In January, DEP’s Sustainable Landscapes Manager traveled to Ireland, and it got us thinking about lawns. Courtyards in 900 year old monastic ruins and fields by 5,000 year old megalithic cemeteries were bright green, yet untouched by fertilizer bottles.
Ireland is on the same latitude as Hudson Bay in Canada. Yet while average January temperatures in Hudson Bay are between -7°F and 10°F, average January temperatures in Ireland are between 39°F and 47°F. The temperature difference is simple: the Gulf Stream brings warm air right across the Irish isles, keeping the temperature moderate year round, and the soil never freezes. It also never gets very hot in Ireland. In fact, the highest temperatures almost never get above 66°F, and there is frequent light rain. Perfect conditions to grow grass.
In January in Ireland, the mowers were running and a smell of fresh grass would permeate the towns. Hillsides were green and sheep were actively grazing. But here in Maryland, the average temperatures in January are between 30°F and 42°F, and our grass is dormant. Forecasts call for snow and freezing temperatures.
The fescues we grow for lawns in Maryland are typically the same species that grow well in Ireland, and are greenest when the weather is similar to Ireland. For our region, we should expect grass to be at its happiest in spring and fall, when temperatures are between 40°F and 70°F, but certainly never in summer when temperatures stay well above 70°F. Despite two and a half more hours of sunlight in Maryland than in Ireland, our fescue grasses go dormant in the deep cold of winter and again in the high heat of summer.
Of course, climate is just one factor is the lushness of Ireland’s grass. Many areas are freely traversed by sheep, who when they graze also leave behind their droppings, which are really just partly digested grass. Cut grass is an excellent fertilizer, but run through the gut of an animal means it’s already partly broken down for quick update by soil microorganisms. And where the sheep graze, they also aerate the soil, which is great for microorganisms and soil moisture.
Fescue grasses are happiest when the weather is cool, so let them go dormant and brown to rest in the heat of summer to grow deep roots. Be sure your soil is aerated, which helps it retain moisture and improve habitat for microorganisms. And keep your lawn off a chemical diet, so it can do it what does best in a healthy soil–grow green.