, which leads to fertilizer runoff into rivers, lakes, drinking water aquifers and the ocean. The end result of fertilizer runoff into marine environments is oxygen deprivation for fish, ammonium toxicity to all marine life and marine dead zones. Anywhere fertilizer from farms or gardens runs off land into the ocean, aquatic dead zones occur. For example, off the coast of Oregon, in the Sea of Cortez in Mexico and parts of the Great Lakes.
Secondly, and beyond the death of marine life, which few people seem to care about, there is the issue of paying one dollar, as an example, for fertilizer but only receiving 50 cents of real value. The other 50 cents is lost to leaching, runoff and nutrient-ion antagonisms. You get half value and Big-Ag gets all the profit.
There is also the issue of the soil's pH control of nutrient uptake. Soil pH controls all availability of nutrients, whether the nutrients are applied or pre-existing. If the soil pH is too low (common in our region) nutrient availability will be limited for uptake. Liming to raise the soil's pH to make nutrients more available cannot be done simultaneously with fertilizer application or lime-induced chlorosis will occur. And since few homeowners test their soil's pH to understand soil chemistry, applying fertilizer without knowing the pH level is nothing more than a shot in the dark and a waste of money.
I often read bloggers, Big-Ag marketers and garden writers who have absolutely no real horticulture training or experience in the field, promoting fall fertilization to keep lawns and gardens healthy. I have never seen or heard of a single employee from a fertilizer manufacturer, garden centre or home and garden store visit a residential garden to determine soil type, pH or crop type to accurately specify type and amount of fertilizer. So how could they ever know what your plants or soil actually need? Scattering 0-20-0 super phosphate or ammonium sulfate 20-0-0 around any plant without a purpose or verified nutritional status is vanity-induced capitalism, not horticulture. Diagnosing pre-existing soil fertility while determining the crop's actual nutritional needs is a fundamental requirement of professional crop growing. The only way to know those factors is to have a soil test and a foliar analysis done to determine nutrient levels in soil and plant. Big-Ag is selling to your desires and wants - intelligence is not required and not preferred.
If you really want to care for your lawn in the fall, use a mulching mower and leave the grass clippings on the lawn so the nitrogen and other nutrients in the grass blade can be metabolized into food by soil organisms. Aerate lawns with poor drainage and don't dethatch in the fall unless your lawn's a sponge. Some thatch is healthy. Test the lawn's pH and only if needed, apply a prescribed amount of lime.
For the garden, don't clean and rake off all of the fallen leaves and other plant debris. Leave such biomass in place to be eaten by worms and other soil organisms that will turn it into food for plants. If fallen leaves bother your sense of aesthetics, which I can appreciate, then apply a layer of mulch over top of the leaves. Most importantly, don't be seduced by marketing, resist the urge to feed your vanity and act with informed purpose.
Todd Major is a journeyman horticulturist, garden designer and builder, teacher and organic advocate. [email protected]
