NOW that autumn is fully underway and the weather has cooled, it is time to take advantage of one of the most important gardening seasons of the year and get some work done in the garden.
If your garden is well established and you are happy with its current presentation state, then perhaps there is little to do beyond regular cleanup chores. However, for the rest of us whose gardens are constantly evolving, growing and not quite what they could be, it's time to take stock of what is and what isn't quite right.
At this time of year the garden's growth has reached is maximum size and accordingly now is the time to do a little walk through and identify those areas that are overcrowded or underplanted. By identifying such problems with the garden's structure it's easy to rectify the situation now, by planting new plants to fill holes or to divide, remove or relocate plants that are crowding their neighbours.
Remember that at this time of year the soil is still warm, there is abundant rainfall to water new plants or transplants and plants naturally make a small growth spurt at this time of year. Planting a new plant or transplanting will yield long-lasting results and fall planting lessens the workload in spring. A friend of mine who recently bought a new house decided that fall planting was not in her best interests because of the concern of winter kill of new plants. It is important to remember that most trees, shrubs and perennials sold commercially in our region are more than hardy enough to survive our mild coastal winters, so there should be little concern for winter kill of new plantings, therefore I do recommend fall planting and transplanting for everyone in our region. The exceptions to the fall planting rule include plants like bananas or fan palms that are tender in our Canadian hardiness zone 8, and several sub-shrubs like Cytisus, Cistus, Caryopteris, perhaps Pervoskia and a few other species that need excellent drainage, sunshine and warm temperatures to establish. But the exceptions are few and far between and not commonly planted. All hardy deciduous, broad-leaved or coniferous trees and shrubs can definitely be transplanted or planted new at this time of year. And being able to accurately gauge the available planting space in the garden provides an opportune moment to accomplish the work.
Fall is not a good time to do several gardening tasks, namely pest and disease control, because plant leaves are undergoing seasonal change and leaf senescence which means their appearance and chemical composition is undergoing change in response to the onset of winter; therefore accurately diagnosing the pest or disease problem is not realistic.
Fall fertilization is another controversial gardening task; some people believe feeding now supports winter hardiness by using fertilizers high in potassium, while other people believe feeding now will only lead to leaching of the fertilizer into groundwater and the ocean due to the high amount of rainfall we receive in our region. I recommend that if you want to fertilize trees, shrubs and perennials at this time of year, only do so if you have a genuine fertility problem and your pH has been accurately tested. I recommend applying organic mulches like manure, compost, soil amender or composted leaf mold to address the diagnosed fertility problem to build soil structure and to improve soil microbial populations; remembering that no chemical fertilizer can accomplish those very important goals. As for colouring hydrangeas in fall by applying aluminum sulphate, I am completely against this unnecessary and potentially soil damaging practice. Excessive aluminum can become dissolved in soil solution and become toxic to plants causing root stunting and preventing root hairs from taking up calcium. Excessive aluminum mobilization in soils also reduces the health of soil micro-organism populations and causes other nutrient-ion antagonisms in the soil blocking nutrients from being taken up at the ionuptake sites on plant root hairs.
It's too early to start preparing your roses for winter, so leave them until November other than a light deadheading to keep the late season blooms coming. You can, however, take the shop vacuum out into the rose beds and vacuum up whiteflies, leafhoppers, spit bugs and aphids from roses, which will help reduce pest populations.
Be careful when using vacuum-based pest control not to suck up beneficial insects like hover flies, ladybugs and lacewings, leave those good bugs alone to settle in for winter so they will cycle their lives in the garden next spring.
With those ideas in mind, there's a lot to do in one of the most colourful season of the year. So don't let a little rain stop you, get out there and dig deep to improve the garden now for next spring's bounty.
Todd Major is a journeyman horticulturist, garden designer, writer, consultant and organic advocate. For advice contact him at stmajor@ shaw.ca