For 60 years, chemical companies have encouraged Americans to “weed and feed” their lawns every spring and fall. We bought it hook, line, and sinker, believing that more chemicals equaled a greener, healthier lawn.
As a result of this indiscriminate use of fertilizers and pesticides, we have an overabundance of nitrogen and phosphorous in our waterways, and soil which can’t support the grass growing in it without the help of more chemicals. Many lawns have basically become a chemical dump.
In the wild, grass does just fine on its own
Grasses are of course plants like any other. In the wild, where grasses have thrived for millennia, they’re supported by decomposing organic matter at the soil line, which eventually becomes humus, the nutrient-dense material which supports all plant life. The decomposition cycle is dependent on the many microorganisms and other creatures which live at or just below the soil line, referred to as the soil food web.
This natural cycle can be easily replicated in the suburban landscape, because there’s no shortage of organic material. In fact, the grass itself is the best source. A lawnmower with a mulching blade shreds grass clippings into tiny particles which drop down to the soil line. There, the soil food web breaks them down into their component nutrients – primarily nitrogen, the same chemical provided in huge quantities by commercial fertilizers. The shredded grass clippings are the perfect food, as they break down slowly all season, providing a consistent source of nutrients for your lawn.
The mulched grass clippings also insulate the soil, which increases water retention, and regulates soil temperature. This insulation helps roots grow deeper.
When too much synthetic nitrogen is applied, the grass grows too quickly, resulting in lots of vegetative growth and little root development, which makes the lawn very susceptible to drought and pests. Deep roots are the key to a healthy lawn, not top growth. Grass with shallow roots give up the ghost quickly during a drought or heat extremes.
The truth about lawn thatch
Contrary to popular belief, mulched grass clippings do not create thatch – overuse of chemicals does. When a lawn is bathed in chemicals, the pH of the soil drops, and it develops a high salt content. Bacteria and other organisms which make up the soil food web can’t survive the acidic, salty soil, and either die off, or retreat below to where the soil pH is normal. In a healthy organic lawn, these organisms live at the soil line and break down whatever organic matter is present, including grass clippings, inc. When they retreat, that decomposition does not happen, and thatch forms.
How to properly feed your lawn
If you live in the mid-Atlantic or northern U.S., you have cool season grasses in your lawn (or at least you should), like fescue, ryegrass, Kentucky bluegrass, Timothy, or canarygrass. Cool season lawns should only be seeded in fall. If seeded in spring, sufficient time does not exist for the perennial seeds in the mix to germinate and establish before summer heat sets in. The grass that pops up right away are annual varieties which will die in the heat or at first frost.They’re included in the seed mix to protect and shade the soil while the perennial seeds take their time germinating.
At maximum, cool season grasses should only be fed once in early spring and once in fall. In spring, the time for feeding is when your local forsythias are blooming. That’s when the soil temperature has warmed to 55 degrees Fahrenheit, or 13 Celsius, and the grass emerges from its winter dormancy. At that point, the roots are ready to absorb nutrients. If you wish to feed the lawn again in fall, the right time is right around Columbus Day in October. During the summer, cool season grasses again go dormant from the heat, so roots can’t take up any fertilization – all that you apply will runoff into local waterways.
If you live in the south, you have warm season grasses in your lawn, like zoysia, bermudagrass, St. Augustine grass, and carpetgrass. Warm season grasses slowly green-up in spring, are growing at full throttle in summer, and enter dormancy at the first sign of frost. That means warm season grasses should only be fed in summer, when they’re actively growing, and are able to absorb nitrogen.
Far and away, the best product to fertilize your lawn (besides mulched grass clippings), is organic corn gluten meal. It’s natural (a by-product of corn milling), and slowly releases nitrogen throughout the season. As an added benefit, corn gluten meal acts as a weed suppressant by interfering with the germination of crabgrass seeds and other unwelcome seeds in your lawn.
To avoid bringing in chemical pesticides or fertilizers from intensively managed (GMO) conventional corn fields, ask for organic corn gluten meal at your nearest non-GMO corn supplier. A clover mix of 5-10% will help soil health, increase soil nitrogen levels and allow less space for weeds.
And a few more lawn tips
When you mow, remember that the preferred mowing height for most grasses is 2.5 – 3 inches (6-8 cm). This height allows the grasses to develop deep, strong roots, and the foliage grows tall enough to shade soil in extreme heat and drought.
And just because a lawn fertilizer is from an organic source, that does not mean it’s safe to apply indiscriminately. When it breaks down, nitrogen is nitrogen and phosphorous is phosphorous, regardless of source. Only apply organic fertilizer at the proper time of year and in the proper quantity per square foot.
The bottom line is a gentle feeding of organic corn gluten meal in spring, and mulching blade-shredded grass clippings the rest of the year is usually sufficient to nourish any lawn.
This article was originally published on The Big Blog of Gardening.
* Image of “kids sitting on a lawn” from Shutterstock
