Barring any last exceptions, perhaps on the Cape or the islands, the vast majority of turf areas in the state have had a final mowing by this point in time. The grass plants are not asleep just yet, however, despite a few frigid dips in temperature. A quick survey of current soil temps indicates that soils remain unfrozen, while the region is yet to have a lasting snowfall. This implies that we are still at the tail-end of the winter hardening period for our cool-season grasses.
At this late stage in the game we frequently receive questions about dormant seeding. The current summary position is as follows: dormant seeding is never as effective as an ideal late summer seeding, of course. When late summer seeding is not an option available research suggests that dormant seeding may or may not be as effective as an early spring seeding, depending on a host of factors. Some potential advantages of dormant seeding include less initial irrigation and weed control attention, and the approach can be especially suited to moist sites that may be difficult to prepare and plant during other times of the year.
Extenuating circumstances aside, we normally advise that dormant seeding be done only with the goal of encouraging greater density or filling in bare areas, as opposed to establishment of new stands of turf. With dormant seeding there are very few variables that you can actually control, and there are many unknowns over which there is no control that can easily sink a project. The primary risk is a warm spell during the winter or early spring that initiates germination of tender seedlings which are subsequently killed if bitter cold returns. For this reason, dormant seeding often works better for slower-establishing species such as Kentucky bluegrass, and less well for faster species like perennial ryegrass. Dry air and winds during winters with little snow cover can also cause seeds to desiccate, greatly reducing germination percentage.
Here are some related tips:
- The target time for dormant seeding is when it is too cold for seed to germinate, but the ground is not yet frozen. Shoot for air temps consistently below 50º and soil temps in the low 40s or below. It is better to err on the side of too late than too early. Soils above freezing are not an absolute requirement, but unfrozen soils can be prepared better to promote good seed-to-soil contact.
- As noted above, faster germinating species such as perennial ryegrass may be more prone to early germination. Slower germinating species such as Kentucky bluegrass often fare better.
- Use higher seeding rates (perhaps 50% more or greater), as significantly less seed will ultimately germinate compared to a conventional seeding.
- If possible, slice seeding will offer a little more protection to the seed from the elements and hungry birds. If not, broadcast seed into a prepared seed bed.
- Some claims indicate that seeding prior to predicted snowfall will give the seed a good start and help settle it into the soil.
- If using a mulch, avoid dark colored mulches that can provide a warming effect and encourage premature germination.
In short, if the long-term weather outlook seems favorable and the time and cost involved isn't an issue, then dormant seeding is certainly worth a shot. If the stars align it is possible to come out way ahead of the game in the spring. If you are counting on it to work, then there should also be a contingency plan for project failure.