Planting fescue in summer conditions is a necessary evil in a lot of areas due to the bell curve of optimal fescue seeding temperatures that can vary from season to season. While there are certain air and soil temperatures that are ideal to encourage turf type tall fescue germination and development, knowing when to seed fescue is not as easy as it sounds and can be very unpredictable. As a result, dormant seed is usually seen when a lawn is overseeded at the beginning or at the end of that window of opportunity.
Typically, turf type tall fescue is most suited for germination and development when air and soil temperatures average between 60F and 75F. With the right temperatures and proper watering, germination can be expected to occur within seven to fourteen days, at which point proper fertilization and continued favorable conditions influence how quickly the baby grass develops and matures.
In a transition zone state like Virginia, typical temperature fluctuations throughout the year are not ideal for any specific type of grass. Winters are too long and cold for warm season lawns like bermuda and zoysia, while summers are too hot and provide too little rain for cool season lawns like fescue and bluegrass. However, most homeowners default to fescue because they prefer a lawn that may struggle for a few months in the summer over one that goes completely dormant and brown for more than half of the year.
Because of these extreme temperature fluctuations between triple digit summer heat waves and deep winter freezes, spring and fall conditions are becoming more and more unpredictable and irregular. Fall is the ideal time to overseed with turf type tall fescue because it gives the baby grass the greatest window of time to develop before it has to withstand summer heats. But how do you know when to seed fescue based on a vague idea of “fall” and an ideal range of temperatures that can’t be accurately predicted, and how do you handle planting fescue in summer conditions?
In the professional turf management network, we typically aim to apply fescue seed between early September and early November. This two month window almost always covers the bell curve of ideal conditions for fall seeding in terms of air and soil temperatures as well as when homeowners are able to tend to the baby grass the best. On the back end of this window, that late October timeframe, the biggest concerns are early season frosts and heavily falling leaves. However, on the front end of this window, the September timeframe, the biggest concern is late season heat waves and resulting dormant seed.
Every year changes significantly in how early or late this cool fall temperatures arrive. We have seen ideal seeding temperatures begin as early as Labor Day on year and then as late as Halloween the next. With this unpredictability experienced in some way by every kind of outdoor service provider, the policy is typically to roll with the punches and provide the best supportive care possible.
As a result, planting fescue in summer conditions is not the end of the world if an aeration and seeding service is provided in September before the weather fully cools off. Rather than the one to two week fescue germination you would typically see in ideal seeding conditions, it may be another week or two before that seed really begins to pop. This delayed is known as dormant seed and occurs when conditions are either too hot and dry or too cold for seed to develop. This is not “dead” seed! This is just seed that is waiting for its time to shine.
If you have had a September aeration and seeding service performed that has resulted in dormant seed due to late season heat waves, patience is the biggest key to success. Your seed just needs an extended period of proper watering and low interference to give it time to do its thing. Dormant seed will be magnified if a homeowner is not watering the seed properly, so your watering habits will be a great impact on the rate of your germination as well.
Planting fescue in summer conditions gives your seed plenty of time to germinate before leaves and frosts become a threat, but it can result in dormant seed for a time if there are prolonged heat waves and little rainfall. As long as your seed is still on the ground, it will come up when the time is right. While seasonal temperatures are unpredictable, what goes up will always come down! Just stay patient and wait for those eventual cooler temperatures.