October 22, 2009 at 7:59 a.m.
When confronted with several inches of leaves over the lawn, it is best to rake off the majority of those leaves before mowing and either compost them or use them as mulch material in other parts of the landscape. A thick layer of leaves left on the lawn blocks out sunlight to the grass and may even smother the existing grass beneath that layer resulting, in large areas of thin or dead grass come next spring.
In the Twin Cities, a late season application of nitrogen fertilizer should be put down around Halloween. At this time of year, the nitrogen is taken up into the plant and stored in the crowns, rhizomes, tillers and/or stolons where it can be quickly accessed next spring by the growing grass plant. Follow this application with about ¼ to ½ inch of water to move the nutrients into the soil where they can be taken up by the roots. Never apply fertilizer to frozen ground. You would like about two to three weeks of unfrozen ground following this fertilizer application to allow for root uptake of the nutrients. It is often easy to tell which lawn has had a late season application of nitrogen as they will usually be noticed as the first lawns with healthy growth and a dark green color in early spring.
Any reseeding of the lawn should have been completed by mid-September in the Twin Cities area. It is best to avoid seeding during the early to mid-October period, as the very young seedlings that do emerge often have poor survival over the winter. If you would still like to do some seeding, you can do what's known as dormant seeding. Before the ground is frozen, but while the soil is cold (so as to not encourage seed germination in the fall), incorporate the seed into the soil surface. Incorporating the seed into the soil surface will help protect it through winter. Seed remaining in that 'dormant' condition until next spring, can get a head start on germination and growth for the next growing season. In the Twin Cities area, dormant seeding is usually done in early to mid-November depending on weather conditions.
With a little effort and planning this fall, successfully preparing the lawn will help it survive the upcoming winter months, while also encouraging a healthy start for next spring. It may seem a little backwards, but preparation of a healthy spring lawn begins the previous fall.
(Acknowledgements to Bob Mugaas - University of Minnesota - Yard & Garden News)