If you are only going to fertilize your lawn once each year, make sure you do it in the fall. We’re not kidding!

This might be surprising to hear for a few reasons. First, conventional wisdom dictates that you do not fertilize in the fall. Trees, shrubs, evergreens, perennials, roses – just about everything else in the garden shouldn’t be fertilized at this time of year. Secondly, what about the spring? Wouldn’t it make sense to fertilize your lawn in the spring to give it a good head-start?

It gets even more complicated. Depending on where you live, the fertilizer needs of your lawn vary. Warm-season grasses in the southern U.S. require fall fertilizer with higher second and third numbers (phosphorus and potassium, respectively). In Canada our lawns are comprised of cool-season grass blends, which instead prefer higher first-number fall fertilizer (nitrogen). There’s also a broad area in the U.S. referred to as a ‘transitional zone’, where these cut-and-dried distinctions get rather murky. Depending on what website you’re using to research your lawn questions you will get varying and possibly unreliable information – don’t use a resource from the state of Georgia to inform your gardening in Ontario!

We’re not done with the confusion yet. The use of high-nitrogen fertilizer in the fall further goes against conventional fertilizer wisdom. Ordinarily, high-nitrogen fertilizers encourage a plant to push out all sorts of tender growth that would be highly susceptible to frost.

So far, it stands to reason that using a high-nitrogen fertilizer in the fall would be complete madness!

But it isn’t, and it all comes down to timing.

Each fall, there comes a period of time when your grass has stopped growing but remains green. During this window of opportunity, you are safe to use a high-nitrogen fertilizer (and we greatly encourage it!).
Because the grass has stopped growing for the season, rather than suddenly pushing out new tender growth it will instead store the provided nitrogen in its roots for the winter.

This is highly beneficial to our lawns. It will improve winter hardiness and will allow our lawns to ‘fly out of the gate’ much faster in the spring than any spring fertilizer would allow. We carry a high-quality granular 18-3-6 fertilizer that is perfectly suited for use as fall lawn food.

Identifying this window of opportunity can be rather tricky, but remember that it is usually quite late in the season. If you’re unsure, err on the side of waiting for a few weeks. If you fertilize too late, no harm is done. If you fertilize too early, your lawn will still be growing, and all of the issues discussed above could become a reality.

This season we continue to have remarkably warm daytime temperatures throughout October, meaning the opportunity to apply fall lawn fertilizer may well be delayed into November. Pay close attention to the weather, but pay even closer attention to your lawn – if you haven’t had a need to mow it in a couple of weeks, then the time for fall lawn fertilizer is drawing near. If you’re worried you’re applying it at the wrong time, give us a call or e-mail us, we’ll be happy to help!

One final note: spring fertilizer is still very important for your lawn. It provides higher quantities of other nutrients (phosphorus and potassium) that are also required for good healthy growth. Once in the spring, and once in the fall is what’s best for your lawn.

Have more questions about your lawn? Check out our lawn care knowledge base for further reading.