University of Vermont Extension 
Department of Plant and Soil Science

Fall News Article
Dr. Leonard Perry, Extension Professor
University of Vermont
Just as you make sure your car is ready for winter this time of year, so should you make sure your landscape is ready.
Start by cleaning up the debris in your garden, removing dead foliage as well as the stakes and row markers. Cut back dead growth on your perennials.  These are all measures that not only get your garden and flower beds ready for planting and new growth next spring, but also they prevent overwintering pests and diseases on rotting foliage. Be sure to throw out or burn any diseased foliage. Don't put it into the compost pile.
Have you raked those fallen leaves yet? The grass is still green underneath and can use all the light possible to prepare for winter. Removing leaves also allows water and air to get to the living plants, preventing them from suffocating. For this reason leaves, especially tough ones that pack down and rot slowly, do not make good mulch for perennials and should be raked off perennial beds.
It's too late to divide perennials, but you can cut them back in late fall.  This allows time for birds to get seedheads, for any nutrition to recycle back to the roots from the leaves, and for you to enjoy the fall effect of many perennials.  Of course if they’re diseased or have died back, like many daylilies, you can cut them back sooner.  Cut most perennials back leaving 2 to 6-inches of growth near the base.  Cut ornamental grasses back a bit higher, so not to cut off any growing points for the following year.
You can divide peonies, though, if needed.  If sited properly with plenty of space, peonies may not need dividing for many years or even decades.  But, if they are too large or crowded or you just need to move them, fall is the time.  Cut back leaves (usually not very attractive anyway by fall) to just above the ground.  When plants are dug, you can divide with knife, pruners, or sharp tool.  Make sure each division has at least 3 growing points or buds on the roots called “eyes”—these are quite obvious.  Then, make sure not to plant more than 2 inches below ground, and don’t cover with mulch. 
Wait until late winter or spring to prune woody plants if possible, as doing so now will leave open wounds that won’t heal quickly, allowing diseases the chance to enter.  Of course you can prune any dead, diseased, or broken branches. 
Mulch shrubs, trees, and perennial beds with a loose organic material such as bark mulch. Do it now, and you will have one less job to worry about in the spring. Mulches also help protect roots during winter from cold and fluctuating temperatures.  Don't mulch too thickly--no more than a few inches--around woody trees and shrubs as the mulch makes a nice home for mice, which chew bark. If packed around tree trunks too thick, mulch can smother the tree and cause it to die, so keep it a few inches away from tree trunks.
Prior to mulching you may want to spread some compost around woody plants, so it can work into and enrich the soil over the winter—another less task to do in spring, particularly if you’ll then need to remove the mulch first. Also topdress an inch or two of compost around your perennials, more easily done after they’re cut back.
Another project for this fall, so you won’t need to worry with it during the busy spring planting season, is edging beds.  There are edging tools just for this, manual as well as electric, or you can simply use a spade and hoe to make clean edges and keep the grass away. 
Have you protected your evergreens from drying winter winds? In colder weather the roots of evergreens are frozen and unable to take up water. Winter winds may “desiccate” or dry them out, eventually causing them to die. This is why leaves turn brown-- from lack of water.    Protect your evergreens by putting up a screen on the windy sides, usually the north and west. This can be as simple as erecting three wooden stakes and wrapping burlap around them.  Don't cover the plants directly with plastic. It will heat up like a greenhouse on sunny days and cook your plants. 
For evergreens like the Alberta spruce, place burlap screens on the eastern and southern sides.  Otherwise bright winter sun will rapidly heat the frozen needles, causing them to die and turn brown.
Or, you can spray evergreens with an antidessicant available from your local garden center. This provides a protective layer on the leaves that will wear off by spring, keeping them from losing of “transpiring” so much water over winter.  Some years this may work or not, depending on specific conditions and climate that year.  Research results are mixed on whether or not antidessicants are effective. 
If you have deer nearby, you may want to stock up and spray a repellent on desirable woody plants.  If deer pressure isn’t high, simply hanging bars of smelly soap near plants may work.  But don’t hang them directly on plants, as the dissolving soap on stems will attract mice feeding.  If you have lots of deer or very hungry ones with few other food sources, you may have to resort to electric or high mesh fencing.  If just a plant or two, you can erect a simple triangular mesh fence around each, about 6ft high and foot or so away from the plants.
Did you have “tender” summer bulbs such as gladiolus and dahlias?  If so, dig the dahlia tubers right after tops have been killed with a hard frost.  Gladiolus can be left in the ground until tops yellow and start dying back.  Once the gladiolus corms have been dug and are fully dry, store in a paper bag or similar.  Don’t let dahlia tubers dry more than a day or two, as they’ll begin to shrivel.  Store them in slightly moist (but not too wet, or they’ll rot) materials such as peat moss or wood shavings.  Dry both of these summer bulbs out of direct sun, in a slightly warm, airy location.  Store both in a cool, but non-freezing, space.
As long as the grass is growing, mow.  For me this is usually mid-October.  While you want to mow higher (3-inches) during the growing season, lower this to about 2 inches with your last mowing.  This discourages any mice and rodents from living there, as well as less chance of disease in spring (particularly “snow mold”) from matted-down grass.
If you label your plants, make sure labels are still intact and legible. I like to make an inventory, too, of my planting beds and put on a simple computer spreadsheet during the winter.  This way you can recall what plants you have—particularly important if you have many, and when you come to buying more so you don’t get duplicates. 
If you have lots of different cultivars of a perennial, such as many different daffodils, hostas, or daylilies, you might want to make a map. Invariably labels come out during winter, or even through the season with plant maintenance, and get all mixed up—something a map can help you keep straight.
Don’t forget in fall to walk around and just enjoy your landscape, with notepad in hand.  Make any notes on changes for the coming year, either design or plants or culture, while these thoughts are fresh in mind.

Return to Perry's Perennial Pages, Articles uvmext logo