This rationale holds still greater currency in locations that historically suffer rodent damage, which may be expected to be more severe this winter due to the fact that we are at the apex of the cycle of prey populations.  In such cases, I typically recommend a prophylactic application of a slow-release granular repellent containing castor oil, to be spread evenly over the soil after the area has been completely cut back and blown or raked out for the season.  This treatment is also warranted around significant new plantings, particularly of bulbs, since soil cultivated late in the growing season tends to be fairly loose and thus provides easier access to subterranean treats.

Gardens that have been well cleaned up in the autumn tend not to have persistent problems with invertebrate pests and diseases, either, since the act of removing and composting affected herbaceous growth will often interrupt the life cycle of the problem organism, if not cook it out of existence entirely.

Various ornamental grasses are left standing for fall and winter interest.

Of course, we also have significant aesthetic and psychological reasons for so thoroughly cleaning up growing spaces before winter.  To be blunt, if a plant does not exhibit winter interest, it's likely to be something you'd rather not have to look at for three or four months.  Even perennials such as ornamental grasses that are known for winter interest tend to collapse under the pressure of repeated snowfalls by February.  Since I am always of two minds about leaving the grasses anyway, weighing my early-winter visual enjoyment against the labor involved in raking their broken blades up in the spring (when I've plenty else to do), it is not unusual to find me cutting them back during a well-timed midwinter thaw, by which time I find their sloppy presence irksome at best.

Regardless of the necessity of cutting back my myriad varieties of perennials, I always feel unavoidably wistful about the process, even if that feeling is tempered by a sense of relief.  In recent years, I have made a habit of gradually cutting back perennials as they become bedraggled in appearance or succumb to frost.  It's a methodology that I've dubbed "gardening by subtraction", and one that works very well for me because I can make steady gains in the

Miscanthus 'Silberfeder' holds up well to early winter weather.

process without overwhelming myself, either with truckloads of biomass to process all at once, or the shock of a previously burgeoning garden reduced in but a day's time to mere stubs decorating the bare terrestrial plane.  However, this approach does not work for everyone; it really is best suited to those of us who not only have trouble saying goodbye to our perennial friends, but who also tend to garden by means of punctuated equilibrium, ignoring what we need to do until we have the time to do it - and then doing it with gusto.

Regardless of the necessity of cutting back my myriad varieties of perennials, I always feel unavoidably wistful about the process, even if that feeling is tempered by a sense of relief.

Of course, if the end product of the clean-up process leaves one feeling entirely bereft of horticultural stimulation, one ought to seize the opportunity to plan for introducing winter interest into the landscape.  

Finally, one ought not underestimate the great comfort to be found in seeing, or at least knowing that one's garden has been tidily wrapped up for the season, not only cleaned of spent herbaceous growth, annual plants, and debris, but also cleared of certain plants' failings and one's own errors in judgment.  In short, a well-executed garden clean-up offers us the opportunity to approach the spring garden with a clean slate, both on the ground and in our thoughts.

* Tabula rasa, an opportunity to start from the beginning (from the Latin, meaning a clean or blank slate).