When an exhilarating growing season comes to a close, many gardeners breathe a secret sigh of relief at the prospect of a few dormant months. Gardening in Chicago can be a frenzied few months with so many plants to grow and just not enough time to grow them. Even when days shorten and frost is on the pumpkin, there are some important duties left before gardeners can truly call it a night.
By practicing proactive rather than reactive gardening techniques, you can minimize problems next spring through prevention techniques employed this fall.
Regular watering of trees and shrubs is one of the most beneficial of all gardening activities; it shouldn't stop simply because temperatures are cooler. A summer drought stresses many moisture-loving plants, especially all the newly planted trees and shrubs, and homeowners should continue to water the trees deeply, once a week, if rainfall is insufficient. Both broadleaved and needled evergreens lose moisture through their leaves during winter, and they too should be watered all fall until the ground freezes.
Winter winds out of the northwest can desiccate newly planted evergreens facing this exposure. Gardeners might want to construct a burlap windbreak close to, but not touching, the trees to buffer the winds. The burlap will protect plants but still allow in all essential light and moisture. Burlap screens can also reduce the burning effects of salt spray on small evergreens planted next to major thoroughfares.
Established trees and shrubs can be fertilized anytime from late October until the ground freezes. Avoid the routine use of fertilizer, and apply a late-fall treatment only if the plant shows signs of stress, is off-color, or has produced fewer or smaller leaves, flowers or fruit. In these instances, a slow-release form of nitrogen applied at this time might help.
Late fall is an ideal time to fertilize your lawn, especially with an organic source of nitrogen. This helps the lawn retain a more attractive color throughout winter; it promotes sturdy root growth and allows the lawn to green up quickly in spring. Since Midwest soils are naturally high in phosphorus and potassium, avoid fertilizers containing high amounts of these elements, especially on turf areas close to water, where nutrient runoff and the subsequent uncontrolled growth of algae can be real problems.
If a soil test reveals a high pH, incorporate granulated sulfur into the soil surrounding acid-loving plants like rhododendron, azalea, fothergilla, hydrangea, or blueberry. This application can also be repeated in spring.
Spread a fresh, 2- to 3-inch layer of shredded bark over the entire root zone of trees. The mulch insulates roots, protects them from physical damage, and retains moisture. Avoid "volcano mulching" where the mulch gets higher and higher as it nears the trunk. Pull all mulch a few inches away from tree trunks. This helps to keep rodents and insects away from the trunk as well as prevent fungal infections.
New perennial garden beds benefit from a couple of inches of shredded leaves (preferably oak) applied after the ground has frozen. Again, keep the mulch away from the crowns of plants. Many established perennials can remain standing over winter and can be naturally mulched by leaves that blow in.
Roses enter dormancy in fall and should not be fertilized since any new, tender growth they might put forth would not have enough time to harden off before winter cold and winds arrive. Gardeners do need to protect their hybrid roses, but they should wait until there have been two nights of temperatures in the teens or until Thanksgiving, whichever comes first. Prune rose canes to knee height, mound the base of the rosebush with 12 inches of lightweight compost, and cover the rosebush with shredded leaves. Any long canes left sticking out of the leaf pile can conduct cold right down to the crown of the plant or get broken by winter winds.
Homeowners with deer problems might consider "walling off" or "excluding" the plants deer favor with garden netting or snow fencing. Newly planted, smooth-barked trees are prime targets of young bucks trying to remove velvet from their antlers, and these trees should be protected with fencing or wrapping. While repellents, both commercial and homemade, offer temporary relief, barriers are the most effective remedy.
Gardens with a history of mice, meadow vole, or rabbit problems can be protected by eliminating the rodents' winter habitats. Perennials and ornamental grasses should be cut down after a few freezes rather than left standing for winter interest. Eliminate convenient nesting areas for rodents through proper sanitation. If ornamental grasses are planted next to crabapple trees, rodents will happily overwinter in the dried grasses as they gnaw all winter on the bark of the crabapple. Encircle valuable ornamental trees with 12- to 16-inch-high hardware cloth tacked into the soil 3 inches away from the trunks. Chicken-wire fencing will not keep out voles.
Keep snow loads from piling up around tree trunks. Rodent activity takes place both above and below the snow line. Avoid using evergreen boughs as mulch on the perennial garden since they also attract rodents looking for winter homes.
The productivity of gardens depends on what is done before problems develop. Monitor your plants, even in winter. Watch for changes in the same way you watch your plants in the growing season. Act quickly if you notice damage. Prevention and early detection of problems are key to a blooming, healthy garden.