This question is difficult, if not impossible, to answer. There are so many factors that influence the sharpness of a reel mower.
Lawn size is the most obvious. A mower that mows a half acre a week will need sharpening more often than a mower used on a small city lawn.
Lawn condition counts, too. Are you mowing tough weeds or hitting sticks, acorns or other lawn debris? Is your lawn rough and uneven? Are you mowing the grass short, so that the blades are “scalping” the lawn – hitting the ground with the mower blades? Scalping will dull the blades very quickly.
Plant fibers become stronger and tougher when they are wet. Moisture is detrimental to the steel blades. So if you cannot avoid mowing wet or damp grass you will need to sharpen more often that the average reel mower owner. You can help your mower to stay sharp longer by cleaning the blades after each use.
Manufacturers often mention sharpening frequency in their sales materials. Manufacturer estimates range from once a year to once every eight years. Each manufacturer may use a different method to arrive at this estimate. Those who have been selling reel mowers for many decades may base their estimates on feedback from their customers, and are probably offering the most accurate estimate. Manufacturers of new models may be guessing, based on the perceived quality of their blades. One manufacturer may estimate conservatively while another is more optimistic than realistic in their estimate. Read the sales materials carefully. Some reel mower manufacturers say their mower will never have to be sharpened. Instead of sharpening you will replace the reel after a few years. Customers rarely replace a reel because it is the most expensive part of the mower. It is not easy to replace. If it is worn out, chances are the rest of the mower is also worn out.
Mowers with a narrow mowing width tend to appeal more to folks mowing a small lawn. Mowers with a wider mowing width are often chosen by people mowing a large lawn. So if the manufacturer is selling a reel mower that is usually used to mow a small lawn, their estimate of time before sharpening will probably not apply to an owner using the same mower to mow a larger lawn.
How particular are you about sharpness? Do you enjoy sharpening things? Some customers tell me that they sharpen their mower once a month. Unless the mower is seeing extremely heavy commercial or institutional use, this is probably not necessary. These customers like to sharpen things and they like a really sharp edge. Some reel mower owners say their decades-old mower has never been sharpened, and it works just fine. So personal preference is a key factor in how often you sharpen your mower.
Your reel mower will become more difficult to push when the blades are dull. If you pick a blade of freshly cut grass it should have a nice clean cut straight across the tip. If that tip looks ragged and uneven, it is time to sharpen.
There are things you can do to protect your blades to maximize the time between sharpening. Spray a bit of WD40, silicone spray or other light lubricant on the reel blades and the cutter bar. The cutter bar is the fixed blade at the bottom of the reel mower, which is sometimes called a bed knife. The lubricant will protect the blades from the moisture that is present even in dry grass. Lubrication will also make mowing easier and quieter.
Check the lawn before you mow. Remove twigs and other debris with a rake or lawn sweeper. Be especially on the alert for small pebbles and wire or other metal objects.
After mowing, clean the clippings off the reel and cutter bar. Manufacturers differ on cleaning instructions. Some say to wash the mower with a hose, some say to use a cloth dampened with water and a mild household detergent. Check your owner’s manual. If you do use water be sure that the mower is thoroughly dried before putting it away.
Reel mowers are gaining in popularity. As a result, it is easier than ever to find a service shop that will sharpen them. Do-it-yourselfers will find that reel mower sharpening kits are easy to use and can save a lot of money. There are kits that are specific to a particular brand of mower and kits that work on most reel mowers, even mowers that are 50 years old or more. Mascot makes sharpening kits for push reel mowers, gang reel mowers and even power reel mowers. You can see them at www.reelmowersetc.com.